Welding in the World最新文献

Ultrasonic metal welding (USMW) is a manufacturing technique widely employed in the automotive and aerospace industries due to its efficiency in joining similar as well as dissimilar metals. Despite its prevalence, the lack of effective in-line process monitoring methods has resulted in high scrap rates, product recalls due to unrecognized scrap or financial losses due to pseudo-scrap, limiting its application in more sensitive industries. This paper presents a novel thermoelectric effect-based method for in-line process monitoring of USMW processes. This approach utilizes the thermoelectric properties, that manifest at the junctions of dissimilar metals during welding to accurately measure the temperature of the weld zone without the need of additional thermocouples, pyrometers or infrared cameras. An experimental setup was developed to validate the thermoelectric-based temperature measurement methodology. Key to this approach is the detection of thermoelectric voltage developed due to thermo diffusion when dissimilar materials are joined. The experiments showed a strong correlation between the thermoelectric voltage and the mechanical strength of the welds, suggesting that this parameter can effectively predict the quality of the weld. In the trials, a series of welded samples was created under controlled conditions to measure the generated thermoelectric voltage and correlate it with ultimate tensile strength tests. The data were analyzed using Spearman’s correlation coefficients to determine the correlation of the thermoelectric signals and joint strength. Results indicate that the thermoelectric voltage measurements correlate highly with the joint strength, with a Spearman’s correlation coefficient of over 0.94, thereby providing a promising predictive metric for assessing weld quality.

Friction stir-based techniques (FSTs), originating from friction stir welding (FSW), represent a solid-state processing method catering to the demands of various industrial sectors for lightweight components with exceptional properties. These techniques have gained much more attraction by providing an opportunity to tailor the microstructure and enhance the performance and quality of produced welds and surfaces. While significant attention has historically been directed towards the FSW process, this review delves into the working principles of FSTs, exploring their influence on mechanical properties and microstructural characteristics of various materials. Additionally, emphasis is placed on elucidating the advancement of hybrid FSW processes for both similar and dissimilar metal components, aimed at enhancing welding quality through meticulous control of grain textures, structures, precipitation, and phase transformations. Finally, the review identifies current knowledge gaps and suggests future research directions. This review paper synthesises academic literature sourced from the Web of Science (WoS) and Scopus databases, supplemented by additional sources such as books from the last 15 years.

The effects of Cr addition on the microstructure, mechanical properties, and corrosion behavior of two weld metals containing Ti or Mo within the Ni-Cu alloys used in high-speed train bogies were investigated. The results show that Cr can increase the acicular ferrite (AF) by about 15%, reduce the primary ferrite (PF) and the ferrite with second phase aligned (FSP), and slightly increase the M-A constituents in the weld containing Ti. Cr addition scarcely alters the AF, leads to a decline in PF and an increase in FSP, and causes a substantial increase in M-A constituents from 0.4 to 2.5% in the as-welded zone containing Mo. Meanwhile, it was found that Cr addition negatively affects weld toughness in the weld containing Mo due to the increase in the proportion and size of M-A constituents and the coarsening of inclusions. Regarding the corrosion resistance, Cr addition can promote the absorption of Cr on the surface of inclusions. This is the main reason for the reduction of the initial corrosion rate of the weld containing Mo, while this effect is attenuated in the welds containing Ti. In addition, Cr addition can densify the inner and outer rust layers, thereby reducing the corrosion rate of the welding rust layer.

In this study, the stress corrosion cracking (SCC) behavior of friction stir welded (FSWed) Al 6061-T6 alloy 10 mm thick plate is investigated. The general corrosion resistance of the base alloy and welded joint is evaluated using a potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and immersion test in NaCl solution. SCC susceptibility is evaluated in 3.5% NaCl and 7.5% NaCl aqueous solution using a slow strain rate tensile (SSRT) test. Potentiodynamic polarization test results show that the FSWed joint experienced a higher corrosion rate (9.658 × 10⁻⁶ mmpy) compared to base metal (0.734 × 10⁻⁶ mmpy). EIS results show that the charge transfer resistance (R_ct) of the joint was higher (118 Ω) compared to base metal (242 Ω) which further confirms that the joint has a higher susceptibility to pitting corrosion. SEM results also show that the welded joint immersed for 168 h in a 3.5% chloride environment experienced higher pitting corrosion than the base metal, while EDX results confirm that the pitting occurred due to the anodic dissolution of Mg-Si particles within the Al matrix. SCC results show that FSWed joints tested in air, 3.5% and 7.5% NaCl environment, show maximum load vs. displacement of 23.5 kN vs. 23.5 mm, 20.9 kN vs. 20.9 mm, and 16.8 kN vs. 16.8 mm, respectively indicating a weakened SCC resistance to increasing chloride environment. Samples tested in a chloride environment during the SSRT test showed quasi-cleavage fracture, while samples tested in an air environment showed ductile-type fracture. The higher general corrosion rate and SCC susceptibility of FSWed joints are attributed to the inhomogeneous microstructure developed during welding and the anodic dissolution of intermetallic compounds.

This study investigates the impact of travel speed on the weld quality of AA7075-T651 aluminum alloy using the cold wire pulsed gas metal arc welding (CW-PGMAW) process. By maintaining a constant heat input of 0.4 kJ/mm while varying travel speed between 90 and 100 cm/min, the study examines the process’s influence on microstructure, porosity, and liquation cracking. Results demonstrate that CW-PGMAW effectively refines microstructure and reduces defect formation compared to conventional GMAW. While mechanical properties showed improvement, further optimization is necessary to achieve base metal equivalent properties. The findings contribute to the understanding of CW-PGMAW for challenging aluminum alloys and provide a foundation for future process enhancements.

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The hydrogen steel gas-shielded welding wire was utilized in the WAAM technique, and the microstructure, crystal structure, and properties of the parts generated by layer-wise deposition were analyzed and evaluated. The study revealed that the components exhibit good quality, devoid of significant defects, and demonstrate robust internal metallurgical bonding. The metallographic structure mainly consists of pearlite and ferrite. The distribution of microhardness in the parts is fairly consistent, with mean microhardness values of 196.6 HV_0.1 (transverse) and 196.7 HV_0.1 (longitudinal). The parts exhibit exceptional mechanical properties, with a transverse yield strength of 406 MPa, an elongation rate of 14.2%, and a longitudinal yield strength of 380 MPa, an elongation rate of 18.9%. At − 30 °C, the average transverse Charpy impact value is 95.7 J, and the average longitudinal is 117 J.

This study investigates the processing and analysis of laser-welded Hastelloy X (HX) alloy joints, which are widely used in high-temperature aerospace and nuclear applications. Laser beam welding (LBW) experiments were conducted on HX base metal using a CO₂ laser, following an L9 Orthogonal Array (OA) experimental matrix. Variables included laser power, focal length, and welding speed. ASTM-standard testing showed that weld bead characteristics and joint properties varied with parameters. The joint with 20 J/mm heat input achieved the highest tensile strength and ductility, with 93% efficiency. Microstructure and EBSD analyses revealed grain elongation and refinement in the weld zone (WZ). The corrosion behaviour of the joints was assessed using potentiostatic polarization, with corrosion rates ranging from 7.4 × 10⁻³ to 8.6 × 10⁻⁵ mm/year. The joint with 25 J/mm heat input exhibited the highest corrosion resistance. Consequently, a dry sliding wear test was conducted on that sample, varying applied load, sliding distance, and sliding velocity as per the L9 OA matrix. Results indicated that the wear test (30 N, 1.0 m/s, and 1000 m) had the highest coefficient of friction (COF), while the wear test (50 N, 2.0 m/s, and 1500 m) showed the greatest wear loss. Increased wear rate correlated with higher load and sliding distance, with weld speed affecting joint strength and laser power influencing corrosion and wear properties. Field emission scanning electron microscopy (FESEM) revealed grain boundary effects, corrosion pits from localized corrosion, and wear tracks with surface irregularities on the worn weld surfaces.

Laser welding offers distinct advantages over traditional methods: less heat impact, no filler metal needed, and strong weld penetration. It is efficient and cost-effective, perfect for joining materials like the stainless steel 301LN, and ideal for industries addressing climate change. This study delves into the impact of various operating parameters on weld quality, specifically focusing on microstructure and microhardness. Using the Taguchi method, it is designed an experimental setup to systematically analyze these factors. The microstructure analysis shows a unique grain structure in the weld bead and a small heat-affected zone (HAZ), indicating precise welding control. Weld penetration measurements correlated with specific operating parameters using microstructure imaging. The microhardness analysis further underlined the control over HAZ thickness, crucial for ensuring the integrity of the welded joint. Through analysis of variance (ANOVA), it is identified significant factors affecting physical properties, help to construct a mathematical model to quantify parameter influences accurately. Findings suggest that minimizing the focal spot diameter is key to optimizing weld penetration, albeit in a delicate balance with welding speed and laser power settings. Adjusting these parameters can also influence the chemical composition match between the weld bead and base material, crucial for structural integrity. For achieving the desired hardness close to the base material, specific parameter ranges are recommended: a beam oscillation amplitude of 1.45 mm, a beam oscillation amplitude between 2.82 and 2.97 kW, and a focal spot diameter above 0.34 mm. Findings offer practical insights for improving weld quality and efficiency in industrial applications.

The weld toe is known to be a critical point of fatigue failure in many welded constructions. Especially for research purposes but also for improving fatigue life predictions, the weld toes geometry is often described by a set of parameters, including the weld toe radius and the flank angle. There is no universal agreement on the definition of the geometry parameters as well as on measuring routines. To get an overview over used techniques and comparability between research labs, a comprehensive round robin study was conducted over the past years. Two measuring tasks were given to the participants. Part A: A machined specimen with well known geometry inspired by a cruciform joint was analyzed and the results were compared with the actual dimensions of the specimen. Part B: Welded specimens with unknown geometry were measured by the participants and the results were bench-marked against each other. The present study summarizes the findings of Part A. The study gives an overview over used measuring techniques, the influence of measuring equipment and the comparability of the results in the scientific community. Most of the participants achieved good results with their respective measuring methods for radii larger than 1 mm. Smaller radii tend to be overestimated.

This study uses a finite element method based simulation methodology for in-situ railhead repair welding to investigate how welding process parameters impact the repaired rail quality. The methodology includes material modeling with cyclic plasticity, phase transformations, transformation-induced plasticity, and multi-phase homogenization. The weld process modeling includes a 3D heat transfer analysis and a 2D Generalized Plane Strain (GPS) mechanical analysis. The Heat source model used in the thermal simulation is calibrated using measurements from a repair welding experiment. To assess the performance of the repaired rail, mechanical rolling contact simulations are performed to estimate the risk of fatigue crack initiation. The process parameter study is based on the Swedish stick-welding railhead repair procedure and focuses on factors affecting the repair quality, such as preheating and operation temperature conditions as well as variations in repair geometry. Significant findings highlight both the inherent robustness of the process and regions susceptible to parameter variations. Specifically, the powerful final zig-zag weld passes provide effective resilience against variations in additional heating, and the start and end stretches of the repair welding are the most susceptible to parameter variations. Chamfered and deeper cutout repair geometries are found to be effective in mitigating adverse effects. In agreement with field observations, the simulations identify the fusion zone of the base and weld filler material as the critical region of the repaired rail in operation. This is attributed to the integrated effects of unfavorable microstructures, longitudinal tensile residual stresses from repair welding, and tensile stresses during operational traffic loads.