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In this research, fillet welding was conducted on 8-mm thick Miilux OY Protection 600 (MIL-A-46100) armor steel using AWS A5.9 GeKa ER307 austenitic filler wire. The welding process involved robotic MIG/MAG with five different heat inputs ranging from 0.3 to 1.2 kJ/mm. The study focused on examining the influence of heat input on the microstructure, elemental changes, microhardness, and dimensions of the weld metal and the heat-affected zone (HAZ). These investigations were conducted to determine the welding parameters that they satisfy the quality requirements of the MIL-STD-1185 standard for this steel grade and weld consumable. Through analysis of macrostructure, microstructure, and microhardness, it was observed that increasing the heat input led to a decrease in hardness for both the weld metal and the HAZ, while expanding the HAZ width. The weld metal exhibited a homogenous hardness distribution at lower and higher heat inputs, but hardness increased from the root to the face for both heat inputs of 0.5 and 0.7 kJ/mm welds. Notably, a significant decrease in hardness occurred in the transition of partial transformation region (intercritical HAZ) and tempering region (subcritical HAZ) for heat inputs above 0.7 kJ/mm, indicating softening. Moreover, the width of the subcritical heat-affected zone substantially increased. Evaluation of the distance required to reach base metal hardness from the welding toe revealed that a heat input of 1.2 kJ/mm exceeded the maximum requirement of 15.9 mm according to the MIL-STD-1185 standard. However, the requirements of the military standard were satisfied for other heat input values. These findings were associated with microstructural changes in grain size, martensite, bainite, martensite/austenite morphology and their fractions, as well as delta ferrite morphology. The results successfully demonstrated that robotic GMAW welding can be applied using lower strength (undermatched) filler metal to satisfy the requirements of the respective standard of MIL-STD-1185. [ABSTRACT FROM AUTHOR]

In order to obtain results from simulations that are close to reality, it is necessary to correctly set the parameters of the welding process. One of them is the efficiency of the welding process. Currently, new modifications of MIG/MAG methods are being created, which are characterized by lower heat introduced into the material (smaller efficiency coefficient). The efficiency coefficient determined by the European standard EN 1011–1 is no longer accurate enough for simulations. Therefore, it is necessary to accurately determine the efficiency coefficient of the method even for the mentioned modified welding processes. An experiment of calorimetric measurement of the efficiency of the CMT process (cold metal transfer—modification of the MIG/MAG method) was proposed. The specific heat capacity of the base material was accurately measured. Furthermore, a calorimetric measurement of the efficiency of the welding process was carried out on a flat sample (bead-on-plate method) and on a sample with a V-groove to simulate the treatment of welding surfaces. Accurate method efficiency values were determined for different welding current settings and different V-groove depths. The geometric characteristics of the fusion faces in butt welds have a greater influence on the efficiency coefficient than the size of the welding current. [ABSTRACT FROM AUTHOR]

This study investigates the effect of welding parameters on the microstructural evolution and mechanical properties, such as tensile strength and hardness, in mild steel plates welded using gas metal arc welding (GMAW). The welding parameters examined include welding current, arc voltage, and gas flow rate, with ER K-71 T filler wire as the consumable material. Results indicate that a higher welding current and reduced gas flow rate result in a maximum tensile strength of approximately 533 MPa. However, discrepancies were noted in the microhardness data across different zones, with the heat-affected zone (HAZ) exhibiting a hardness of 115.8 HV, while the weld zone and base metal showed values of 76.7 HV and 112.9 HV, respectively. Microstructural analysis revealed the presence of bainite and ferrite with a tempered martensitic structure in the welded area, demonstrating that the combination of welding parameters plays a critical role in controlling phase transformations and mechanical behavior. It is essential to reconcile the observed hardness values with the conclusions drawn to ensure accurate interpretation of the data. Highlights: The study investigates how different welding process parameters, including current, voltage, and gas flow, affect the internal structure and mechanical characteristics of weld metal. It was found that the highest tensile strength is achieved with a combination of high welding current and low gas flow rate. The welded joint shows greater hardness in the heat-affected zone compared to the original metal, with the fusion zone being less hard. Analysis of the weld area reveals the presence of bainite, ferrite, and tempered martensite, which are responsible for the mechanical properties observed. [ABSTRACT FROM AUTHOR]

In this study, the relationships between the values of the parameters included in heat input (welding current, arc voltage and welding speed) and their effects on the size of the cross-sectional areas of welds in joints made of ferritic–austenitic stainless steel using the GMAW method were determined. An attempt was also made to determine to what extent it will be possible to predict the properties of fabricated welded joints using the functional relationship describing the effect of the value of heat input on the size of the cross-sectional area of welds. The analysis of the developed mathematical models shows their suitability for explaining (and predicting) the sizes of the cross-sectional areas of welded joints depending on the values of the input parameters of the welding process. Determining the regression function and making a three-dimensional plot of it (response surface) can provide a starting point for optimizing the parameters of the welding process. The results have practical relevance, supporting weld quality control and process design in industrial conditions, especially in applications requiring high strength and corrosion resistance, in industries such as construction and offshore. [ABSTRACT FROM AUTHOR]

Narrow-gap arc welding is an efficient method that significantly enhances industrial production efficiency and reduces costs. This study investigates the application of low-alloy steel wire EG70-G in narrow-gap gas metal arc welding (GMAW) on thick plates. Experimental observations were made to examine the arc behavior, droplet transition behavior, and weld formation characteristics of double-wire welding under various process parameters. Additionally, the temperature field of the welding process was simulated using finite element software (ABAQUS 2020). Finally, the microstructure and microhardness of the fusion zone in a double-wire, single-pass filled joint under the different welding speeds were compared and analyzed. The results demonstrate that the use of double-wire GMAW in narrow-gap welding yielded positive outcomes. Optimal settings for wire feeding speed, welding speed, and double-wire lateral spacing significantly enhanced welding quality, effectively preventing side wall non-fusion and poor weld profiles in the welded joints. The microstructure of the fusion zone produced at a higher welding speed (11 mm/s) was finer, resulting in increased microhardness compared to welds obtained at a lower speed (8 mm/s). This is attributed to the shorter duration of the liquid molten pool and the faster cooling rate associated with higher welding speed. This research provides a reference for the practical application of double-wire narrow-gap gas metal arc welding technology. [ABSTRACT FROM AUTHOR]

The microstructure, impact properties, and crystallographic characteristics of the coarse-grained heat-affected zone (CGHAZ) in a new 1000 MPa grade ultra-high strength steel with varying heat inputs through were investigated by single-pass welding thermal simulations. As the heat input increased from 10 to 50 kJ/cm, the main microstructural constituents of the CGHAZ transitioned from lath martensite (LM) to lath bainite (LB) and subsequently to a combination of LB and granular bainite (GB). The CGHAZ exhibited a brittle fracture behaviour, and the impact energy initially increased and then declined with higher heat input. The lowest microhardness and the highest impact toughness were observed at a heat input of 20 kJ/cm. According to the results of EBSD, the proportions of high angle grain boundaries (HAGBs) and lower kernel average misorientation (KAM) values were the highest at a heat input of 20 kJ/cm. These factors collectively contributed to the enhancement of impact toughness. [ABSTRACT FROM AUTHOR]

The fabrication of multi-layer alloys by additive friction stir deposition (AFSD) results in a complicated microstructure and mechanical property evolution due to the repeated thermal inputs impacting the existing deposited layers. This work systematically studied the microstructure and mechanical properties of several areas (last layers, intermediate layers, and first layers) of a 16-layer 2195 alloy component fabricated by AFSD to ascertain the effect of repeated thermal cycling. The periodic heat input resulted in the minimal quantities of T1-phase only appearing in the last layers of the sample, while the θ′-phase developed a complex precipitate with the δ′ and β′ phases. The mechanical properties of the 2195 sample exhibit a gradient development related to the microstructure, with a decrease in strength and hardness from top to bottom. The samples located in the last layers show the highest microhardness of 117.0 Hv, yield strength of 296.6 MPa, ultimate tensile strength of 440.6 MPa, and elongation of 27.1%, respectively. [ABSTRACT FROM AUTHOR]

Welding is key sector in the manufacturing industry, and plays a critical role in making possible joints of different materials is achievable. Nevertheless, certain attributes of the welding process must be addressed, to ensure joints durable and reliable are produced. Hence, the objective of this paper is to evaluate the influence of heat input on the mechanical properties of a Tungsten Inert Gas (TIG) welded joint. Data obtained reveals that the most stable bead width is recorded at a low heat input. Therefore, maintaining and controlling the heat input is capable of guaranteeing the value of the bead width. Also the relatiobship between critical weld properties, which is the bead width and the tensile strength, as obtained from variation arising from the heat input, shows that the most maximum bead width is recorded at a very high tensile strength. An indication that the heat input has a corresponding effect on the bead width and tensile strength of the weld. [ABSTRACT FROM AUTHOR]

In automotive industries, pulsed laser welding has been gaining importance for joining of thin sheet materials for various reasons, e.g., no use of any filler material, precise control over heat input, penetration depth, molten pool shape and short welding cycle. However, improper choice of heat input can lead to the development of weld defects. Hence, the current study is aimed to comprehend the influence of heat input (32.5, 56.25, 72.22 and 92.22 J/mm) on the weld thermal cycle, microstructural evolution and tensile deformation behavior of Nd:YAG pulsed laser-welded dual-phase (DP 780) steel joints in butt configuration. The effect of pulsation on the weld thermal cycles and the corresponding microstructural changes has been studied. It is estimated that the temperatures in the fusion zone (FZ) ranges from 1759 to 1891 K for 32.5 J/mm heat input and 1964 to 2116 K for 72.22 J/mm heat input welds. Depending on heat input microstructures in the FZ containing martensite, bainite and ferrite are changed due to change in the peak temperatures and the cooling rates. Due to softening of FZ and heat-affected zone by tempering of martensite and because of ferrite grain coarsening the yield strength, tensile strength and uniform elongation decreased with an increase of heat input. All welded joints failed in the softened heat-affected zone, and it was found that the amount and distribution of tempered martensite altered the void nucleation mechanism during the tensile deformation. [ABSTRACT FROM AUTHOR]

High-quality weld metals are a prerequisite for ensuring the integrity of dissimilar steel welded joints. This research investigates the influence of heat input on the inclusion characteristics, variant selection, crystallographic texture, and resultant impact toughness of dissimilar weld metals used in joining heavy-plate medium Mn steel (MMS) and V-microalloyed steel (VMS). Results revealed that inclusion density decreased but its size increased as heat input increased from 10 to 15 and 20 kJ/cm, which alters in the nucleation mechanism of acicular ferrite (AF) from intragranular nucleation to sympathetic nucleation. The percentage of AF initially rose from 81.3 % to 83.2 %, and then declined to 79.1 %. Variant selection also transitioned from random to specific due to the variation in transition temperature and nucleation mechanism. Meanwhile, the fraction of unfavourable crystallographic texture increased from 1.5 % to 22.9 % and 26.1 %. Impact toughness was higher (128 J) at 10 kJ/cm compared to 15 kJ/cm (108 J) and 20 kJ/cm (110 J) owing to its smaller inclusion size and a lower percentage of unfavourable crystallographic texture. These findings offered theoretical guidance for selecting welding parameters in industrial applications for dissimilar welded joints of MMS and VMS.

Abstract Repair welding technology is widely used in the manufacturing and maintenance of rail transit equipment to repair welding defects. However, repair welding induces modifications in joint performance, and it is necessary to study the microstructure evolution behavior to reveal the reasons. In this study, the effects of multiple repair welding on the microstructure, mechanical, and fatigue properties of 06Cr19Ni10 stainless steel samples were studied. The surface texture and fracture morphology analyses of the samples were conducted by optical microscopy (OM), scanning electron microscopy (SEM), and its equipped backscattered electron diffraction (EBSD) technique. The mechanical and fatigue properties of the samples with different repair welding times were further obtained by hardness, tensile, and fatigue tests. The results show an increase in the grain size and the substructure content in the heat-affected zone (HAZ), and the austenite orientation is changed, attributable to multiple repair welding. Multiple heat inputs result in a significant increase in hardness from 165 HV to 185 HV, a noticeable decrease in tensile strength and elongation, and an upward trend in yield strength. Under the constant stress level, the heat input of multiple repair welding causes a decrease in the fatigue life and significantly reduces toughness in the instantaneous fracture zone of the secondary repair sample.

The Ce‐containing novel cryogenic high‐Mn austenitic steel weld metals under different heat inputs are prepared by submerged‐arc welding to provide a satisfactory welding parameter scheme and further optimize its cryogenic impact toughness. The effect of heat input on microstructure, inclusion, and cryogenic impact toughness of weld metals are investigated via optical, scanning electron microscopy, electron backscatter diffraction, electronic probe microanalyzer, and cryogenic impact test. The results show that the dendrite arm spacing, segregation ratio of Mn, Si, and C elements and average effective grain size of the weld metals gradually increase, and the proportion of high‐angle grain boundaries decrease with the heat input increase from 11.91 to 20.24 kJ cm−1. The type of inclusions of weld metal with different heat inputs are all Ce2O3 and Ce2O2S. The number density of inclusions decreases monotonically from 5976 to 4912 mm−2, while the average size increases from 0.32 to 0.45 μm with the heat input increased. The increase in heat inputs consistently decreases the mean cryogenic impact toughness of weld metals from 123 to 102 J. The higher proportion of high‐angle grain boundaries and finer inclusions at lower heat input play the critical role in improving the cryogenic impact toughness. [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 Journal of Central South University is the property of Springer Nature 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.)

Repair welding technology is widely used in the manufacturing and maintenance of rail transit equipment to repair welding defects. However, repair welding induces modifications in joint performance, and it is necessary to study the microstructure evolution behavior to reveal the reasons. In this study, the effects of multiple repair welding on the microstructure, mechanical, and fatigue properties of 06Cr19Ni10 stainless steel samples were studied. The surface texture and fracture morphology analyses of the samples were conducted by optical microscopy (OM), scanning electron microscopy (SEM), and its equipped backscattered electron diffraction (EBSD) technique. The mechanical and fatigue properties of the samples with different repair welding times were further obtained by hardness, tensile, and fatigue tests. The results show an increase in the grain size and the substructure content in the heat-affected zone (HAZ), and the austenite orientation is changed, attributable to multiple repair welding. Multiple heat inputs result in a significant increase in hardness from 165 HV to 185 HV, a noticeable decrease in tensile strength and elongation, and an upward trend in yield strength. Under the constant stress level, the heat input of multiple repair welding causes a decrease in the fatigue life and significantly reduces toughness in the instantaneous fracture zone of the secondary repair sample. [ABSTRACT FROM AUTHOR]

The paper studies the heat treatment effect on the structure and mechanical properties of gas metal arc-welded heat-resistant steel walls obtained by coldArc welding. The specimens are tempered at 600 and 900 °C. It is found that 900 °C tempering leads to a complete recrystallization of the structure, higher ductility, and lower strength. High-temperature tests are carried out at 550 °C. [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]

Analysis of publications has shown that the use of the exothermic addition with a combined oxidizer (xCuO + (x-1)Fe2O3-Al) as components of filler materials will reduce energy consumption and increase the efficiency of the welding/hardfacing process. However, in the literature, there are no studies of exothermic addition with combined oxidizers, which allow to vary the chemical composition of the deposited metal within a wide range. In this paper, the use of exothermic addition with combined oxidizer (xCuO + (x-1)Fe2O3-Al) was considered. To study the characteristics, standard methods were used to determine the arc stability, melting characteristics, weld bead morphology, melting-energy characteristics, and efficiency parameters, and mechanical properties were made. The structural characteristics were analyzed by optical microscope (OM), X-ray diffractometer (XRD). Microhardness values of the hardfaced samples were obtained using a Vickers hardness tester. The greater stability of arc voltage was shown by the processes performed with flux-cored wires in which oxidizing agents of exothermic addition Al-CuO-Fe2O3 in the core filler were taken with an equal content of oxidizing agents or with a slight excess of oxidizing agent CuO/(CuO + Fe2O3) = 0.5–0.6, whereas the greater stability of the welding current was shown by the processes carried out with the use of flux-cored wire with the exothermic addition with an equal or greater proportion of Fe2O3 oxidizer in the combined oxidizer CuO/(CuO + Fe2O3) ≤ 0.5. Further studies of melting characteristics (deposition rate, spattering factor, etc.), melting-energy characteristics (melt-off coefficient CM and deposition rate coefficient Cd), and efficiency showed the efficiency of using exothermic addition with combined oxidizer of Al-CuO-Fe2O3 system. The study showed high arc stability of the hardfacing process, an increase in deposition efficiency (De), and a decrease in spattering loss, which increased deposition rate from 4.73 kg·h−1 to 6.42 kg·h−1 compared to exothermic addition with simple Al-Fe2O3 system. Analysis of weld bead morphology showed improvement in weld bead parameters. The results showed high energy efficiency and productivity of the welding/hardfacing process with the introduction of exothermic addition with combined oxidizer of CuO-Fe2O3-Al system at the following share of copper oxide in combined oxidizer CuO/(CuO + Fe2O3) = 0.5–0.6. [ABSTRACT FROM AUTHOR]

The paper presents the results of design and experimental studies carried out to modernize welding equipment to increase the reliability of operation in site conditions and improve ergonomic performance. The results of improving the technology and technique of welding vertical joints with forced weld formation in order to increase the efficiency of the process and expand its technological capabilities, as well as improve the sanitary and hygienic working conditions of the welder-operator are presented. The A-1150 and AD343 machines were modernized and prototypes of the machines were manufactured to create new specialized assembly welding equipment based on a modern element base in compliance with ergonomic requirements. The study of the macrostructure of the welded joints showed that the weld metal is dense, and no defects in the form of lacks of fusion, cracks, pores, nonmetallic inclusions, etc. were found. The main advantages of the proposed method compared to ESW and the method of welding with forced flux-cored wire formation are shown. The technology and equipment for submerged arc welding with forced formation of vertical joints of low-carbon low-alloy steels with a thickness of 12-80 mm have been developed and successfully implemented in factory and site conditions. [ABSTRACT FROM AUTHOR]

Welding is key sector in the manufacturing industry, and plays a critical role in making possible joints of different materials is achievable. Nevertheless, certain attributes of the welding process must be addressed, to ensure joints durable and reliable are produced. Hence, the objective of this paper is to evaluate the influence of heat input on the mechanical properties of a Tungsten Inert Gas (TIG) welded joint. Data obtained reveals that the most stable bead width is recorded at a low heat input. Therefore, maintaining and controlling the heat input is capable of guaranteeing the value of the bead width. Also the relatiobship between critical weld properties, which is the bead width and the tensile strength, as obtained from variation arising from the heat input, shows that the most maximum bead width is recorded at a very high tensile strength. An indication that the heat input has a corresponding effect on the bead width and tensile strength of the weld.

The use of a vent on a gas stove affects the mixing of air with fuel. This study examines the effect of different vent diameters on the performance of Dimethyl Ether (DME) gas-fueled stoves. A nozzle with variations in vent diameter of 3 mm, 2 mm, 1 mm, and no vent with a nozzle diameter of 0.96 mm at each vent. Installed on the fuel ignition system, the flame, heat intake, and combustion efficiency were tested. From the test results at a pressure of 280 mmH2O, the highest flame noise value after shutdown was obtained at the nozzle with a 1 mm vent which amounted to 64.2 dB, the highest heat intake value at the nozzle with a 1 mm vent which amounted to 1.6625 kW, and the highest efficiency value at the nozzle with a 3 mm vent which amounted to 59.135%.

The self‐developed Q960 high‐strength steel solid wire with different heat input is welded by MIG welding to solve the problem of insufficient low‐temperature toughness of Q960 steel weld. The effect of heat input on the microstructure and mechanical properties of butt welding deposited metal is studied in depth. The results show that the microstructure of deposited metal is composed of granular bainite (GB), degenerate upper bainite (DUB), martensite (M), and acicular ferrite (AF). DUB and M play key roles as strengthening phases, whereas GB and AF serve as primary toughening phases. Elevated heat input leads to a progressively rougher microstructure in the deposited metal. AF and DUB increase first and then decrease, GB increases and M decreases slightly. The inclusions conducive to AF nucleation are mainly composed of oxides of Mn, Si, Ti, and Mn sulfide with sizes between 100 and 500 nm. At a 14 kJ cm−1 heat input, the complex phase microstructure effectively refines the grain, and the high‐angle grain boundaries and ferrite interlocking structure optimize the strength and toughness balance of the deposited metals. The tensile strength measures 958 MPa, with the highest elongation at 19% and an average impact toughness of 50 J at −40 °C. [ABSTRACT FROM AUTHOR]

The lap welding process for 304L stainless steel welded using the pulsed gas tungsten arc welding (P-GTAW) procedure was studied, and the effects of the pulse welding parameters (the peak current, background current, duty cycle, pulse frequency, and welding speed) on the macroscopic morphology, microstructure, and mechanical properties of the resultant lap joints were investigated. Tensile tests, hardness measurements, and SEM/EDS/XRD analyses were conducted to reveal the characterization of the joint. The relationships between the welding parameters; certain joint characteristic dimensions (the weld width, D; the weld width on the lower plate, La; the weld depth on the lower plate, P; and the minimum fusion radius, R); and the maximum tensile bearing capacity were studied. The weld zone was primarily composed of vermicular ferrite, skeletal ferrite, and austenite, and no obvious welding defects, precipitation, or phase transformations were evident in the weld. Microhardness tests demonstrated that the weld microhardness was highest in the base metal zone and lowest in the weld zone. As the heat input increased, the average microhardness decreased. The hardness difference reached 17.6 Hv10 due to the uneven grain size and the transformation of the structure to ferrite in the weld. The fracture location in welded joints varied as the heat input changed. In some parameter combinations, the weld tensile strength was significantly higher than that of the base material, with fractures occurring in the weld. Scanning electron microscopy results exhibited an obvious dimple morphology, which is a typical form of ductile fracture. XRD revealed no significant phase changes in the weld zone, with a higher intensity of the austenite diffraction peaks compared to the ferrite diffraction peaks. [ABSTRACT FROM AUTHOR]

Welded T-joints of 945 shipbuilding steel are widely used in plate-beam connections, and their impact toughness directly affects the service life of shipboard structural components. However, current research efforts have primarily focused on the static mechanical properties of welded T-joints, with few scholars investigating the impact properties of welded T-joints under dynamic loading conditions. In this paper, laser-MAG hybrid welding of 945 shipbuilding steel T-joints is utilized to study the effects of heat input on the microstructure evolution and dynamic mechanical properties of welded T-joints. The results show that the increase in heat input results in a decrease in the cooling rate, which promotes the formation of lath martensite in weld metal and the formation of granular and lath bainite in coarse grain heat affected zone (HAZ). Concurrently, the higher heat input increases the width of the HAZ and leads to grain coarsening, resulting in a 298.9% increase in average grain area when the heat input rises from 12.1 to 14.6 kJ/cm. The changes in martensite content and morphology result in a reduction in the microhardness of welded T-joints. The HAZ becomes the most vulnerable region to dynamic impact loading, and the higher heat input leads to ductile fracture. Compared to high heat input, the drop hammer acceleration decreases by 34.0%, the maximum displacement increases by 45.9%, and the fracture energy increases by 43.1%, for low heat input. The changes in the drop hammer impact metrics further illustrate that welded T-joints with lower heat input are favorable for improving impact toughness. [ABSTRACT FROM AUTHOR]

This study investigates the impact of heat input, generated during friction stir welding, on the microstructure, mechanical properties, and corrosion resistance of dissimilar joints between A390-10 wt.% SiC composite and AA2024-T6 aluminum alloy. Welds were created using two rotational speeds: 600 rpm and 1600 rpm, while maintaining a constant traverse speed of 60 mm/min and employing a triangular pin tool. The results reveal that increasing the heat input from 125 to 354 J/mm leads to enhanced mixing in the stir zone, resulting in the formation of a layered structure. The stir zone area increases by 23% with the rise in heat input from 125 to 354 J/mm. Moreover, as the heat input and plastic strain in the stir zone increase, the particle size decreases by 31%, and their distribution becomes more uniform. Furthermore, an increase in heat input leads to the formation of coarser precipitates and particles on both the advancing and retreating sides, regardless of the type of precipitates formed. Conversely, reducing the heat input from 354 to 125 J/mm results in achieving maximum hardness (165.3 ± 2.3 HV0.1), yield strength (410.3 ± 11.3 MPa), ultimate tensile strength (514.5 ± 10.4 MPa), and minimum corrosion rate (0.41 mm/year). [ABSTRACT FROM AUTHOR]

ER2209 type welding consumable was used for welding overlay deposit on 2205 duplex stainless steel plate through gas metal arc welding (GMAW) at different heat inputs. The research focused on analyzing the effect of arc energy on the microstructure of the welded joint, as well as evaluating the corrosion behavior of the weld metal in a 3.5 wt% NaCl solution. The results show that the arc energy has a visible effect on the content of ferrite (δ) and austenite (γ) phases, which distinctly affects the corrosion resistance of the weld metal. It was found that the grain boundary austenite, Widmanstätten austenite, and intergranular austenite were present in all the weld metals, and the weld metal formed with a heat input of 2.206 kJ/mm had a high corrosion performance due to the high austenite content and the presence of a large content of intergranular austenite phases. [ABSTRACT FROM AUTHOR]

With the advancement of the manufacturing industry, performing submerged arc welding subject to varying welding heat inputs has become essential. However, traditional thermodynamic models are insufficient for predicting the effect of welding heat input on elemental transfer behavior. This study aims to develop a model via CALPHAD technology to predict the influence of heat input on essential elements such as O, Si, and Mn when typical SiO2-bearing fluxes are employed. The predicted data demonstrate that the proposed model effectively forecasts changes in elemental transfer behavior induced by varying welding heat inputs. Furthermore, the study discusses the thermodynamic factors affecting elemental transfer behavior under different heat inputs, supported by both measured compositions and thermodynamic data. These insights may provide theoretical and technical support for flux design, welding material matching, and composition prediction under various heat input conditions subject to submerged arc welding processes when SiO2-bearing fluxes are employed. [ABSTRACT FROM AUTHOR]

Nano-diamond (ND) is a special ultrafine reinforcement whose agglomeration properties and weak interfacial bonding limit its application in aluminum matrix composites. This study used the additive friction stir deposition (AFSD) technique to produce AA5083-H321/2.5 wt% nano TiN/ND additive manufacturing deposition hybrid composite parts (AMDCPs) and a non-composite part (AMDNCP) was also deposited for comparative analysis. The aim was to improve the microstructure and examine the effect of the deposition process parameters, which include 900, 1250, and 1600 rpm rod rotation speed and 5 and 12 mm/min feed rate. The AFSD process parameters were used to calculate the heat input. The consumable rod and AMD parts were evaluated for their macrostructure, microstructure, macro-hardness, tribological, and corrosion properties. The microstructural features were examined using an OM, XRD, and SEM equipped with an EDS. The worn and corrosion surface morphology was investigated using SEM, and hardness was also evaluated as contour maps. The results show that defect-free deposited multilayer AA5083-nano TiN/ND hybrid composite parts were successfully manufactured, and analysis revealed a lower D/H ratio, well-bonded layers, homogeneously distributed TiN/ND and fragmented IMC components, and equiaxed refined grain microstructures. The deposited composites via AFSD showed a lower corrosion rate, higher hardness, and wear resistance than the deposited AA5083 consumable rod and AMDNCP. The AMDP C900-12 demonstrates an optimized deposition process parameter (900 rpm, 12 mm/min) with superior properties, including an increase in hardness by 9.3%, a reduction in grain size by 54%, and a decrease in corrosion rate by 45.2% related to the AMDNC part.

This work optimizes the current (I), voltage (V), flow rate (F), and arc gap (G) of the gas tungsten arc welding (GTAW) of the Ti40A titanium alloy to decrease the heat input (HI) and improve the ultimate tensile strength (TS) and micro-hardness (MH). The radial basis function network (RBFN) was utilized to present performance measures, while weighted principal component analysis (WPCA) and an adaptive nondominated sorting genetic algorithm II (ANSGA-II) were applied to estimate the weights and generate optimal points. The evaluation via an area-based method of ranking (EAMR) was employed to determine the best solution. The results indicated that the optimal I, V, F, and G are 89 A, 23 V, 20 L/min, and 1.5 mm, respectively. The improvements in the TS and MH were 1.2 % and 19.8 %, respectively, while the HI was saved by 18.4 %. The RBFN models provided acceptable accuracy for prediction purposes. The ANSGA-II provides better optimality than the conventional NSGA-II. The HI, TS, and MH of the practical GTAW Ti40A could be enhanced using optimality. The optimization method could be utilized to deal with optimization problems for not only other GTAW operations but also other machining processes. [ABSTRACT FROM AUTHOR]