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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Open Access

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Journal Article•DOI•

Laser power coupling efficiency in conduction and keyhole welding of austenitic stainless steel

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Ashish Kumar Nath, R. Sridhar, P. Ganesh, Rakesh Kaul

01 Jun 2002-Sadhana-academy Proceedings in Engineering Sciences

TL;DR: In this article, the laser power utilized in the welding process was estimated using the experimental results and the dimensionless parameter model for laser welding; and also the energy balance equation model was studied.

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Abstract: Laser welding of thin sheets of AISI 304 stainless steel was carried out with high power CW CO2 laser. The laser power utilized in the welding process was estimated using the experimental results and the dimensionless parameter model for laser welding; and also the energy balance equation model. Variation of laser welding efficiency with welding speed and mode of welding was studied. Welding efficiency was high for high-speed conduction welding of thin sheets and also in keyhole welding process at high laser powers. Effect of pre-oxidization of the surface and powder as filler material on laser power coupling is also reported. The paper also discusses effect of microstructure on the cracking susceptibility of laser welds.

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42 citations

Journal Article•DOI•

Hot cracking in pulsed Nd:YAG laser welding of AA5456

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Hamidreza Hekmatjou¹, Homam Naffakh-Moosavy¹•Institutions (1)

Tarbiat Modares University¹

01 Jul 2018-Optics and Laser Technology

TL;DR: In this paper, a 700-W pulsed Nd:YAG laser welding was employed to weld 5456 aluminum alloy plates with thickness of 5.5mm, and it was found that hot cracks can be avoided by pulsed laser in preheated status.

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Abstract: A 700 W pulsed Nd:YAG laser welding was employed to weld 5456 aluminum alloy plates with thickness of 5 mm. The weld penetration and tendency of liquation cracking in the heat affected zone and solidification cracking in the weld metal are investigated. It is found that hot cracks can be avoided by pulsed laser in preheated status. Increasing the laser average power in fixed pulse frequency and pulse duration resulted in a significant reduction in hot cracking tendency in pulsed laser welding. Also, the hot cracking susceptibility is reduced with increasing pulse frequency up to 50 Hz in fixed average power and pulse duration. The hot cracking tendency can be decreased by pulse duration decrement to 6 ms in fixed average power and pulse frequency. The factors contributing to the prevention or reduction of hot cracks in laser welding of aluminum alloy 5456 are the reduction in cooling rate causing change in solidification mode from columnar to equiaxed grains, and backfilling of liquated grain boundaries. With a 0.4 mm beam diameter Nd:YAG pulsed laser at 300 W average power, 6 ms pulse duration, 20 Hz pulse frequency, 5 mm/s travel speed and 150 °C preheating temperature, hot crack-free weld cross sections were achieved.

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41 citations

Journal Article•DOI•

A review on the laser welding of coated 22MnB5 press-hardened steel and its impact on the production of tailor-welded blanks

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M. Shehryar Khan¹, M.H. Razmpoosh¹, Elliot Biro¹, Y. Zhou¹•Institutions (1)

University of Waterloo¹

26 Mar 2020-Science and Technology of Welding and Joining

TL;DR: In this article, the current demand for vehicles with high fuel efficiency, improved safety and enhanced crashworthiness qualities is being met by making use of high strength components with tailored mechanical components.

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Abstract: The current demand for vehicles with high fuel efficiency, improved safety and enhanced crashworthiness qualities is being met by making use of high strength components with tailored mechanical pro...

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41 citations

Journal Article•DOI•

Development and comparison of residual stress measurement on welds by various methods

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Aruna Bahadur, B. Ravi Kumar, A. Seshu Kumar, Gopal Sarkar, J. S. Rao - Show less +1 more

01 Feb 2004-Materials Science and Technology

TL;DR: In this paper, a controlled thermal severity test (CTS) was performed on mild steel plates bolted together, with anchor welds deposited on opposite sides, after cooling, bithermal and trithermal test welds were deposited one after the other.

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Abstract: Residual stress constitutes an integral part of the total stress acting on any component in service. It is imperative to determine residual stress to estimate the life of critical engineering components, especially those that are welded. The stresses caused by non-uniform temperature distribution due to welding and the effect of these multiaxial stresses upon service performance are discussed. A controlled thermal severity test (CTS) was performed on mild steel plates bolted together, with anchor welds deposited on opposite sides. After cooling, bithermal and trithermal test welds were deposited one after the other. Varying welding stresses were deliberately introduced by using different thicknesses of both plates to change the thermal severity numbers (TSN). The main experimental technique used here to determine the magnitude and nature of residual stress is based on X-ray diffraction (XRD). It was utilised to develop and standardise other techniques. The XRD method is based on the peak shiftin t...

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41 citations

Journal Article•DOI•

Effect of Energy Input on the Characteristic of AISI H13 and D2 Tool Steels Deposited by a Directed Energy Deposition Process

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Jun Seok Park¹, Joo Hyun Park², Min-Gyu Lee¹, Ji Hyun Sung¹, Kyoung Je Cha¹, Da Hye Kim¹ - Show less +2 more•Institutions (2)

KITECH¹, Hanyang University²

08 Mar 2016-Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science

TL;DR: In this article, the effect of energy input on the characteristics of H13 and D2 steels deposited by a direct metal tooling process based on the directed energy deposition (DED) process was investigated.

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Abstract: Among the many additive manufacturing technologies, the directed energy deposition (DED) process has attracted significant attention because of the application of metal products. Metal deposited by the DED process has different properties than wrought metal because of the rapid solidification rate, the high thermal gradient between the deposited metal and substrate, etc. Additionally, many operating parameters, such as laser power, beam diameter, traverse speed, and powder mass flow rate, must be considered since the characteristics of the deposited metal are affected by the operating parameters. In the present study, the effect of energy input on the characteristics of H13 and D2 steels deposited by a direct metal tooling process based on the DED process was investigated. In particular, we report that the hardness of the deposited H13 and D2 steels decreased with increasing energy input, which we discuss by considering microstructural observations and thermodynamics.

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41 citations