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To repair a pipeline system, an automatic welding process is used to carry out the sleeve welding. In this study, the repair performance of the sleeve was studied, and the research results will help improve the repair quality of pipeline systems in the future. The results show that the tensile strength of the fillet weld was lower than the minimum nominal tensile strength of X65 steel. There were small cracks at the root of the fillet weld. The fracture surfaces of the side bend test of the butt weld and the notching hammer break test of the fillet weld indicated defects to different degrees. The tensile tests of butt welds indicated breaks in the base metal, and the average tensile strength was 587 MPa. The ductile-brittle transition temperature of the butt weld and the fusion line ware both lower than −60°C , and the average crack tip opening displacement (CTOD) values of −10°C fracture toughness tests of the butt weld and heat affected zone were 0.181 and 0.510 mm, respectively. [ABSTRACT FROM AUTHOR]

This study experimentally investigated the effect of temperature conditions on the welding quality of thermoplastic sheets by non-destructive and destructive testing methods. Ultrasonic inspection method was employed for evaluating the fusion welds. Since the thermoplastic materials lead to significant ultrasonic signal attenuation, optimizing the setting condition for the ultrasonic testing was carried out in advance. Then, ultrasonic experiments were performed to evaluate welding qualities with respect to welding temperature conditions. In the partially incomplete welding specimen, two distinct signals were observed, reflected from the intermediate and back wall. The quality factor was defined using the ratio between intermediate and backwall reflection signals to evaluate the welding characteristics according to temperature. Based on this factor, ultrasonic images were produced using a C-scan method for welded thermoplastic specimens to visualize the welding quality. Lap-shear tests were conducted to verify the ultrasonic testing results for the welded specimens. As the welding temperature increased, there was a maximum decrease of 28 % in the percentage of incomplete welds in the C-scan results, and the lap-shear test showed an increase in shear strength. Validation through temperature-dependent shear strength confirmed the effectiveness of C-scan images using ultrasonics. [ABSTRACT FROM AUTHOR]

A P22 (2.25Cr-1Mo) steel pipe is machined into two separate plates and then joined across with a V-groove by manual arc welding. The welded plate is further cut into three pieces and each piece is post-weld heat-treated (PWHT) at temperatures of 680 °C, 700 °C, and 720 °C for different holding times of 0.5, 1, and 2 h at each temperature. The welding area is typically categorized into three regions: base metal (BM), heat-affected zone (HAZ), and weld fusion (WF). As-weld and PWHT samples are characterized by destructive techniques of microscopy and hardness measurement and non-destructive evaluation (NDE) of magnetic behaviors. The WF region shows a bainitic lath structure, correlated to its high hardness and coercivity and low Barkhausen voltage. In contrast, the change in microstructure towards HAZ and BM decreases dislocation density, displaying a continuous decrease of hardness and coercivity and increasing Barkhausen voltage. This is endorsed by a decrease in magnetic and mechanical softness profiles, sequentially proceeding from WF towards HAZ and BM, while this softening behavior changes with PWHT temperatures and holding time. After PWHT at 720 °C for 2-h holding time, the magnetic softening along the welding region indicates an actual trend compared to mechanical softening. The electromagnetic parameters are considerable to identify the correct PWHT conditions necessary to maintain the accurate stress-relieving operation of weldments. [ABSTRACT FROM AUTHOR]

In the present work, the Q345B low-alloy steel with different contents and ER309L stainless steel were melted together to obtain new alloys. The aim was to design the composition of weld metal (Q345B low-alloy steel as the base material and ER309L welding wire as the filler material) and improve the corrosion resistance of the weld metal. During the welding process, the composition of the weld metal was controlled to match the new alloys by changing the welding heat input. A relationship curve between fusion ration and welding heat input was obtained. The research focused on analyzing the effect of mixed-smelting ratio between Q345B and ER309L and welding heat input on the microscopic structure and corrosion performance of the prepared samples. The results show that the melted alloys containing 20% to 30% Q345B consist of a ferrite (δ) phase and austenite (A) phase, the samples containing 45% to 50% Q345B consist of a martensite (M) phase and austenite (A) phase, and the sample containing 40% Q345B consists of a martensite (M) phase, ferrite (δ) phase, and austenite (A) phase. As the mixed-smelting ratio of Q345B/ER309L increased, the corrosion resistance of samples decreased gradually. For the weld metal, the fusion ration between Q345B base material and ER309L welding wire increases with the welding heat input. When the heat input changed from 0.645 kJ/mm to 2.860 kJ/mm, the composition of the weld metal was consistent with the melted alloys containing 20–45% Q345B. The microstructure and corrosion resistance of the weld metal could be designed by the melting means, which has important guiding significance for engineering applications. [ABSTRACT FROM AUTHOR]

In the present study, considering the features and advantages of solid-state welding methods as compared with fusion welding methods such as arc welding, laser welding induction welding, and solid-state welding, they are used to connect CK45 steel to AISIS 304L steel to achieve the desired mechanical and metallurgical properties through experimental and practical tests, by trial and error, suitable parameters of distance, depth, and advance are obtained for welding, and finally a healthy and desirable weld is obtained. The purpose of the present study is to evaluate the weldability of CK45 steel to AISIS 304L steel by friction stir welding method. The distance, advance, and penetration depth parameters were experimentally determined as 950 rpm, 24 mm/min, and 0.35 mm, respectively, to obtain a healthy weld in terms of appearance. Then, through mechanical and metallurgical tests, the effect of the input parameters on the friction stir welding process was determined. The mechanical and metallurgical properties were also evaluated. The results show that the structure of the onion rings in the welding area is caused by the friction stir welding process, which is caused by the massive plastic deformation and the heat generated during the process. The scanning electron microscope image of the welded section of the steel sample shows the formation of a pearlite structure. Considering the severe plastic deformation and dynamic recrystallization in the friction stir welding process, the results obtained from the welding of dissimilar CK5 and AISI304 L show better mechanical properties and acceptable strength. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Metal Working (1674-165X) is the property of Metal Working Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to its moderate mechanical properties, low neutron absorption, excellent processability, superior irradiation, and corrosion resistance, as well as good compatibility with nuclear fuel, zirconium (Zr) and its alloys have been extensively employed as fuel cladding tubes and structural materials in the nuclear industry. This review examines research progress on the joining of Zr alloy with dissimilar materials over the past 20 years, encompassing friction welding, fusion welding, diffusion bonding, brazing and resistance welding. It also compares and analyzes the impact of these welding methods and processes on the mechanical properties and microstructure of Zr alloy joints. Finally, the paper addresses the future direction of Zr alloy joining. Aimed at discussing and analyzing recent progress in the joining of Zr and dissimilar materials, this review lays the groundwork for subsequent research related to Zr joining in the nuclear industry. [ABSTRACT FROM AUTHOR]

AbstractA non-traditional friction stir welding (FSW) is used to joint the materials that are challenging to join together by utilizing the fusion welding processes. This study investigated the influence of the welding speed ratio (υ) to rotating speed (ꞷ) on the weld quality and found the relationship between mechanical qualities and welding peak temperature. With increase in (ꞷ/υ), there was a corresponding rise in peak temperature, leading to the expansion of both the nugget zone (NZ) and the softened region within the joint. As (ꞷ/υ) increased because of the increased heat, as a result in the joint hardness decreased. The joint ultimate tensile strength (UTS) increased with increasing (ꞷ/υ), then decreased, with the maximum value reaching 84.75% of the base material at a (ꞷ/υ) of 9.6. As a result of the low (ꞷ/υ), a flexural crack formed. In comparison to the base material, the thermos mechanically affected zone (TMAZ) and the nugget zone (NZ) showed greater impact strength. The impact strengths first increased and subsequently dropped with an increase in (ꞷ/υ). The tensile specimens’ fracture surfaces showed dimples, signifying a ductile mode of fracture. [ABSTRACT FROM AUTHOR]

In this study, 316L austenitic stainless-steel (ASS) plates fabricated using an additive manufacturing (AM) process were joined using tungsten inert gas (TIG) and laser welding techniques. The 316L ASS plates were manufactured using a laser powder bed fusion (LPBF) technique, with building orientations (BOs) of 0° and 90°, designated as BO-0 and BO-90, respectively. The study examined the relationship between indentation resistance and microstructure evolution within the fusion zone (FZ) of the welded joints considering the effects of different BOs. Microstructural analysis of the weldments was conducted using optical and laser confocal scanning microscopes, while hardness measurements were obtained using a micro-indentation hardness (HIT) technique via the Berkovich approach. The welded joints produced with the TIG technique exhibited FZs with a greater width than those created by laser welding. The microstructure of the FZs in TIG-welded joints was characterized by dendritic austenite and 1–4 wt.% δ-ferrite phases, while the corresponding microstructure in laser-welded joints consisted of a single austenite phase with cellular structures. Additionally, the grain size values of FZs produced using the laser welding technique were lower than those produced using the TIG technique. Therefore, TIG-welded joints showcased hardness values lower than those welded by laser welding. Furthermore, welded joints with the BO-90 orientation displayed the greatest cooling rates following welding processing, leading to FZs with hardness values greater than BO-0. For instance, the FZs of TIG-welded joints with BO-0 and BO-90 had HIT values of 1.75 ± 0.22 and 2.1 ± 0.09 GPa, whereas the corresponding FZs produced by laser welding had values of 1.9 ± 0.16 and 2.35 ± 0.11 GPa, respectively. The results have practical implications for the design and production of high-performance welded components, providing insights that can be applied to improve the efficiency and quality of additive manufacturing and welding processes. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a solid-state joining process of similar or dissimilar metals including thermoplastics. This technique came into practice when difficult-to-weld materials like Aluminum, Magnesium, Titanium, and other metal alloys along with polymers were not able to be joined by fusion welding. These light metals and polymers have enormous applications in areas of construction, synthesis of composites, and pipeline distribution, etc., as they possess high strength for their application at extreme conditions. Their replacement after the generation of crack or leakage led to high-cost investment. Metals and composites containing two or more similar or dissimilar elements can be sound welded by FSW considering the process parameters like tool rotation speed, welding speed, feed rate, welding tool material, and its dimensions used, etc. Although this method of joining was familiar for metals and metals alloys more specifically to aluminum, magnesium, and their alloys, its reach has now extended up to the joining of metal in form of composites in processed area and welding/processing of polymers too. The need for polymer composites has increased because of their enhancement in mechanical properties over metallic composites. Many researchers have progressively used FSW for welding/joining polymers and their composites. This review reflects the understanding of developments in FSW for the fabrication and joining of similar and dissimilar metals, metal-alloys, and polymers summarizing in terms of the effect of process parameters on properties, microstructure, strength, and efficiency. [ABSTRACT FROM AUTHOR]

Carbon and low-alloy steel plates clad with stainless steel or other metals are a good choice to meet the demand for cost-effective materials to be used in many corrosive environments. Numerous technical solutions are developed for the production of clad steel plates, as well as for their joining by fusion welding. For thick plates, a careful strategy is required in carrying out the multiple passes and in choosing the most suitable filler metals, having to take into account the composition of the base metal and the cladding layer. The specificity of the different processes and materials involved requires an adequate approach in the study of the metallurgical characteristics of clad steel, thus arousing the interest of researchers. Focusing mainly on ferritic steel plates clad with austenitic steel, this article aims to review the scientific literature of recent years which deals with both the production and the fusion welding processes. The metallurgical issues concerning the interfaces and the effects of microstructural characteristics on mechanical behaviour and corrosion resistance will be addressed; in particular, the effects on the fusion and thermally affected zones that form during the fusion welding and weld overlay processes will be analysed and discussed. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue on advanced and unconventional manufacturing processes. It includes research articles on topics such as friction welding, laser direct joining, tool wear, and surface quality evolution. The articles cover a range of processes and techniques aimed at improving the efficiency, sustainability, and quality of manufacturing. The authors come from various research groups around the world, highlighting the global expertise in the field. The special issue provides valuable insights and knowledge for researchers and practitioners in the manufacturing sector. [Extracted from the article]

In recent years, hybrid materials combining aluminum alloys and steels have gained popularity across various industries due to their lightweight design and superior mechanical properties. However, joining these dissimilar metals is challenging because conventional fusion welding often fails due to significant metallurgical differences, leading to poor weld quality and increased defect susceptibility. Friction stir welding (FSW) has emerged as a promising technique to address these issues. This article reviews recent advancements in FSW of aluminum alloy and steel components, focusing on aerospace, marine, and automotive applications. It examines the impact of FSW parameters on intermetallic compound development and dissimilar weld joint characteristics. Topics include interlayer applications, modified FSW procedures, and numerical simulations predicting flow behavior, temperature profiles, and residual stresses. The study aims to be a valuable resource for professionals and researchers seeking to improve the joining of high-performance materials in key industries. [ABSTRACT FROM AUTHOR]

The AA7075 high-strength aluminum alloy exhibits a pronounced tendency for hot cracking during fusion welding, which hampers its widespread utilization in lightweight design concepts. This study aims to investigate the effectiveness of friction stir processing (FSP) as a pre-weld treatment to eliminate the occurrence of hot cracking during fusion welding of the AA7075 aluminum alloy. Our findings demonstrate that the FSP pre-weld treatment successfully suppresses liquation cracking in the AA7075 alloy, even when utilizing ER1050 filler metal for welding, which poses a considerable risk of liquation cracking. The FSP treatment induces a transformative effect on the microstructure of the hot-rolled material, leading to the conversion of the typical large elongated pancake-shaped grains into refined recrystallized grains. Electron backscatter diffraction (EBSD) analysis confirms the introduction of finer grains, characterized by an increased grain boundary area, and higher volume fraction of low angle grain boundaries within the partially melted zone (PMZ) of the friction stir processed base metal. This leads to a reduction in the thickness of the liquid film and consequently diminishes the susceptibility to liquation cracking. These findings prove that arc welding with FSP pre-weld treatment is an enabling welding strategy for producing high-performance AA7075 joints. [ABSTRACT FROM AUTHOR]

Welding defects have a significant influence on welding quality and structural strength, and the rapid and accurate detection of welding defects is required. In order to achieve this goal, it is imperative to create corresponding high-quality datasets. However, capturing image information through a single sensor presents certain limitations. In this study, a magneto-optical imaging device and an infrared thermal imaging device were combined to collect images of resistance spot welding samples. The imaging principles of magneto-optical imaging device and the infrared thermal imaging device are discussed, and the possible factors affecting the imaging modes are analyzed. By synthesizing the 3D gray image, the gray histogram, and inherent image features, the imaging rules of magneto-optical image and the infrared image of resistance spot welding samples have been summarized. Under the guidance of these two image types and imaging modes, image enhancement technology has been utilized to optimize the quality of sample images. The Peak Signal to Noise Ratio (PSNR), Structural Similarity Index (SSIM), and Universal Image Quality Index (UIQI) indicators were used to evaluate the optimization quality of the enhanced images. Compared with Histogram Equalization (HE), the Gamma transform, Brightness Preserving Bi-Histogram Equalization (BPBHE), and the Digital Detail Enhancement (DDE) method, the scores of the enhanced infrared images showed improvement across all indicators. The magneto-optical image yielded the best results in the PSNR index, while the other two indices showed only moderate performance. The image dataset, enhanced with appropriate image enhancement techniques, can be utilized for further research into magneto-optical and infrared image information fusion and welding defect identification. [ABSTRACT FROM AUTHOR]

Owing to their unique high-temperature mechanical properties and outstanding high-temperature oxidation resistance, superalloys have become key materials in aviation, aerospace, petrochemical, metallurgy, electric power, automotive, and other industrial fields. Due to the structural complexity and high manufacturing cost of the hot sections of aeroengines, vessel engines, and gas turbines, the development and practicality of superalloy welding technology are critical to satisfying the design and maintenance requirements of hot sections. In this work, the research progress of superalloy fusion welding is described. Its advantages and application scope, such as arc welding, electron beam welding, and laser welding, are elaborated. Common types of welding cracks are introduced, and the mechanisms and influencing factors of solidification cracks, liquation cracks, strain-age cracks, and ductility-dip cracks are summarized. The primary techniques to enhance the weldability of fusion welding are also examined in terms of heat input, material composition, microstructure, and welding residual stress. The requirements for the temperature-bearing level of superalloys in industrial development are constantly increasing; thus, the types of superalloys are also being iteratively updated. They have evolved from deformed superalloys to ordinary cast polycrystalline superalloys to novel superalloy materials such as directional solidification and single-crystal superalloys. Thus, continuously conducting welding research on emerging superalloys, traditional nonweldable superalloys, and dissimilar materials that are extremely incompatible with metallurgy is necessary. Because the composition and microstructure of the base material have an important bearing on weldability, it is necessary to strengthen the composition design of emerging superalloys and conventional nonweldable superalloys in future works. Moreover, it is critical to pay attention to the improvement of welding process technology and pre- and post-weld treatment methods. In particular, research on detection and elimination measures of welding residual stress should be strengthened, which is one of the most effective approaches for lowering the weld crack-sensitivity of superalloys. This is of great importance for synergistically enhancing the welding performance of superalloys. Moreover, monitoring and simulation techniques for the welding process can be used to perform in-depth research on scientific issues such as molten pool flow and welding heat and mass transfer during the fusion welding process. This is of great scientific value for promoting the development of fusion welding technology. Based on the foundation of enhancing welding processes, future work on automation and intelligence of welding processes should also gradually deepen, which is one of the important directions to improve welding stability and reliability and promote the widespread application of superalloy fusion welding.

High strength low alloy steels which are having excellent corrosion-resistant properties are called corten steels. In the present investigation, 3 mm thick ASTM A242 Corten steel sheets were welded together using the cold metal transfer (CMT) method based on two welding controllable parameters like welding current and welding speed. The controllable input parameters like welding current and welding speed have been altered to produce joints that have no flaws and a complete depth of weld penetration. The evaluation of the microstructure and weld geometry was performed for the cold metal transfer welded ASTM A242 sheets using ER70S6 filler wire. The experimental design of welding parameters was developed using an orthogonal array of full factorial design. The dominance of acicular ferrite microstructure is visible in the fusion zone. Results from Energy Dispersive x-Ray Analysis (EDAX) show that manganese content is higher and nickel concentration is lower in the weld fusion region. The fusion zone of the CMT welded specimen has the greatest hardness, which was measured at 270.2 HV. Due to the formation of acicular and bainite microstructure in the welding seam, the tensile properties at room temperature (RT) were found to be 589.79 and 405.63 MPa, accordingly. Bend tests additionally confirmed the satisfactory ductility of the welded joint. [ABSTRACT FROM AUTHOR]

The stress crack resistance (SCR) of high-density polyethylene (HDPE) geomembrane extrusion welds is examined for a 1.5 mm HDPE geomembrane and three different welding parameter combinations (denoted as "Cool", "Good", and "Overheated"). Results are reported for unnotched welds, unnotched sheet, and notched sheet. The average SCR for a Good extrusion weld is 23% of that of the unnotched sheet SCR. Little variation is found between the three welding parameter combinations for low geometry irregularity SCR weld specimens. There is no statistically significant difference between a good-quality fusion and extrusion weld. However, operator-dependent weld induced geometric irregularity (WIGI) greatly affects the SCR of extrusion welds. Extrusion welds with high WIGI have an average unnotched SCR of only 9% of the unnotched sheet. Extrusion welds with an overground surface can have an unnotched SCR as little as 1% of the best extrusion weld. Deleterious weld bead geometries are identified to provide a framework with which engineers can identify "high-risk" extrusion welds with respect to stress cracking. • Paper highlights: • First examination of the effects of weld-induced geometric irregularity (WIGI) in extrusion welds on unnotched stress crack resistance. • Highlights the impact of poor quality control for extrusion welds (e.g., overgrinding, high WIGI, and scratches) on the likelihood of stress cracking in the field. • Demonstrates that a good extrusion weld (i.e., low WIGI, good grinding, and appropriate welding temperature) has a comparable unnotched stress crack resistance to that of a good fusion weld. • Demonstrates that the operator-dependent nature of extrusion welds substantially increases the variability in the stress crack resistance of extrusion welds compared to fusion welds. • Highlights the importance of doubling the standard oxidative induction time (Std-OIT) of welding rod to reach a post-welded bead's Std-OIT similar to the sheet's Std-OIT (i.e., it shows a 50% decrease in Std-OIT of the extruded bead compared to the initial rod entering the extruder). [ABSTRACT FROM AUTHOR]

High-strength dissimilar aluminum alloys are difficult to connect by fusion welding, while they can be successfully joined by friction stir welding (FSW). However, the asymmetrical deformation and heat input that occur during FSW result in the formation of a heterogeneous microstructure in their welded zone. In this work, the grain structure and texture evolution in the bottom zones of dissimilar FSW AA2024-T351 and AA7075-T651 joints at different welding speeds (feeding speeds) were quantitatively investigated. The results indicated that dynamic recrystallization occurs in the bottom zones of dissimilar FSW joints, and equiaxed grains with low grain sizes are formed at the welding speed of 60–240 mm/min. A high fraction of the recrystallized grains were generated in the bottom zones of the joints at a low welding speed, while a high fraction of the substructured grains are produced at a high welding speed. Different types of shear textures are produced in the bottom zones of the joints; the number fraction of shear texture types depends on different welding speeds. This study helps to understand the mechanism of microstructure homogenization in dissimilar FSW joints and provides a basis for further improving the microstructure of the welded zone for engineering applications. [ABSTRACT FROM AUTHOR]

The results of experimental studies in the manufacture of components of the supporting structure of the first wall panel, carried out as part of the manufacture of a model of the International Thermonuclear Experimental Reactor (ITER) using laser welding technology, are presented. The influence of laser welding modes on the quality of formation, microstructure characteristics, and mechanical properties of a welded joint made of 10 mm thick 316L steel was studied. A coaxial nozzle was designed and manufactured to protect the weld pool with a curved trajectory. The mechanical properties of the welded joint are 98–100% that of the base metal, and the microhardness of the welded joint and base metal is in the range of 180–230 HV. It was established that the lower part of the weld metal on the fusion line has transcrystalline grains and differs in δ-ferrite content; due to a high welding speed, the ratio of the depth to the width of the welding seam is 14 times. The width of the rectilinear part of the seam is 15–20% larger than its curved part. [ABSTRACT FROM AUTHOR]

AA6061-T6 and AA7075-T6 aluminium metals are broadly used in structural and aerospace sectors due to their exceptional features, but fusion welding causes thermal cracks, high residual stresses, and coarse grains, weakening joints. To solve these issues, pulsed tungsten inert gas (P-TIG) welding was used to improve the grain structure and mechanical features of the dissimilar joints. In this investigation, four peak currents (110, 120, 165, and 175 A) and four pulse frequencies (4, 8, 12, and 16 Hz) with constant base current, pulse on time, and argon flow rate were utilized, and the microstructural features were investigated and correlated with the joint's mechanical properties. The welded sample P4 developed a void-free joint with the maximum tensile strength (~ 201 MPa), elongation (~ 17%), microhardness (~ 101 HV), and compressive residual stresses (~ 76 MPa) compared to other welded samples. Microstructural evolutions revealed that, as the pulse current and frequencies increased, the grain refinement and grain boundary transformations across the FZ became more pronounced, and the segregation of alloying elements was lower. Specifically, for welded samples P4, the average grain size decreased to 21 μm, and the grain boundary transformations reached 73.32%. Moreover, the orientation density value of the welded joints was much lower than that of the base metals, suggesting that the texture was greatly reduced after welding, which further reduced the anisotropy of the mechanical properties. [ABSTRACT FROM AUTHOR]

The laser direct fusion welding of SiO 2 ceramics was a global challenge in the manufacture of radome. The paper explored the laser direct fusion welding of SiO 2 ceramics, investigated the influence of filling powder addition and welding material composition on the formation of weld. The findings revealed that the addition of welding material effectively addressed the issue of weld formation in laser direct fusion welding SiO 2 ceramic. However, the abundance of internal bubbles within the weld emerged as a significant impediment to further enhancing weld strength. The addition of SiO 2 /Al 2 O 3 mixed powder not only significantly reduced the quantity and size of internal bubbles within the weld but also generated the strengthening phase Al 2 SiO 5 , leading to a substantial increase in weld shear strength, reaching a maximum of 106 % of the base material. The research results provided a new solution for direct melting welding of ceramics. [ABSTRACT FROM AUTHOR]

Weight reduction strategies are essential for the transportation sector to reduce greenhouse gas emissions or extend the range of electric vehicles. In the field of lightweight assembly strategies, multi-material design offers great potential. Joining materials typically used in the automotive sector, such as aluminum and steel, brings challenges as conventional processes such as fusion welding are unsuitable. Therefore, new technologies can extend the design options. In previous studies, a mechanical interlocking between cold-rolled surface structures with undercuts on a steel sheet and die-cast aluminum was presented. This method has now been extended to double-sided structures for more complex applications with a joint on both sheet surfaces. Numerical simulations and validation experiments were performed to investigate the manufacturing of the double-sided structures. Furthermore, the influence of the alignment of the upper and lower structures in relation to each other on the resulting structural geometry and the rolling forces were analyzed. More advantageous geometric parameters, e.g., 24% larger undercuts, and approx. 24.1% lower forming forces at 20% height reduction were observed for a shifted alignment. However, significantly higher wear of the structured rollers occurred in the corresponding experiments. [ABSTRACT FROM AUTHOR]

High‐density polyethylene (HDPE) is one of the most used thermoplastic materials for piping applications, due to its significant advantages. The butt‐fusion process is the most used joining processes for HDPE welding. During the process, the behavior of the material changes. This behavioral change depends on the applied welding process and on the used parameters. Thermal analysis can be used as a tool to reveal and evaluate the modifications of the physical and mechanical properties. In this study, an experimental program was applied to HDPE to assess the effects of different parameters on the welding process including heating temperature, heating duration and the applied strength. Tests are performed according to a full factorial design of experiment (DOE). Mathematical models derived from experimental data are used to establish relationships between the input parameters, such as force and heating duration and the corresponding outputs such as temperature distribution during the different welding phases and the thickness of the molten polymer. The empirical models can be used to implement a control strategy for the temperature and hence quantify the thickness of the molten zone to improve the quality of the weld joint by selecting the appropriate welding conditions for the molten zone. Highlights: High‐density polyethylene piping butt‐fusion joint examination using Infrared imaging.Spatial–temporal distribution of temperature for different phases of the welding process.Mathematical Regression techniques are performed.Thickness of molten polymer is assessed.Results are useful for saving material and improvement of the process. [ABSTRACT FROM AUTHOR]

The issue of obtaining high-quality welds in plates made of AL9 alloy using powder through selective laser fusion is addressed. Welded butt joints in plates made of AK9 alloy having a thickness of 3.0 mm are made using welding (automatic argon arc and electron beam welding) and friction stir welding. After welding, the base metal of AK9 alloy plates and the welded joints are studied using X-ray transmission, computer tomography, metallographic analysis, and mechanical tests to get information on static tension and static three-point bending. X-ray inspection of welded joints made by automatic argon arc and electron beam welding reveals multiple porosity inside the welds. Spherical micropores formed in the parent metal during selective laser fusion act as pore nuclei inside in the weld metal. These micropores have a diameter of 150–200 µm. During fusion welding, micropores grow in diameter to 420–1070 µm in the welding bath in the case of argon arc welding and to 215–420 µm in electron beam welding. Metallographic analysis of fusion welding cross sections of welded joints reveals a characteristic pore distribution in the weld metal. In the case of argon arc welding, the largest pores are located near the front surface of the weld. The pores having a diameter of 80–220 µm form chains along the entire thickness of the welded plates in the fusion zone at the border of the weld and the base metal. It is in this zone that welded joints break under static tension. The welding factor of the AK9 alloy joints obtained by fusion welding is as follows: for automatic argon arc welding, it is 0.46; for electron beam welding, it is 0.66. It is established that the porosity issue can be eliminated in welded joints through solid-phase welding to make butt welds (through friction stir welding). The welding factor of the butt welds made in AK9 alloy plates performed by friction stir welding stays at a level of 0.81–0.86 of the ultimate strength of the base metal. The break of welded joints occurs across the stir zone. The weld zone formed during friction stir welding undergoes dynamic recrystallization resulting in forming a fine-grained equiaxial structure with an average grain size of 4.5–6.2 µm. There is almost no pores in this structure. The base metal is represented by a cell structure featuring pores up to 168 µm in size. [ABSTRACT FROM AUTHOR]

The joining of aluminum alloys using fusion welding often leads to issues such as hot tears, porosity, distortion, and solidifying cracks. To address these challenges, solid-state welding processes like Friction Stir Welding (FSW) are preferable. This study investigates the FSW of dissimilar aluminum alloys AA 5083 and AA 6061-T6, employing Acoustic Emission (AE) techniques for real-time monitoring. FSW was conducted under conditions with no defects, pinhole defects, and piping defects. The resulting joints were evaluated for their mechanical properties and metallurgical characteristics. Microstructural analysis was performed using an optical microscope, revealing that the defect-free condition achieved the highest tensile strength of 256 MPa and superior hardness of 93 HV at the stir zone. Tensile failure commonly manifested within the heat-affected zone (HAZ) of AA 6061-T6, primarily due to grain enlargement and the impact of Mg2Si precipitates. Examination of the fractured regions via scanning electron microscopy revealed ductile-mode fractures featuring elongated dimples and microvoids. AE parameters such as hits, amplitude RMS, and energy were analyzed, demonstrating that defect-free welds had consistent AE signal patterns, while significant variations were observed in pinhole and piping defect conditions due to larger defect areas. The findings suggest that AE monitoring is effective in detecting and analyzing welding defects, providing valuable insights into the FSW process for dissimilar aluminum alloys. [ABSTRACT FROM AUTHOR]

In this study, fusion welding of a Ni-Mo base superalloy (Hastelloy B-2) is examined to study and disclose the chemistry–processing–microstructure links. Moreover, welding metallurgy, alloying element redistribution, and alloy solidification are studied in depth under pulsating current waveform-induced heat generation and successive solidification. Characterizing effects of current intensity and frequency on microstructure evolution and alloying element redistribution at different weld zones is the main goal of the current work. The pulsed current gas tungsten arc welding (PC-GTAW or PCGTAW) process and ERNiCrMo-2 filler metal are used for the preparation of welded samples. Microstructure, chemistry, and precipitate formation in the samples are analyzed by optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that a decrease in the maximum current intensity leads to a severe decrease in the dendrite size of the weld metal, while the grain size of the heat-affected zone does not experience a significant increase. Moreover, a significant decrease in the number of molybdenum carbides at interdendritic regions of the weld metal is observed. Meanwhile, the weld pool size and thus weld metal dimensions increase by an increase in the pulse frequency. It also extends the overlap of the successive pulses, which results in more heat input into the molten pool at a shorter time and thus increasing weld size. The microstructural studies indicate an increase in the dendrite size and grain size of the HAZ with pulse frequency increasing. Meanwhile, microstructure evolution, alloying element redistribution, and alloy solidification are studied in depth to understand the welding metallurgy of the alloy. [ABSTRACT FROM AUTHOR]

The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043—AlSi5 was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511. [ABSTRACT FROM AUTHOR]

The residual stress creates deleterious effects on joint properties of dissimilar welding due to differential thermophysical properties and mechanical constraints of dissimilar thickness. Accounting of solid-state phase transformation (SSPT) through the understanding of solidification behavior enhances the prediction accuracy of residual stress. The characterization of microstructural features improves the fundamental understanding of the residual stress evaluation. An attempt is made to comprehend the dependence of heat input on phase transformation and its effect on the generation of compressive residual stress in dissimilar welding. Three distinct heat inputs of 52, 63, and 77 J/mm are considered in micro-plasma arc welding (µ-PAW) of SS316L and SS310 with thicknesses of 800 µm and 600 µm, respectively. The measurement of residual stress is performed using the X-ray diffraction (XRD) method. The variation of δferrite from 11.2 to 7.9% is analogous to the variation of average δferrite lath size from 412 to 1040 nm, where inter-dendritic spacing varies from ~ 10 µm to ~ 20 µm. The solidification mode is identified as ferritic-austenitic (FA), which results in the formation of skeletal and lathy δferrite structures. Electron Backscatter Diffraction (EBSD) results show an increase in heat input leads to an increase in low-angle grain boundaries that results in a rise in the residual stress value. The phase fraction and residual stresses are computed employing a finite element (FE) based thermal-metallurgical-mechanical (TMM) model including the effect of SSPT. The reasonable agreement between the computed and experimental measurements with a maximum error of ~ 8.5% in weld size, ~ 7.5% in peak temperature, ~ 16% in retained δferrite, ~ 17% in residual stress, and ~ 5% in distortion demonstrates the reliability of the developed model. A lower level of heat input (52 J/mm) allows the formation of a high amount of δferrite, which generates comparatively more compressive stress as a disparity in thermal expansion coefficient α Ni ∼ 1.6 α Cr aids in the reduction of residual stress. [ABSTRACT FROM AUTHOR]

Due to their outstanding corrosion resistance, mechanical characteristics and low specific density, AA5083 and AA6061-T6 Al alloys are used in the aerospace, automotive and marine sectors. Joining such dissimilar Al alloys using conventional fusion welding techniques is very challenging. In contrast, laser beam welding (LBW) is a non-conventional welding technique that is promising to weld dissimilar materials. The viability of welding dissimilar AA5083 and AA6061-T6 joints using fibre laser welding are examined herein. The effect of laser power and welding speed on the morphological, microstructural, microhardness and tensile strength of the welded joints was assessed and revealed that increasing welding power resulted in deeper keyhole penetration. Microporosities were formed due to Mg evaporation and shrinkages; however, the existence of these porosities did not show significant effect on the tensile strength. The microhardness values indicate that the welds were harder than the AA6061 and AA5083 base metals. This is explained by the existence of Mg2Si phase in the AA5083-AA6061 dissimilar junction in addition to the grain size circumstances. The fracture examination showed brittle fracture pattern that is regarded to the formation of brittle intermetallic compound (IMC) phases of Mg2Si, in addition to the inter-dendritic brittle phases of other sites as they were frequently inter-granular. [ABSTRACT FROM AUTHOR]

CaF2 has been a very common constituent in the fluxes used for welding of low‐carbon steel plates, owing to its strong ability to lower the liquidus temperature as well as viscosity of the molten flux. But the adverse impact of fluoride evaporation from molten slag on the health of operating personnel and the environment has prompted a worldwide effort to replace CaF2 with more benign constituents. Three compositions with varying MnO concentration in the CaO–MnO–SiO2–Al2O3 system, identified in the current work, have shown promise in terms of ability to control oxygen transfer and modify inclusion generation in the molten metal during the welding of low carbon low alloy steels. However, the melting behavior of a flux needs to be established before recommending its use for welding. Three compositions, with varying MnO concentration, are chosen in the current work. Aided by experimental measurements using high‐temperature microscopy, DTA and simulations using the commercially available thermodynamic package FactSage (version 8.3), this work aims to understand the melting characteristics of the developed fluxes. These characteristics seem to be comparable with a commercial CaF2‐containing welding flux, used as a reference for comparison. In addition, simulations using FactSage suggest that transfer of dissolved O, Si and Mn to the weld metal, while using these fluxes, would be benefitial to performance of the welded joint. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) of galvanized steel offers unique advantages as it can avoid the extensive metallurgical problems associated with fusion welding. However, conventional FSW still leads to a higher temperature in the stir zone, which deteriorates the microstructure. To obtain a satisfactory weld, the welded joints of galvanized steel were created by FSW with different cooling rates employing a W–Re rotary tool with a large-diameter needle. The correlation between the microstructure evolution and mechanical behavior of joints at different cooling rates was systematically studied. The results demonstrate that the rapid cooling rate favors the refinement of ferrite and diffuse distribution of Fe3C. In addition, weakening of the texture and dispersion of dislocations were also observed after fast cooling FSW. It can be concluded that the microstructural evolution mechanism of the stirring zone (SZ) is continuous dynamic recrystallization at a slow cooling rate, while the microstructure has discontinuous dynamic recrystallization as the primary evolution mechanism at a fast cooling rate. Based on these advantages, the tensile specimens with fast cooling FSW obtained a synergistic improvement in strength-ductility, even surpassing the base material. This work provides new ideas for welding galvanized steel. [ABSTRACT FROM AUTHOR]

Based upon calculated data compositions of experimental aluminum alloys, which are characterized by the lowest tendency towards hot brittleness during casting, are selected. Sheets 2.5 mm thick are obtained from ingots of experimental alloys by hot rolling. It is shown that weldability of the Al–1Ca–5.5Zn–1.5Mg–0.5Mn alloy is at the level of that for serial alloy 1915. Analysis of the obtained data shows that cracking characteristics of the Al–2Ca–2.5Mg–0.4Mn alloy (alloy 2) (specimen cracking coefficient and critical deformation rate) are at a level corresponding to AMg3 alloy. The alloys studied with appropriate surface preparation are not prone to pore formation during fusion welding. Mechanical properties of joints of the alloys studied during argon-arc and plasma welding are determined. [ABSTRACT FROM AUTHOR]

Narrow gap welding of 316L stainless steel thick plate was carried out using the cold metal transition pulsed wire-arc swing method. The effects of heat input, arc swing, and shielding mode on weld shaping and lack of fusion were investigated, and microstructure and tensile properties of welded joints were analyzed and characterized. The results indicate that arc swing amplitude was the primary factor affecting sidewall fusion. The tendency of undercut and incomplete fusion at the weld toe increased with the increase of wire feeding speed. Narrow gap weld with built-in shielding was easy to produce pores. The microstructure of welded joints was mostly represented by twin crystals in HAZ and columnar dendrites in the weld. Solidification sub-boundaries were produced between dendritic crystal clusters in the middle of the weld under high heat input, resulting in severe regional segregation and crystalline cracks that extended along subgrain boundaries. The microhardness of the weld and HAZ was greater than that of the base material. The tensile strength of welded joints was comparable to that of base material with good mechanical properties. [ABSTRACT FROM AUTHOR]

Explosive welding allows joining metals and alloys in almost any combinations unlike various types of fusion welding. It provides the ability of manufacturing products with a combination of service properties of applied materials with a high level of strength, tightness, fatigue strength, etc. In addition to bimetals produced in fairly large volumes for chemical and oil equipment, explosive welding is used to manufacture products with special characteristics for different industries. Producing coaxial joints (welding is performed along generatrices of axisymmetric coaxial tubes) can be attributed to a special class of tasks, since they are more economical than alternative methods of their production. In some cases, a permanent joint can be created by explosion compression without welding of elements to be joined. This work presents a number of technological processes for manufacturing coaxial products developed at the PWI, which use both welding and explosive compression. The presented developments testify that a wide range of practical tasks can be solved with the help of explosion. [ABSTRACT FROM AUTHOR]

Dissimilar welds between ferritic and austenitic steels represent a good solution for exploiting the best performance of stainless steels at high and low temperatures and in aggressive environments, while minimizing costs. Therefore, they are widely used in nuclear and petrochemical plants; however, due to the different properties of the steels involved, the welding process can be challenging. Fusion welding can be specifically applied to connect low-carbon or low-alloy steels with high-alloy steels, which have similar melting points. The welding of thick plates can be performed with an electric arc in multiple passes or in a single pass by means of laser beam equipment. Since the microstructure and, consequently, the mechanical properties of the weld are closely related to the composition, the choice of the filler metal and processing parameters, which in turn affect the dilution rate, plays a fundamental role. Numerous technical solutions have been proposed for welding dissimilar steels and much research has developed on welding metallurgy; therefore, this article is aimed at a review of the most recent scientific literature on issues relating to the fusion welding of ferritic/austenitic steels. Two specific sections are dedicated, respectively, to electric arc and laser beam welding; finally, metallurgical issues, related to dilution and thermal field are debated in the discussion section. [ABSTRACT FROM AUTHOR]

Joining high strength 2xxx series aluminum is known to be complex and difficult; these alloys are traditionally considered non-weldable for fusion welding. This paper describes details on welding AA2029-T8 for skin-stiffened structures using refill friction stir spot welding (RFSSW). RFSSW is a solid-state process invented in the early 2000s that produces spot welds that are strong, lightweight, flush, and hermetic. Cycle times between 1 and 3 s are discussed, and process forces within a range of 8 to 14 kN are demonstrated. Furthermore, lap-shear quasi-static tensile strengths are shown to be between 10 kN and 12 kN in 9 mm diameter spots. A comparison of the performance of RFSSW welds made with various tool materials—which include H13 tool steel, tungsten carbide, and MP159—is detailed. Comparisons of parameters, weld consolidation, and heat-affected zones are presented with discussion related to heat generation specific to each tool material. [ABSTRACT FROM AUTHOR]

In the manufacturing sector, welding has long been a popular method of combining materials. Hence, there has been a lot of research in this area, leading to evolution of conventional welding techniques. These developments widened its feasibility enabling the process to be functional in diverse crucial applications. A detailed review of various research efforts carried out in the field of welding provides an ideal repository which can effectively help identify various research gaps. This paper intends to throw light on the following aspects of welding: a detailed description of different fabrication methods involved in fusion and solid-state welding processes, weld performance evaluation on the basis of mechanical properties, microstructure, corrosion, wear and fatigue behaviour followed by a brief summary of various applications. The mechanical properties and microstructures of various commercially viable alloys like steel, DSS, Ti-6Al-4 V, Al- Mg alloy, AZ31, AA6061, Al-Zn-Mg-Cu and Ni-base super alloys have been discussed in detail. Various mechanisms which influenced the changes in microstructure and resulting mechanical behaviours have been discussed. The inferences obtained as a result of microstructural, mechanical, corrosion and wear property analysis have been correlated to understand major areas of application. The extensive data compiled in this study aims to give readers valuable insights and inferences on a vast topic, which promises great scope for development in the future. [ABSTRACT FROM AUTHOR]

In this study, the welding performance of three filler wires, ER4043, ER5356, and the newly developed FMg0.6, were systematically investigated in the gas metal arc welding of high-strength AA6011-T6 plates. An extensive analysis of the microstructural evolution, mechanical properties, fatigue resistance, and corrosion behavior of different weldments was conducted. The ER4043 and FMg0.6 joints exhibited finer grain sizes in the fusion zone (FZ) than the ER5356 joint. The as-welded ER5356 and FMg0.6 joints exhibited higher hardness and tensile strength values than the ER4043 joint. The FMg0.6 joint demonstrated the highest mechanical strength among all of the joints with superior fatigue resistance under both the as-welded and post-weld heat treatment (PWHT) conditions. In the as-welded state, the ER5356 joint exhibited the lowest corrosion resistance, attributed to the precipitation of β-Al2Mg3 at the grain boundaries. The FMg0.6 joint, characterized by a high-volume fraction of eutectic Mg2Si in the as-welded state, exhibited a higher corrosion rate than that of the ER4043 joint. However, the PWHT effectively improved the corrosion resistance of the FMg0.6 joint. Given its excellent tensile properties, superior fatigue properties, and satisfactory corrosion resistance, particularly with PWHT, the newly developed FMg0.6 filler has emerged as a promising candidate for welding high-strength 6xxx alloys. [ABSTRACT FROM AUTHOR]

Fe–Mn alloys have been identified as suitable candidates for structural applications that require damping. Damping is the ability of a material to convert mechanical vibrations into other forms of energy (usually heat), which is then dissipated in the material. Fe–Mn alloys do this by the oscillatory movement of various boundaries in their microstructure. Fabricating large structural damping components often requires fusion welding, so it is important that these alloys are weldable. The welding metallurgy and weldability of three high manganese steels were investigated using Varestraint testing, 3D heat flow and solidification modeling, electron probe microanalysis (EPMA), and scanning electron microscopy (SEM). The high manganese steels studied were found to have poor resistance to solidification cracking compared to existing weldable commercial alloys. Through heat flow and solidification modeling, it was established that the ranking of the alloys in the Varestraint test correlated to the size of the crack-susceptible solid + liquid region formed during welding. This was further investigated by tracking solute segregation behavior and its effects on secondary phase formation. Aggressive solute segregation and the concomitant formation of deleterious secondary phases degraded weldability in these alloys. Although it is useful for damping purposes, Si was found to be particularly detrimental to weldability in Fe–Mn systems. [ABSTRACT FROM AUTHOR]

Flow-accelerated corrosion (FAC) preferentially attacks the downstream heat-affected zone of the root-pass weld in steam pipe systems. A detailed characterization identifies the fusion boundary as the initiation location for the attack. Alloying elements are found depleted along the weld fusion boundary, and multiple welding thermal cycles and repetitive austenite-to-ferrite phase transformations result in an increased proportion of grains with Goss {110}<001> texture along the fusion boundary. The synergistic effects of chemical segregation and the Schmid factor may contribute to the preferential initiation of FAC cracks along the root weld fusion boundary, making it the weakest link for FAC attack in steam pipe girth welds. [ABSTRACT FROM AUTHOR]

There are a lot of problems with the conventional fusion welding process, so ultrasonic welding has been used for about 20 years and has helped a lot of manufacturing industries, including aviation, medicine, and microelectronics. Ultrasonic welding takes less than one second, making it suitable for mass production. Poor weld quality and joint strength are common issues that industries encounter as a result of this process. Actually, the success and quality of the welding are determined by its control parameters. This research examines the impacts of weld time, vibrational amplitude, and weld pressure on the welding of 0.6 mm thick sheets of two different metals, specifically copper and aluminum (AA2024). Responses, including tensile shear stress, weld area, and T-peel stress, are acquired through experiments that follow a full factorial design including four replicas. The highest recorded tensile shear stress was 4.34 MPa, the maximum weld area measured was 63.6 mm2, and the peak T-peel stress reached 1.22 MPa. A second-order non-linear regression model was constructed using all of these data points, which related the responses to the predictors. Due to the importance of quality in the production sector, the process parameters were determined by the combination of genetic algorithm (GA) and fuzzy logic (FL) approaches. The impact of the weld zone temperature on various quality characteristics has been investigated through experiments. It has been noted from the confirmatory test that FL produces superior output outcomes compared to the genetic algorithm, with FL achieving a fuzzy multi-performance index of 0.94 compared to 0.61 for GA. By conducting microstructural analysis, weld quality levels, including "under-weld," "good weld," and "over-weld," were established. [ABSTRACT FROM AUTHOR]

The influence of the conditions of nonconsumable (TIG) and consumable (MIG) electrode arc welding of high-strength aluminium alloy of 2219-Т31 grade (USA) 5 mm thick was studied. Effective welding modes were selected by the main characteristics: absence of coarse defects, weld form factor, standard mechanical properties, and features of fracture surface relief. The strength level of welded joints after welding is 25‒30 % lower compared to base metal (σt = 366‒370 MPa). The impact toughness values of the welds after TIG welding vary from 16.4 to 20.3 J/cm², according to the rolling direction. Bend angle is almost 3 times lower than the base metal value (180 and 177°). Fracture of joints with technological reinforcement and of the weld root occurs along the boundary of weld fusion with the base metal, and at a distance from the surface — along the weld axis. The relief retains a predominantly cellular structure. Analysis results were used to establish the technological conditions of achieving an optimal quality of welds and the type of shielding gas for welding. [ABSTRACT FROM AUTHOR]

The need for combining dissimilar materials is steadily increasing in the manufacturing industry, and the resulting products are expected to always have high performance. While there are various methods available for joining such material pairs, one of the commonly preferred techniques is fusion welding. In this study, three different steel materials (Protection 600T, DP450, and S275JR) were joined using gas metal arc welding (GMAW) in different combinations (similar/dissimilar). The microstructure and mechanical properties of the joints were evaluated. Tensile test, Vickers microhardness (HV 0.1), bending, Charpy V-notch impact testing, and microstructure examinations were conducted to analyze the weld and heat-affected zone. The tensile strengths of the base metal materials Protection 600T, DP450, and S275JR were found to be 1524.73 ± 18.7, 500.8 ± 10.4, and 508.5 ± 9.5 MPa, respectively. In welded samples of similar materials, the highest efficiency was found to be 103.05% for DP450/DP450, while in dissimilar welded joints, it was 105.5% for the DP450/S275JR pair. Hardness values for the base materials Protection 600T, DP450, and S275JR were measured as 526.5 ± 10.5, 153.8 ± 1.8, and 162.5 ± 5.2, respectively. In all welded samples, there was an increase in hardness in the weld zone (due to the welding wire) and the heat-affected zone (due to grain size refinement). While the impact energy values of similar material pairs were close to the base material impact energy values, the impact energy values of dissimilar material pairs varied according to the base materials. In addition, in joints made with similar materials, the bending force was close to the base materials, while a decrease in bending force was observed in joints formed with dissimilar materials. As a result, the welding of DP450 and S275JR materials was carried out efficiently. Protection 600T was welded with other materials, but its welding strength was limited to the strength of the material with low mechanical properties. [ABSTRACT FROM AUTHOR]

Unlike different type of fusion welding, explosion welding allows joining metals and alloys in almost any combinations, which provides the possibility of manufacturing products with a combination of service properties of the used materials at a high level of strength, tightness, fatigue strength, etc. Except of bimetals produced in fairly large volumes for chemical and oil equipment, explosion welding is used to manufacture products with special characteristics for different industries. It is possible to attribute the production of coaxial joints of different metals (welding occurs along generatrices of axisymmetric co-axial pipes), which are more complex and interesting from a scientific point of view, and more economical in practice than alternative methods of their production, as a special class of tasks. In some cases, dissimilar joint can be created by explosion crimping without welding the elements to be joined. This work presents a number of technological processes for manufacture of coaxial products developed at the PWI, using both explosion welding and crimping. The presented developments testify that a wide range of practical tasks can be solved with the help of explosion. 18 Ref., 11 Fig. [ABSTRACT FROM AUTHOR]