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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 article, a systematic parametric study has been made in pulsed Nd:YAG laser welding to understand the energy transfer modes and four different energy transfer zones, namely conduction, transition, penetration and keyhole, have been identified.
Abstract: A systematic parametric study has been made in pulsed Nd:YAG laser welding to understand the energy transfer modes. Four different energy transfer zones, namely conduction, transition, penetration, and keyhole, have been identified. The traditional classification of energy transfer modes based on the power density value of 106 W/cm2 is not strictly applicable as the transfer mode varies with pulse duration. The threshold power density to form keyhole is not constant, but the threshold energy density has been found to be invariant around 2.4 kJ/cm2. The pulse duration has been optimized to be of about 8 ms to achieve welds of higher aspect ratio.

28 citations

Journal ArticleDOI
TL;DR: In this article, a Gleeble-simulated microstructure of the heat-affected zone (HAZ) of tungsten inert gas (TIG) welded grade 2205 duplex stainless steel (DSS) has been produced.

28 citations

Journal ArticleDOI
TL;DR: The effect of mechanical arc oscillation on the weld metal grain structure in mild steel gas tungsten arc welds has been studied in this paper, showing that the strength of welds made with arc oscillations was higher than those made without arc oscillators.
Abstract: The effect of mechanical arc oscillation on the weld metal grain structure in mild steel gas tungsten arc welds has been studied. For welds made without arc oscillation, columnar grains were observed in the weld metal; however, for the same welding parameters, the weld made with arc oscillation had smaller sized relatively equiaxed grains in the weld metal. The strengths for weld made with arc oscillation was higher than that for weld made without arc oscillation, with appreciable increase in ductility; this could be attributed to the reduction in grain size diameter due to arc oscillation. Lower weld metal hardness and increase in heat affected zone hardness was observed in weld made with arc oscillation; this could be attributed to increase in pro-eutectoid ferrite formation with absence of Widmanstatten ferrite structures in the weld metal and less coarsening of grains in the heat affected zone due to increased cooling rate.

28 citations

Journal ArticleDOI
TL;DR: In this article, electron beam and friction welds have been compared to determine the mechanism of corrosion behavior of similar and dissimilar metal welds of three classes of stainless steels, namely, AISI 304, FISI 430 and duplex stainless steel (AISI 2205).
Abstract: Pitting Corrosion behaviour of similar and dissimilar metal welds of three classes of stainless steels, namely, austenitic stainless steel (AISI 304), ferritic stainless steel (AISI 430) and duplex stainless steel (AISI 2205), has been studied. Three regions of the weldment, i.e. fusion zone, heat affected zone and unaffected parent metal, were subjected to corrosion studies. Electron beam and friction welds have been compared. Optical, scanning electron microscopy and electron probe analysis were carried out to determine the mechanism of corrosion behaviour. Dissimilar metal electron beam welds of austenitic–ferritic (A–F), ferritic–duplex (F–D) and austenitic–duplex stainless steel (A–D) welds contained coarse grains which are predominantly equiaxed on austenitic and duplex stainless steel side while they were columnar on the ferritic stainless steel side. Microstructural features in the central region of dissimilar stainless steel friction welds exhibit fine equiaxed grains due to dynamic recry...

27 citations