Welding Metallurgy of
01 Jan 1987-
About: The article was published on 1987-01-01 and is currently open access. It has received 991 citations till now. The article focuses on the topics: Welding.
Citations
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TL;DR: In this article, the grain structure of laser welded AlMgSi-alloys was varied by adapting the welding parameters and alloying additives, and the hot cracking susceptibility was determined by the critical strain rate, m...
Abstract: The grain structure of laser welded AlMgSi-alloys was varied by adapting the welding parameters and alloying additives. The hot cracking susceptibility was determined by the critical strain rate, m...
34 citations
TL;DR: In this article, hollow-laser beam melting deposition with internal powder feeding (HLB-MD-IPF) and regular Gaussian beam were compared to explore the effect of laser beam shape on the quality of coatings.
Abstract: Compared with the Gaussian laser beam, the ring-shaped laser beam has the advantages of uniform energy distribution and small temperature gradient. During the laser melting deposition, the ring-shaped beam can produce smaller residual stress in the workpiece, meanwhile avoids excessive sintering and dilution, reduces the heat accumulation, refines the grain size and improves the surface quality of the coating. In this study, hollow-laser beam melting deposition with internal powder feeding (HLB-MD-IPF) and regular Gaussian beam were compared to explore the effect of laser beam shape on the quality of coatings. The microhardness and electrochemical corrosion performance of the 316 stainless steel coatings prepared by different processing parameters were studied. The intrinsic mechanism of the performance difference was analyzed through microstructure and element distribution, and compared with the traditional Gaussian beam. In HLB-MD-IPF, the maximum microhardness was obtained with laser scanning speed of 12 mm/s, powder delivery rate of 1.6 rpm and laser power of 700 W, respectively. The average microhardness of the coatings prepared by different processes was between 270 and 310HV0.2. It was found that the microhardness of the coating decreased with the coarsening of the microstructure. Our results showed that with the same processing parameters, the microstructure prepared by the HLB-MD-IPF was obviously finer than those obtained from the Gaussian beam.
34 citations
TL;DR: In this paper, the authors developed welding procedures for autogenous CO2 and Nd-YAG (continuous mode) laser beam welding of 5754-O aluminium alloy and evaluated the mechanical and microstructural characteristics of the welded joints using tensile tests, microhardness tests, optical microscopy, and chemical analysis.
Abstract: Federal regulations have recently been enacted to reduce significantly the atmospheric pollution caused by motor vehicles. This has compelled automotive manufacturers to improve the fuel efficiency of cars and light trucks by using lightweight materials such as aluminium. The focus of the present work is to develop welding procedures for autogenous CO2 (continuous mode) and Nd–YAG (continuous mode) laser beam welding of 5754–O aluminium alloy. The mechanical and microstructural characteristics of the welded joints were evaluated using tensile tests, microhardness tests, optical microscopy, and chemical analysis. Results indicate that this alloy can be autogenously laser welded with full penetration, minimum surface discontinuities, and little if any loss of magnesium through vaporisation from the fusion zone. The total elongation (all weld metal) in the longitudinal direction for 5754–O laser welds produced using 5 kW CO2 and 3 kW continuous wave (CW) Nd–YAG shows a slight decrease with increasing...
34 citations
TL;DR: In this article, the effects of single component oxide fluxes in the TIG process on surface appearance, weld morphology, microstructures and micro-hardness during welding of 6mm thick low activation ferritic/martensitic (LAFM) steel were investigated.
Abstract: The present study is to investigate the effects of the single component oxide fluxes in the TIG process on surface appearance, weld morphology, microstructures and micro-hardness during welding of 6 mm thick low activation ferritic/martensitic (LAFM) steel. Herein, a novel variant of the autogenous TIG welding, wherein oxide powders such as CaO, CrO3, Fe2O3, MnO2, TiO2, and ZnO were applied through a thin layer before welding to produce a bead-on-plate joint. Experimental results indicated that activated TIG (A-TIG) process could increase the joint penetration and weld depth-to-width ratio (D/w) of LAFM steel weldment using CaO, Fe2O3, MnO2, TiO2, and ZnO fluxes. However, under same welding conditions, full penetration was achieved with the use of fluxes Fe2O3 and TiO2. Accordingly, it was proposed that, there might certainly be a specific dominant mechanism capable of giving superior penetration, although complete penetration was achieved through multiple mechanisms. Additionally to consider the metallurgical respects of A-TIG process, Vickers micro-hardness test was performed and microstructure characterization was carried out using optical microscopy. No noticeable change in microstructure and micro-hardness values of the TIG and A-TIG weldment was observed. A composite mixture of fine and coarse martensite was observed in weld and HAZ region.
34 citations
Cites background from "Welding Metallurgy of"
...the dependency of surface tension on temperature and a reverse, trend was observed [31]....
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...Several researchers have reported different mechanisms responsible for deeper penetration such as Reversed Marangoni [26, 29], Arc constriction [23, 24, 26], electromagnetic forces [30], buoyancy forces [31] and aero-dynamic forces [31]....
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TL;DR: In this paper, a 3-step design guideline in Al-Mg dissimilar welding through addition of an interlayer and a case study of using pure Ni foil as a proof of concept is presented.
Abstract: This paper critically assesses the recent trends in aluminum-magnesium dissimilar welding and suggests a key design guideline to successfully improve the weld joint quality through addition of interlayer. First, the paper describes the main issue of incompatibility between these metals and considers the root cause of the problem, i.e., the Al-Mg-based intermetallic compounds (IMCs). It then reviews the recent trends of interlayer addition in various welding processes to mitigate Al-Mg IMCs. Focusing on laser welding, the paper finally proposes a 3-step design guideline in Al-Mg dissimilar welding through addition of an interlayer and presents a case study of using pure Ni foil as a proof of concept. The design guideline has shown to be an effective means to predict and prevent the formation of deleterious intermetallics.
33 citations
References
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TL;DR: In this article, the state of the art in selective laser sintering/melting (SLS/SLM) processing of aluminium powders is reviewed from different perspectives, including powder metallurgy (P/M), pulsed electric current (PECS), and laser welding of aluminium alloys.
1,172 citations
TL;DR: In this article, the authors show that the pre-existing dislocation network, which maintains its configuration during the entire plastic deformation, is an ideal modulator that is able to slow down but not entirely block the dislocation motion.
557 citations
TL;DR: In this article, the fundamental understanding of structure-properties relationship in automotive steels resistance spot welds is discussed. And a brief review of friction stir spot welding, as an alternative to RSW, is also included.
Abstract: Spot welding, particularly resistance spot welding (RSW), is a critical joining process in automotive industry. The development of advanced high strength steels for applications in automotive industry is accompanied with a challenge to better understand the physical and mechanical metallurgy of these materials during RSW. The present paper critically reviews the fundamental understanding of structure–properties relationship in automotive steels resistance spot welds. The focus is on the metallurgical characteristics, hardness–microstructure correlation, interfacial to pullout failure mode transition and mechanical performance of steel resistance spot welds under quasi-static, fatigue and impact loading conditions. A brief review of friction stir spot welding, as an alternative to RSW, is also included.
369 citations
TL;DR: In this article, a unified equation to compute the energy density is proposed to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.
369 citations
TL;DR: This study attempted to predict solidification defects by DNN regression with a small dataset that contains 487 data points and found that a pre-trained and fine-tuned DNN shows better generalization performance over shallow neural network, support vector machine, and DNN trained by conventional methods.
314 citations