Welding Metallurgy of

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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.

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Journal Article•DOI•

A review on selective laser sintering/melting (SLS/SLM) of aluminium alloy powders: Processing, microstructure, and properties

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E. O. Olakanmi¹, E. O. Olakanmi², Robert F. Cochrane¹, Kenneth Dalgarno³•Institutions (3)

University of Leeds¹, Federal University of Technology Minna², Newcastle University³

01 Oct 2015-Progress in Materials Science

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.

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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 Article•DOI•

Dislocation network in additive manufactured steel breaks strength–ductility trade-off

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Leifeng Liu¹, Qingqing Ding², Yuan Zhong¹, Ji Zou³, Jing Wu³, Yu-Lung Chiu³, Jixue Li², Ze Zhang², Qian Yu², Zhijian Shen¹ - Show less +6 more•Institutions (3)

Stockholm University¹, Zhejiang University², University of Birmingham³

06 Dec 2017-Materials Today

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.

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557 citations

Journal Article•DOI•

Critical review of automotive steels spot welding: process, structure and properties

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Majid Pouranvari¹, S. P. H. Marashi²•Institutions (2)

Islamic Azad University¹, Amirkabir University of Technology²

18 Nov 2013-Science and Technology of Welding and Joining

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.

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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.

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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 Article•DOI•

Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice

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João Pedro Oliveira¹, Telmo G. Santos¹, Rosa Maria Mendes Miranda¹•Institutions (1)

University of Lisbon¹

01 Jan 2020-Progress in Materials Science

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.

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369 citations

Journal Article•DOI•

Using deep neural network with small dataset to predict material defects

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Shuo Feng¹, Huiyu Zhou¹, Hongbiao Dong¹•Institutions (1)

University of Leicester¹

15 Jan 2019-Materials & Design

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.

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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 Article•DOI•

Solidification Cracking Susceptibility of Stainless Steels: New Test and Explanation

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Kun Liu, Ping Yu, Sindo Kou

01 Oct 2020-Welding Journal

TL;DR: In this paper, the susceptibility of austenitic, ferritic, and duplex stainless steels to solidification cracking was evaluated by the Transverse Motion Weldability (TMW) test.

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Abstract: The susceptibility of austenitic, ferritic, and duplex stain-less steels to solidification cracking was evaluated by the new Transverse Motion Weldability (TMW) test. The focus was on austenitic stainless steels. 304L and 316L were least susceptible, 321 was significantly more susceptible, and 310 was much more susceptible. However, some 321 welds were even less susceptible than 304L welds. These 321 welds were found to have much finer grains to better resist solidification cracking. Quenching 321 during welding revealed spontaneous grain refining could occur by heterogeneous nucleation. For 304L, 316L, and 310, a new explanation for the susceptibility was proposed based on the continuity of the liquid between columnar dendrites; a discontinuous, isolated liquid allows bonding between dendrites to occur early to better resist cracking. In 304L and 316L, the dendrite-boundary liquid was discontinuous and isolated, as revealed by quenching. The liquid was likely depleted by both fast back diffusion into -dendrites (body-centered cubic) and the L +  + reaction, which consumed L while forming . In 310, however, the dendrites were separated by a continuous liquid that prevented early bonding between them. Back diffusion into -dendrites (face-centered cubic) was much slower, and the L +  + reaction formed little . Quenching also revealed skeletal/lacy formed in 304L and 316L well after solidification ended; thus, skeletal/lacy did not resist solidification cracking, as had been widely believed for decades. The TMW test further demonstrated that both more sulfur and slower welding can increase susceptibility.

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13 citations

Journal Article•DOI•

Workpiece Property Effect on Resistance Spot Welding

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Je-Ee Ho¹, PengSheng Wei², Tzong-Huei Wu³•Institutions (3)

National Ilan University¹, National Sun Yat-sen University², Yung Ta Institute of Technology and Commerce³

01 Jun 2012-IEEE Transactions on Components, Packaging and Manufacturing Technology

TL;DR: In this article, the weldability of resistance spot welding affected by different thermal, physical, and metallurgical properties is extensively investigated by realistically computing transient mass, momentum, energy, species, and magnetic field intensity transport in the alloy workpieces and electrodes.

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Abstract: The weldability of resistance spot welding affected by different thermal, physical, and metallurgical properties is extensively investigated by realistically computing transient mass, momentum, energy, species, and magnetic field intensity transport in the alloy workpieces and electrodes. The properties considered are the thickness, radius, equilibrium partition coefficient of workpieces, electrode-to-workpiece electrical conductivity ratio, thermal conductivity ratio, and a joule heat-to-enthalpy change parameter. Resistance spot welding has been widely used in joining thin workpieces in various electronic packaging and manufacturing industries. Understanding of physical mechanisms for easily manipulating and controlling weld qualities in advance is important. This paper accounts for electromagnetic force, heat generations due to contact resistances at the electrode-workpiece interface and faying surface between workpieces, and temperature-dependent bulk resistance of the workpiece. The contact resistances are functions of hardness, temperature, electrode force, and surface condition. The computed results in general dimensionless expressions show that the welding is feasible or onset time is shortened by decreasing thickness, radius, equilibrium partition coefficient of the workpiece, and electrode-to-workpiece electrical conductivity and thermal conductivity ratios, and increasing the joule heat-to-enthalpy change parameter. The corresponding heat transfer and species patterns are also presented.

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13 citations

Journal Article•DOI•

Analysis of weld defects in similar and dissimilar resistance seam welding of aluminium, zinc and galvanised steel

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T. Mira-Aguiar¹, Ivan Galvão¹, Carlos Leitão¹, Dulce Maria Rodrigues¹•Institutions (1)

University of Coimbra¹

21 Apr 2015-Science and Technology of Welding and Joining

TL;DR: In this article, a microstructural characterisation of welds performed by resistance seam welding was carried out, with special focus on weld defect analysis, in order to perform a comparative weldability analysis, the welds were performed using similar welding procedures.

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Abstract: In the present investigation, a microstructural characterisation of welds performed by resistance seam welding was carried out, with special focus on weld defect analysis. In order to perform a comparative weldability analysis, the welds were performed using similar welding procedures. Similar welds in aluminium (5754-H22) and zinc (Zintek) alloys, as well as dissimilar welds between galvanised steel and zinc, were studied. The defective aluminium welds were found to be characterised by important grain growth inside an inhomogeneous nugget and by the presence of important voids and cracks. The zinc welds showed a well defined nugget, but with porosities and some cracks. In the dissimilar steel–zinc welds, important macroscopic defects were observed. Microstructural analysis evidenced the occurrence of melting at the zinc side of the welds; meanwhile, no microstructural modifications could be observed for the steel side. Defect formation, as well as weld morphologies, was related to the variation i...

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13 citations

A fundamental investigation of boundaries and structures in dissimilar metal welds

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Tracy Wendell Nelson¹•Institutions (1)

Ohio State University¹

01 Jan 1998

Abstract: AbstractCracking, or disbonding, along the fusion boundary in dissimilar metal welds has been a persistent problem, particularly in applications where austenitic alloys are clad on to structural steels for corrosion protection. Many failures in dissimilar metal welds occur as a result of cracking along a boundary that runs parallel to the fusion boundary in the adjacent weld metal. A preliminary investigation was undertaken to determine the nature and evolution of boundaries and structure in dissimilar metal welds using a simple ternary system composed of a pure iron substrate and a 70Ni–30Cu (Monel) filler metal. Changes in base metal dilution were found to alter the evolution of boundaries and structures near the fusion boundary dramatically. Optical metallography and electron microanalysis reveal that the resulting weld microstructures and boundaries are similar to those observed in engineering materials used for cladding and corrosion resistant overlay. Transmission electron diffraction analysis revea...

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13 citations

Journal Article•DOI•

Microstructure evolution and nucleation mechanism of Inconel 601H alloy welds by vibration-assisted GTAW

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Ze-long Wang¹, Zhentai Zheng¹, Li-bing Zhao¹, Yunfeng Lei¹, Kun Yang² - Show less +1 more•Institutions (2)

Hebei University of Technology¹, Tianjin University²

11 Jul 2018-International Journal of Minerals Metallurgy and Materials

TL;DR: In this article, to improve the hot-cracking resistance and mechanical properties of nickel-based alloy welded joints, sodium thiosulfate was used to simulate crystallization, enabling the nucleation mechanism under mechanical vibration to be investigated.

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Abstract: Nickel-based alloys exhibit excellent high-temperature strength and oxidation resistance; however, because of coarse grains and severe segregation in their welding joints, these alloys exhibit increased susceptibility to hot cracking In this paper, to improve the hot-cracking resistance and mechanical properties of nickel-based alloy welded joints, sodium thiosulfate was used to simulate crystallization, enabling the nucleation mechanism under mechanical vibration to be investigated On the basis of the results, the grain refinement mechanism during the gas tungsten arc welding (GTAW) of Inconel 601H alloy under various vibration modes and parameters was investigated Compared with the GTAW process, the low-frequency mechanical vibration processes resulted in substantial grain refinement effects in the welds; thus, a higher hardness distribution was also achieved under the vibration conditions In addition, the γ' phase exhibited a dispersed distribution and segregation was improved in the welded joints with vibration assistance The results demonstrated that the generation of free crystals caused by vibration in the nucleation stage was the main mechanism of grain refinement Also, fine equiaxed grains and a dispersed γ' phase were found to improve the grain-boundary strength and reduce the segregation, contributing to preventing the initiation of welding hot cracking in nickel-based alloys

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13 citations