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ABSTRACT To accurately characterize the heat dissipation behavior of LF6 aluminum alloy laser arc composite welded joint under low cycle fatigue, two fatigue life prediction methods based on dissipated energy were proposed. The experimental investigation has revealed four stages in the evolution of surface temperature increment, including initial temperature increase, subsequent decline, attainment of thermal equilibrium, and sudden temperature escalation leading to failure. Based on the energy dissipation method, two models predicting lifespan of welded joints have been formulated. Model I incorporates the effects of stress amplitude and mean stress, on lifetime demonstrating a strong linear correlation particularly under high‐stress level according to experimental comparisons. Model II introduces a relationship between plastic strain amplitude and inherent dissipated energy to assess fatigue life of welded joints. Digital imaging correction technique has been utilized to quantify plastic strain amplitude. The predicted results from Model II agree well with experimental data. [ABSTRACT FROM AUTHOR]

Super duplex stainless steel UNS S32750 is widely used in marine industries, pulp and paper industries, and the offshore oil and gas industry. Welding manufacturing is one of the main manufacturing processes to make material into products in the above fields. It is of great importance to obtain high-quality welded UNS S32750 joints. The austenite content and ferrite content in UNS S32750 play an important role in determining UNS S32750 properties such as mechanical properties and corrosion resistance. However, the phase proportion between the ferrite phase and austenite phase in the welded joint will be changed during welding. Lots of research has been done on how to weld UNS S32750 and how to obtain welded joints with good quality. In this work, the recent studies on welding UNS S32750 are categorized based on the welding process. The welding process for UNS S32750 will be classified as gas tungsten arc welding, submerged arc welding, plasma arc welding, laser beam welding, electron beam welding, friction stir welding, and laser-MIG hybrid welding, and each will be reviewed in turn. The microstructure and properties of the joints welded using different welding processes will also be discussed. The critical challenge of balancing the two phases of austenite and ferrite in UNS S32750 welded joints will be discussed. This review about the welding process for UNS S32750 will provide people in the welding field with some advice on welding UNS S32750 super duplex stainless steel. [ABSTRACT FROM AUTHOR]

The impact of Flavin adenine dinucleotide (FAD) on sulfate-reducing bacteria (SRB) corrosion of a pipeline welded joint (WJ) was investigated under anaerobic condition in this paper. The results showed that the thickness of the corrosion product on heat affected zone (HAZ) was lower than that on base metal (BM) and welded zone (WZ), and the FAD addition enhanced the development of the protruding microbial tubercles on the WJ. The local corrosion degrees of the BM and WZ coupons were significantly higher than that of the HAZ coupon. Besides, the FAD addition simultaneously promoted local corrosion of all three zones of the WJ in the SRB inoculated environment, and the promotion role was much more pronounced on the WZ coupons. The selective promotion effect of FAD on SRB corrosion in the WJ was attributed to the special structure of the WZ, the selected SRB attachment and the FAD/FADH2 redox feedback cycle. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this article is to analyse the criteria for selecting a welding method for aluminium alloys from the two most popular conventional methods: Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG) and to assess their impact on the efficiency, quality and management of the welding process. Design/methodology/approach: The results presented in the article were obtained by analyzing the available literature as well as our own practical experience related to the management of production processes, taking into account quality and operational aspects. Findings: The selection of the welding method for aluminium alloys depends on many factors, including quality requirements and effective management of the production process. The criteria for selecting welding methods have been systematized and a comparative analysis of their impact on the efficiency and quality of welded joints has been conducted. Practical implications: The choice of welding method for aluminium alloys is influenced not only by technical aspects, but also by economic, management and quality aspects. Proper process management and awareness of the limitations, advantages and disadvantages of individual welding methods allows obtaining aluminium joints of the required quality and optimization of operating costs. Originality/value: The original achievement of the analysis is the establishment of comprehensive criteria for the selection of welding methods, taking into account quality management and the production process. The results can be useful to designers, manufacturers and managers, allowing for more effective management of the quality and efficiency of welding processes. [ABSTRACT FROM AUTHOR]

In this study, fracture behaviors of base metal and weld metal of ferritic steel welded joint in the thick wall pipeline for hydrogen transportation were investigated and the effects of hydrogen and specimen thickness (B) on fracture toughness were comprehensively considered in detail. A series of single edge notched tensile (SENT) tests for base metal and weld metal with B/W (width) ratio of 0.5, 1 and 2 were conducted with and without pre-electrochemical hydrogen charging, and crack tip opening displacement (CTOD) of δ m value was obtained by the double clip gauges method. It was found that fracture toughness (δ m) of base metal and weld metal decreased with increasing specimen thickness or hydrogenating, and δ m of hydrogenating specimen with B/W ratio of 2 was smallest. It was believed that large specimen thickness decreased fracture toughness by constraining plastic deformation at crack tip and restricting dislocations movement, while hydrogen promoted embrittlement by reducing cohesive energy of fracture. In the hydrogenating specimen with larger thickness, there was lower dislocation density near crack tip, leading to a decrease in trapped hydrogen and intensifying the cohesive energy reduction effect, which resulted in reduced δ m and the worse fracture toughness, and it means that hydrogen and specimen thickness synergistically affected fracture toughness. In addition, effect of thickness and hydrogen on decreasing fracture toughness was more pronounced for weld metal than base metal, which could be attributed to poorer plastic deformation ability of weld metal and lower dislocation density at crack tip. It is concluded that the hydrogen and thickness effects should be taken into account for the structural integrity evaluation of welded joint in hydrogen transportation pipeline. • Hydrogen coupled with specimen thickness severely deteriorated fracture toughness of base metal and weld metal. • Significant hydrogen embrittlement in thicker specimen was due to hydrogen, plastic deformation and dislocation interaction. • The hydrogen embrittlement effect was more pronounced for weld metal than base metal. • Structural integrity evaluation for welded pipelinemust take hydrogen and thickness into account. [ABSTRACT FROM AUTHOR]

In this paper, an isothermal diagram of the second phase formation in the Hastelloy G35 alloy was constructed to understand possible phase transformations during welding. A welded joint has been studied in three areas: fusion zone (FZ), the heat affected zone (HAZ), and the base metal (BM). The FZ is represented by a dendritic structure; in addition, σ-phase intermetallic compounds are present in the FZ and HAZ. Furthermore, the FZ and BM present similar hardness values, while the hardness increases in the HAZ. It has been established that thermal effects for different areas are characterized by different rates of increase up to 650°C. [ABSTRACT FROM AUTHOR]

To accurately evaluate the fatigue performance of a full‐scale deep‐water steel catenary riser (SCR) using small‐size specimens, six fatigue testing strategies were explored, considering the effect of welding residual stress. Through a comparison with the full‐scale resonant bending fatigue testing results, the most equivalent strategy using small‐scale specimens was identified. The results indicate that the test strategies applying constant stress underestimated the fatigue life, compared with that of a full‐scale specimen; meanwhile, fatigue life values obtained from the low‐stress ratio testing strategy were higher, particularly in the low‐stress range region. Comparatively, the fatigue lives obtained for the 100 mm‐wide specimens without cutting were higher in the high‐stress range region. The variable‐applied mean stress strategy using the 25 mm‐wide welded joint specimen was the most suitable for equivalence with the full‐scale fatigue testing, with only a 9.7% difference in the fatigue life testing results. The difference between the applied mean stress and the actual transverse welding residual stress under various fatigue testing strategies is the key factor affecting the equivalence of the fatigue testing results. Highlights: Fatigue testing results between the full‐scale and small‐scale pipeline welded joint specimens were compared.Six types of fatigue testing strategies were systematically explored using small‐scale welded joints properly.The variable mean stress fatigue testing strategy was proposed, and its equivalency with the full‐scale pipeline joint was confirmed.Mechanisms on the difference of fatigue testing results between full‐scale and small‐scale pipeline joints were analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium 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.)

Currently, ultrasonic methods for assessing the fatigue lifetime of various structural materials are being actively developed. Many steel constructions are made by welding. The weld heat-affected zone is the weak point of the construction, as it is most susceptible to destruction. Therefore, it is actually important to search for acoustic parameters that uniquely characterize the structural damage accumulation in the heat-affected zone of a welded joint in order to predict failure. In this work, the specimens were made from the base metal and the welded joint's heat-affected zone. The specimens were subjected to uniaxial tension–compression under a symmetrical cycle in the region of low-cycle fatigue with control of the strain amplitude. The propagation bulk velocities of longitudinal, shear waves and subsurface longitudinal critically refracted (LCR) waves during cyclic loading were studied. The acoustic birefringence of shear waves was calculated, and a similar parameter was proposed for longitudinal and LCR waves. The dependence of the elastic modulus ratio on the cycle ratio was obtained. It was shown that the acoustic parameters change most intensively in the heat-affected zone. According to the data of the C33/C55 ratio changes measured through the ultrasonic method, a formula for calculating the remaining fatigue life in the heat-affected zone was proposed. [ABSTRACT FROM AUTHOR]

The investigation into the impact of carbon dioxide shielded welding on the microstructure and corrosion resistance of clad rebars was conducted. The results show that Widmanstatten structure and carbide-free bainite organizations were observed in the heat-affected zone of the clad rebars and the width was about 4 mm. In the simulated marine environment, the corrosion rate of carbon steel rebar-welded joints was approximately 6 times higher than that of clad rebar-welded joints, exhibiting excellent corrosion resistance. Furthermore, the rust layer gradually transits from γ-FeOOH and α-FeOOH to Fe3O4, displaying densification. [ABSTRACT FROM AUTHOR]

Q345B/2205 dissimilar steel multi-layer multi-pass welded joints were prepared using gas metal arc welding (GMAW). The effects of heat inputs on the microstructures and properties of welded joints were studied. The morphology and composition distribution of Q345B base metal near the fusion line were investigated. The results showed that the welded joints under different heat inputs were all present “carbon depleted zone” and “carburized zones” on both sides of the Q345B base metal and transition layer interface. The microstructure of the “carburized zones” was composed of martensite phase and granular bainite phase. It was found that only the welded joints with heat inputs of 1.765 kJ/mm and 2.860 kJ/mm met the usage requirements. The corrosion behavior and characteristics of the welded joint with a heat input of 1.765 kJ/mm in a 3.5 wt % NaCl solution were investigated intensively. During the soaked process of 14 days, the total impedance value of the welded joint showed first increasing and then decreasing. The maximum value of 8.7 kΩ cm2 was obtained on the 5th day. As the soaked time increased, the corrosion products of the welded joint underwent the formation, thickening, cracking and detachment, which was the main reason of the change in the corrosion resistance. The research results of this article have significant implications for the application of low-alloy steel and stainless steel welded joints in engineering.

Currently, ultrasonic methods for assessing the fatigue lifetime of various structural materials are being actively developed. Many steel constructions are made by welding. The weld heat-affected zone is the weak point of the construction, as it is most susceptible to destruction. Therefore, it is actually important to search for acoustic parameters that uniquely characterize the structural damage accumulation in the heat-affected zone of a welded joint in order to predict failure. In this work, the specimens were made from the base metal and the welded joint’s heat-affected zone. The specimens were subjected to uniaxial tension–compression under a symmetrical cycle in the region of low-cycle fatigue with control of the strain amplitude. The propagation bulk velocities of longitudinal, shear waves and subsurface longitudinal critically refracted (LCR) waves during cyclic loading were studied. The acoustic birefringence of shear waves was calculated, and a similar parameter was proposed for longitudinal and LCR waves. The dependence of the elastic modulus ratio on the cycle ratio was obtained. It was shown that the acoustic parameters change most intensively in the heat-affected zone. According to the data of the C33/C55 ratio changes measured through the ultrasonic method, a formula for calculating the remaining fatigue life in the heat-affected zone was proposed.

The studies’ results of the high-speed electrothermal treatment effect on the structure and hardness of various zones of welded joints made of low-alloy structural steel 10ХСНД (10KhSND) are presented. It is shown that carrying out high-speed electrothermal treatment at 950–980 °C leads to the formation of a homogeneous, fine-grained ferrite-perlite microstructure with practically unchanged hardness values in all zones of the welded joint except for the weld root, where slightly higher values of microhardness are registered.

The fabrication of welded joints in steel sheets has become a focal point, especially in meeting the demands for interconnections within battery packs for electric vehicles (EVs). This study delves into the impact arising from the initiation arc during the micro-tungsten inert gas (TIG) welding of nickel-plated steel sheets. The investigation involved the manipulation of various current modulations and arc lengths. Notably, optimal results were achieved with a 5 mm arc length paired with a 25 A current modulation. Microstructural analysis, conducted through scanning electron microscopy (SEM), unveiled a higher penetration depth, contributing to a more extensive and shallower fusion zone at the interface between the filler metal and the base material. Tensile testing revealed impressive mechanical properties, with the ultimate tensile strength peaking at 90 N/mm2, a yield strength of 85 N/mm2, and the highest elastic modulus. This underscores the weld's robustness in withstanding applied loads and resisting fracture. Furthermore, the calculation of the lowest K factor at 1.0375 indicated a reduction in resistance across the specimen, resulting in enhanced conductivity. Micro-TIG welding emerges as an efficient method for nickel-plated steel in connecting individual battery cells to form a high-capacity battery pack. These interconnections ensure efficient current flow and maintain the overall integrity and performance of the battery pack. The reliability and quality of these interconnects directly affect the battery's efficiency, safety, and lifespan in EVs application. [ABSTRACT FROM AUTHOR]

X80 steel plays a pivotal role in the development of oil and gas pipelines; however, its welded joints, particularly the heat-affected zone (HAZ), are susceptible to stress corrosion cracking (SCC) due to their complex microstructures. This study investigates the SCC initiation mechanisms of X80 steel welded joints under practical pipeline conditions with varying levels of cathodic protection. The SCC behaviors were analyzed through electrochemical measurements, hydrogen permeation tests, and interrupted slow strain rate tensile tests (SSRTs) conducted in a near-neutral pH environment under different potential conditions (OCP, −1.1 VSCE, −1.2 VSCE). These behaviors were influenced by microstructure type, grain size, martensite/austenite (M/A) constituents, and dislocation density. The sub-zones of the weld exhibited differing SCC resistance, with the fine-grain (FG) HAZ, base metal (zone), welded metal (WM) zone, and coarse-grain (CG) HAZ in descending order. In particular, the presence of coarse grains, low dislocation density, and extensive M/A islands collectively increased corrosion susceptibility and SCC sensitivity in the CGHAZ compared to other sub-zones. The SCC initiation mechanisms of the sub-zones within the X80-steel welded joint were primarily anodic dissolution (AD) under open-circuit potential (OCP) condition, shifting to either hydrogen-enhanced local plasticity (HELP) or hydrogen embrittlement (HE) mechanisms at −1.1 VSCE or −1.2 VSCE, respectively. [ABSTRACT FROM AUTHOR]

Impact bending tests of rolled products, base metal and welded joints of pipes manufactured from low-carbon microalloyed steels are performed. The structure of different parts of welded joints is studied. Fractures of impact samples and compositions of nonmetallic inclusions on fracture surfaces are analyzed. The embrittling mechanisms and the causes of scattering of the impact toughness are considered. These may include coarse bainite within a large (deformed) austenite grain, a region near the fusion line with an unfavorable orientation of crystallographic cleavage planes {001} in a HFC welded joint, and large grains of grain-boundary ferrite in the weld and in the HAZ under arc welding. The critical grain size of the α-phase (the maximum fraction), at which the embrittling effect of the nonmetallic inclusions begins to be observed in the steels is 50 – 80 μm. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical properties, and high/very‐high cycle fatigue behaviors of 9Cr3W3Co turbine rotor steel and its welded joint were investigated. The welded nugget zone (WNZ) exhibited the highest microhardness value, followed by the heat‐affected zone (HAZ), while the base material (BM) showed the lowest hardness value. The WNZ exhibited a higher yield strength compared to the BM with reduced elongation, while maintaining similar ultimate tensile strength. The fatigue strength of the BM at 5 × 107 cycles is roughly 53.7% of the yield strength, whereas that of the WNZ increases to approximately 55.0%. In comparison to the fatigue strength of the BM at 5 × 107 cycles, the WNZ exhibits a notable increase of 10.5%. Smaller grain size and higher dislocation density were observed in the WNZ, which contributed to improved microhardness, yield strength, and fatigue resistance through grain boundary strengthening and dislocation hardening. Highlights: Microstructure and mechanical properties of 9Cr3W3Co steel welded joints were studied.Microhardness values of various zones are non‐uniform and the maximum value in WNZ.Dislocation and grain boundary strengthening contributed to strengthening in WNZ. [ABSTRACT FROM AUTHOR]

The damaged section of the pipe near a welded joint is investigated. The reason for metal loss of strength is established. It is shown that the height of seam root convexity has a decisive effect on component service life. [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.)

Objective To address the incomplete assessment system for seamless rail equipment conditions in China, it is necessary to establish an equipment condition assessment method for rail welded joints. Method The allowable deviations for the flatness of high-speed rail and welded joints specified by current Chinese regulations are elucidated. Taking a high-speed railway line for 13 years running in China as study case, the flatness data of the line rail welded joints is analyzed, and it is observed that the rail joint flatness detection data generally conforms to normal distribution. Based on the principles of normal distribution and confidence intervals, the mean value/standard deviation assessment and confidence level assessment two methods are compared. The rail welded joint equipment condition assessment method based on confidence level is proposed, along with the corresponding assessment criteria for high-speed railway rail equipment. Result & Conclusion This method can objectively and intuitively reflect rail welded joint equipment conditions, allowing accurate understanding of rail equipment conditions. The method can serve as a good theoretical basis for analyzing the law of changes in rail equipment, as well as formulating standards, plans, and strategies for major and medium maintenance.

In this paper, the effect of ER2209 multi-stranded wire compared to single wire on the microstructure and pitting resistance of 2205 duplex stainless steel submerged arc welded joints was studied using electron backscatter diffraction, scanning electron microscopy, energy spectrum analysis, electrochemistry and other detection techniques. Compared with single-wire welding of duplex stainless steel, the multi-stranded wire deposited more metal and doubled the welding efficiency with the same heat input, while increasing the elemental concentration of Ni in the weld metal and the proportion of austenite in the heat-affected zone. Compared with single-wire welding, multi-stranded wire welding promotes the diffusion of the main alloying elements (Cr, Mo, Ni, N) in the welded joint and improves the mechanical properties and pitting resistance of the welded joint. [ABSTRACT FROM AUTHOR]

Crack tip creep is a key parameter affecting the stress corrosion cracking (SCC) growth rate of nickel base alloy structural materials, significantly impacting the stress corrosion cracking rate of austenitic stainless steel and other materials. To explore the variation law of the crack tip creep field at different positions from the weld-seam of the welded joint, a numerical calculation model of the welded joint under different crack initiation positions was established based on alloy 600, and the crack tip stress field and creep were analyzed in detail. Results show that the unevenness of the material will cause obvious stress discontinuity at the crack tip of the material boundary; as the distance between the crack position and the weld interface increases, the stress of the crack tip before creep is affected by the mechanical properties of the base metal decreases. The creep rate of the weld side cracks gradually increases with the distance from the material interface. The minimum crack growth rate appears when the crack is located at the interface between the Ni-based alloy and base metal. The increased distance from the material interface increases the crack growth rate gradually. When the distance from the interface d > 0.1mm, the influence of mechanical properties on the growth rate is weakened. [ABSTRACT FROM AUTHOR]

The paper proposes a method for determining diagrams of the limiting cycle amplitudes of welded joints with steady-state residual tensile stresses based on the test results of small-sized specimens and presents the corresponding calculation dependencies. This technique is an express method for estimating the fatigue resistance characteristics of welded joints if full-scale tests are not feasible. The analysis of literature data for various types of welded joints shows a good fit of the experimental and calculated values of the endurance limits of welded joints of low-carbon steels with low-alloy, low-strength steels. It is shown that the inclined section of the diagram with steady-state residual stresses is shifted in parallel relative to the diagram of cycle amplitudes of welded specimens without residual stresses. It has been established that the diagrams of the limiting cycle amplitudes of welded joints with different values of the steady-state residual stresses end on a line where each point at different average cycle stresses corresponds to the minimum limiting cycle amplitude of the welded joint with its particular value of the ultimate steady-state residual stress, which ensures the realization of the ultimate stress cycle. With the same value of the steady-state residual stress, the endurance limit of welded joints decreases with an increase in the yield strength. It is shown that low values of steady- state residual stresses result in nearly the same endurance limit reduction of butt welded joints of steels of different strengths. In contrast, their higher values aggravate the endurance limit deterioration of steels with higher mechanical characteristics. [ABSTRACT FROM AUTHOR]

Martensitic low-alloy steels are widely used in machine construction. Due to their declared weldability, arc welding is most often used to join elements made of this type of steel. However, the high temperature associated with welding causes unfavourable changes in the microstructure, resulting in reduced abrasion resistance. Therefore, it is important to know the tribological properties of the welded joint. This article presents the results of a study on the abrasion wear resistance of a welded joint of an abrasion-resistant steel. This study tested a welded joint of an abrasive-resistant steel produced by the arc welding method. Wear testing of the welded joint was carried out under laboratory conditions by the ball-cratering method in the presence of abrasive slurry on the cross-section of the welded joint. Based on the test results, the change in the abrasive wear rate of the material as a function of the distance from the welded joint axis was determined. It was also found that the thermal processes accompanying welding caused structural changes that increased the wear rate index value. Adverse changes in the tribological properties of a welded material persist up to a distance of approx. 20 mm from the weld centre. [ABSTRACT FROM AUTHOR]

In modern industry, accurately assessing metal coupling by welding is critical. Given its reliability and other advantages, the eddy current test (ECT) is essential and commonly used in metal processing, especially welding. The classical ECT assesses the presence of discontinuities in the structure by monitoring the change in the probe's impedance. According to the wireless power transfer (WPT) theory, ECT members will exchange power wirelessly through mutual induction determined by inductance, capacitance, and resistance (LCR). The cracks will affect the mutual induction in the ECT's power exchange. Since LCRs are impedance components, the crack in the target will affect the system's mutual induction, as it did to the impedance in the classical ECT. This study applies the WPT model of ECT, implements system response analysis to assess cracks, and compares the results with classical ECT. The test piece is a metal arc-welded joint on SS 316 with an implanted notch on the welded joint to simulate the crack. A series of initial tests were performed to ensure the test piece was defects-free. Simulation and a frequency scan were performed to acquire a safe measurement. The result was that both the classical ECT and the system's response analysis successfully assessed the presence of cracks with excellent agreement. The system's response analysis yields a more rapid result than classical ECT. [ABSTRACT FROM AUTHOR]

The azimuth track is an important component of the radio telescope wheel–rail system. During operation, the azimuth track is inevitably subject to phenomena such as track wear, track fatigue cracks, and impact damage to welded joints, which can affect observation accuracy. The 110 m QiTai radio telescope (QTT) studied in this paper is the world's largest fully steerable radio telescope at present, and its track will bear the largest load ever. Since the welded joint of an azimuth track is the weakest part, an innovative welding method (multi-layer and multi-pass weld) is adopted for the thick welding section. Therefore, it is necessary to study the contact mechanical properties between the wheel and the azimuth track in this welded joint. In this study, tensile tests based on digital image correlation technology (DIC) and Vickers hardness tests are carried out in the metal zone (BM), heat-affected zone (HAZ), modified layer, and weld zone (WZ) of the welded joint, and the measured data are used to fit the elastic–plastic constitutive model for the different zones of the welded joint in the azimuth track. Based on the constitutive model established, a nonlinear finite element model is built and used to simulate the rolling mechanical performance between the wheel and azimuth track. Through the analysis of simulated data, we obtained the stress distribution of the track under different pre-designed loads and identified the locations most susceptible to damage during ordinary working conditions, braking conditions, and start-up conditions. The result can provide a significant theoretical basis for future research and for the monitoring of large track damage. [ABSTRACT FROM AUTHOR]

Wire beam electrode techniques and classical electrochemical techniques were used to investigate the effect of the area ratio of each part of the welded joint on the galvanic corrosion behavior. The results showed that the order of the corrosion current density of the different regions in the simulated X80 steel welded joint was as follows: coarse-grained heat-affected zone > fine-grained heat-affected zone > intercritical heat-affected zone > base metal > weld metal. As the area ratio of weld metal increased, the galvanic potential shifted positively, the maximum anode galvanic current density increased and the main anode galvanic effect increased. On the other hand, as the area ratio of the base metal and the heat-affected zone decreased, the coupled potential shifted negatively and the maximum anode galvanic current density decreased. The galvanic corrosion intensity of the simulated X80 steel welded joint increased as the area ratio of the weld metal decreased and increased as the area ratio of the heat-affected zone and base metal increased. To enhance corrosion resistance, it is advisable to choose a shape with a larger groove to increase the WM area in the welded joint. Additionally, selecting a welding method with lower heat input and a higher energy density can help reduce the HAZ area in the welded joint. [ABSTRACT FROM AUTHOR]

The mechanical properties of welded joints have a crucial impact on the safety of pipelines. This article focuses on examining the correlation between the microstructure and mechanical properties of welded joints of X65MS pipeline steel for sour service. The results indicate that the welding thermal cycle forms the microstructure consisting of acicular ferrite, granular bainite, and polygonal ferrite. The hardness across the joint ranges from 210 and 270 HV, peaking within the welded zone and decreasing towards the base metal (BM). At −40 °C, the welded zone shows the lowest impact energy of 53 J, while heat‐affected zones exhibit superior impact toughness exceeding 270 J with the highest impact energy of 326 J. This can be attributed to the exceptionally fine‐grained microstructure, a small quantity of small‐sized martensite‐austenite (M/A) constituents in the heat affected zone. As for the low toughness of the weld, the main factors can be attributed to the presence of large‐sized elongated M/A constituents and inclusions. [ABSTRACT FROM AUTHOR]

Copyright of Urban Mass Transit is the property of Urban Mass Transit 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 Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology 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 Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium 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.)

One of the most used techniques for making a continuous rail track is aluminothermic welding. This technique has its advantages in its simplicity, portability, and it does not require external energy when repairing or connecting tracks. One of the crucial parts when implementing this process is the mold design that influences the solidification of the casting. In this study three models were investigated that have varying positions of the feeders: asymmetrical mold, centered mold, and symmetrical mold. The focus of the paper is to determine how the position of the feeder effects the preheating of the side rails that would be welded together. This was carried out using NovaFlow & Solid CV and utilizing its sensor function. The rail was modeled after the 49E1 standard rail, and the preheating was carried out by simulating a burner at 1000 oC for 900 seconds. The asymmetrical model had a negligible increase in temperature, while the symmetrical and centered model were similar. One side rail was more heated than the other, which can be attributed to the positioning and shape of the burner source area.

Several factors affect the performance, manufacturing and assembly of metallic profiles: equipment, welding parameters and consumables. CSN Civil-300 steel profiles are widely used to obtain high-quality welded joints. Three factors in the welded joints need to remain nearly invariable and within predictable limits: distortion, corrosion and mechanical properties. However, industries still have problems with welding steel profiles, such as warping misalignment, misfit and poor mechanical properties. As a result, it is necessary to have a calibrated and affordable methodology for welding CSN Civil-300 steel profiles on the factory floor. Therefore, this study aims to analyse the mechanical performance of CSN Civil-300 steel profile–welded joints using a robot welding machine. A GMAW (metal active gas) welding process was applied to a CSN Civil-300 type U 100 × 50 profile, 3.0-mm thick, employing a Motoman UP6 robotic arm in butt joints, with and without dots. Two different rod electrode types were used (AWS ER70S-3 and ER70S-6), with a 75%Ar/25%CO2 shielding gas and current density welding set at 160.6 A and 20.5 V. A three-dimensional scanning methodology was adopted to investigate welded joint distortions. While salt spray accelerated, corrosion test was used to analyse deterioration. The mechanical properties were analysed by macrography, microhardness and chemical analyses in the heat-affected zone (HAZ). It was found a distortion displacement was lower than 450 μm on the sample's surface, and a mass loss of 10.1 μm/year was detected in terms of corrosion resistance. There was also evidence of chemical heterogeneity between the base metal and weld, mainly in the manganese content with an average reduction of 13% in microhardness measurements when AWS ER70S-3 electrode was used. By using calibrated welding parameters and a welding robot, it was possible to obtain mechanically resistant high-quality standardised welds. This procedure can be further improved by using other profile types to implement new robotic welding procedures. [ABSTRACT FROM AUTHOR]

With the development of society and urbanization, higher requirements have been put forward for the safety and seismic resistance of building structures. The fatigue strength and seismic performance of welded joints have received close attention, especially as a crucial part of building steel structure. This study used the finite element simulation method to analyze the stress-strain of welded joints in building steel structures, and explore the influence of residual stress on their seismic performance. A stress-strain calculation model for welded joints in building steel structures was studied and constructed, and the accuracy of the model was verified through numerical calculation methods. The results showed that the residual stress peaks of the horizontal and vertical directions of the V-groove welded joint structure were 475 MPa and 325 MPa, respectively, and the longitudinal residual stress peaks were 525 MPa and 425 MPa, respectively. The seismic performance of four different steel structural plates was Q 960 > Q 690 > Q 460 > Q 345 . In summary, the numerical simulation of residual stress in the seismic performance of welded joints in building steel structures, when based on the finite element method, makes a contribution of clear value to the field of seismic performance of welded joints in building steel structures. [ABSTRACT FROM AUTHOR]

The influence of specific microstructural characteristics on the properties of single-pass welding joints was assessed by optical processed images, transmission electron microscopy, microhardness measurements and corrosion tests conducted in various regions of the heat-affected zone (HAZ) in a lean duplex stainless steel. The welded joints were obtained with heat inputs of 1.5 and 2.5 kJ/mm using a gas metal arc welding (GMAW) process with a shielding gas enriched in Ar. Three selected regions in the HAZ showed different ferrite grain sizes and austenite fractions. The place in the welded joint where the HAZ was narrowest, and therefore experiences the highest cooling rate, is most prone to the formation of cubic CrN metastable nitrides. Conversely, the place where the HAZ was wider promotes the precipitation of stable Cr2N nitrides with more coalesced intragranular austenite (IGA) particles, where presumably random interfaces predominate. The HAZ region where the cooling rate was the highest presented more pitting corrosion resistance. [ABSTRACT FROM AUTHOR]

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The microstructure changes of TP347 austenitic stainless steel pipe welded joint after 1,050 °C solution heat treatment and 900 °C stabilization heat treatment are studied. The results show that in the as welded state, the grains in the heat affected zone grow and form different shapes ferrite and precipitate NbC and Cr carbides; after soild solution treatment, the ferrite content in the heat affected zone and fusion zone significantly decreases, and NbC with more dispersed distribution and smaller size is found; after solution treatment followed by stabilization heat treatment, the size of NbC further reduces, indicating that this heat treatment method can effectively disperse Nb carbide particles. Therefore, after solution heat treatment and stabilization heat treatment, TP347 steel undergoes ferrite transformation, NbC formation, and microstructure changes caused by reducing welding thermal cycle, which can effectively improve the material's resistance to intergranular corrosion. [ABSTRACT FROM AUTHOR]

The objective was to determine the structures of the zone in the welded joint of an ASTM A653CS Type B galvanized steel pipeline using electrical resistance welding seam. The tube was manufactured from a galvanized steel coil, with 52 mm of external diameter, a 3 mm wall thickness, and 350 mm length. A cross section was made through the joint to determine the structures and hardness. It was determined that the upper cord presents a fine-grained structure, with pearlite in an equiaxial ferritic and coarse-grained ferritic matrix; the inside cord showed a profile of ferrite and pearlite, where ferrite forms a network around and at the grain boundaries of the perlite, associated with the difference in temperatures in both areas. Both cords presented cracks associated with the displacement of the material that reaches the maximum temperature of 1 350 - 1400 °C; the edges of the plate are upset against each other with a hardness between 243 HV and 253 HV. [ABSTRACT FROM AUTHOR]