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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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Journal ArticleDOI
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


Cites background from "Welding Metallurgy of"

  • ...(......................................................3/)(16 33* VSL GSG ∆=∆ θπγ According to Kou [144] and Savage [145], growth of the solid in fusion welding is perceived as being initiated by epitaxial growth from the substrate and proceeds by competitive growth toward the center line of the weld....

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  • ...100 the predominant mechanism of solidification in fusion welding is the competitive growth in the weld fusion zone, Kou [144] identified and discussed the details of other mechanisms such as dendrite fragmentation, grain detachment, heterogeneous nucleation and surface nucl eatio that may tend can interrupt and/or dominate the solidification structure in fusion welding....

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  • ...According to Kou [144] and Savage [145], growth of the solid in fusion welding is...

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  • ...Whereas, the predominant mechanism of solidification in fusion welding is the competitive growth in the weld fusion zone, Kou [144] identified and discussed the details of other mechanisms such as dendrite fragmentation, grain detachment, heterogeneous nucleation and surface nucleatio that may tend can interrupt and/or dominate the solidification structure in fusion welding....

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Journal ArticleDOI
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

Journal ArticleDOI
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


Cites background from "Welding Metallurgy of"

  • ...Despite the fact that Schaeffler diagram predicts two phases (austenite plus ferrite) in the FZ of AISI 304 weld nugget microstructure, under rapid solidification conditions such as laser beam welding, a shift in solidification mode may occur.(90) It is generally believed that the change in solidification mode can often result in a fully austenitic microstructure compared to the two phase (ferrite plus austenite) microstructure that is commonly found after primary ferrite solidification....

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  • ...In coarse grained region, which is beside the FZ, both high cooling rate and large austenite grain size coupled with the formation of the carbon rich austenite promote the formation of the martensite.(90) Figure 15 shows the microstructure gradient in TRIP780 RSW....

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  • ...The HAZ in carbon steel weldments can be divided into three distinct subregions: (i) upper critical HAZ (UCHAZ): This region experiences peak temperatures above Ac3 transforming BM microstructure into austenite.(90) Depending on the peak temperature the supercritical HAZ can be divided to the following zones: coarse grained HAZ (CGHAZ) and fine grained HAZ....

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  • ...It is generally believed that the change in solidification mode can often result in a fully austenitic microstructure compared to the two phase (ferrite plus austenite) microstructure that is commonly found after primary ferrite solidification.(90,95,96) Although the change in solidification mode of stainless steel in RSW has not been studied yet, very high cooling rate in RSW process can explain the formation of a fully austenitic weld nugget, as it is the case for laser beam welding....

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  • ...If this temperature is above Mf, there can be untransformed austenite left in the FZ and it can redecompose to untempered martensite upon cooling to room temperature after tempering.(90) For a particular tempering time and tempering current, there is a minimum cooling time to achieve PF mode....

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Journal ArticleDOI
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

Journal ArticleDOI
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


Cites background from "Welding Metallurgy of"

  • ...Solidification crack is one of the most serious defects which occurs widely in welding [27,28], casting [29–31] and additive manufacturing (AM) [32,33], which occurs at the last stage of solidification when liquid films exist between dendrites boundaries where local strains cannot be accommodated by liquid feeding and solid deformation....

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References
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Journal ArticleDOI
TL;DR: In this paper, the effect of laser specific energy on the microstructure, micro-hardness and wear property of composite coatings was studied, and the results showed that the composite coating exhibited free from cracks and pores.
Abstract: In-situ formation of TiC, Ni3Ti and Ti2(Ni,Al) with CNTs reinforced Ti-based composite coatings were fabricated by laser alloying processing. The effect of laser specific energy on the microstructure, micro-hardness and wear property of the composite coatings were studied. The results showed that the composite coatings exhibited free from cracks and pores. Cypress leaf-like and flower-like TiC dendrites, as well as block-like Ti2(Ni,Al) and rod-like Ni3Ti intermetallic compounds were in-situ formed and distributed uniformly in the coating. With the increasing of laser specific energy, TiC dendrites coarsened and amount of TiC reduced. The micro-hardness and wear resistance of the coatings first increased and then decreased with the increasing of laser specific energy. When laser specific energy was controlled with 4.167–5 kJ/cm2, coatings with high micro-hardness and wear resistance were obtained. Wear resistance of the coatings were 2.3–6.9 times of that of substrate. Wear behavior of the dominant wear mechanism of the composite alloying coatings was adhesive wear, however, the Ti6Al4V substrate exhibited serious abrasive wear, adhesive wear and plastic deformation.

20 citations

Journal ArticleDOI
TL;DR: In this paper, a finite element model is used to carry out thermal analysis of bead-on-plate welding and the model followed the proposed five step strategies which were then built into a model to obtain temperature history at the positions of thermocouples.
Abstract: In this paper, finite element model is used to carry out thermal analysis of bead-on-plate welding. The model followed the proposed five step strategies which were then built into a model to obtain temperature history at the positions of thermocouples. Temperature field was also evaluated by comparing predicted weld bead with the actual weld bead. Using these proposed strategies, well matched temperature histories and temperature field have been obtained.

20 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of heat input using E 308 electrode (controlled by welding current, i.e., 70, 85 and 100 A) on microstructure, mechanical properties and corrosion behavior of low-nickel and 304 stainless steel (SS) weldments produced by shielded metal arc welding technique was investigated.
Abstract: The present research study investigates the effect of heat input using E 308 electrode (controlled by welding current, i.e., 70, 85 and 100 A) on microstructure, mechanical properties and corrosion behavior of low-nickel and 304 stainless steel (SS) weldments produced by shielded metal arc welding technique. SEM investigation shows that with the higher heat input, δ-ferrite content was reduced. Dendrite and inter-dendritic length is also reduced by lowering the heat input. For all the heat inputs, it is observed that δ-ferrite content was higher in 304 stainless steel (SS) as compared to that of low-nickel austenitic stainless steel (Cr-Mn SS). Considering the heat input for Cr-Mn SS, coarse grains were observed in the heat-affected zone region. For low heat input (LHI), tensile fracture surface has exhibited river-like pattern with dimple appearance. Corrosion studies show better pitting resistance for low heat input (LHI) samples due to higher δ-ferrite present in the weld region. Similarly, higher interphase corrosion resistance is observed in both the SS grades causing more dissolution in the LHI samples.

20 citations

Journal ArticleDOI
TL;DR: In this article, the effects of thermomechanical treatment on laser modified NiTi wires, while comparing them to the original base material, were investigated using a scanning electron microscope (SEM) and transmission electron microscopy (TEM).

19 citations

Journal ArticleDOI
TL;DR: In this article, the authors used ElectroSpark Deposition (ESD) to fabricate a 2024 aluminum alloy deposit on a similar substrate, which was characterized by the overlapping of layers with a mixed microstructure.
Abstract: ElectroSpark Deposition (ESD) is a pulsed micro-welding process that is capable of depositing wear and corrosion resistance deposit to repair, improve, and to extend the service life of the components and tools. Major new applications have taken place in gas turbine blades and steam turbine blade protection and repair, and in military, medical, metal-working, and recreational equipment applications. In this study, the ESD technique was exploited to fabricate 2024 aluminum alloy deposit on a similar substrate. The deposits were deposited using different process parameters. Heat input was varied on three levels. The outcoming microstructure was analyzed by optical and scanning electron microscopies. The deposit was characterized by the overlapping of layers with a mixed microstructure. The average hardness was independent from the process parameters. Both porosity inside the deposits and cracks at the deposit/substrate interface were detected. The porosity lowered with the heat input and increased the average length of cracks.

19 citations