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•

Viewpoint: metallurgical aspects of powder bed metal additive manufacturing

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Rainer J. Hebert¹•Institutions (1)

University of Connecticut¹

01 Feb 2016-Journal of Materials Science

TL;DR: The physical mechanisms of metal additive manufacturing are grounded in metallurgy, branching into laser physics and the physics of granular materials as mentioned in this paper, and the physical mechanisms control the effects of processing parameters on microstructures and properties of additively manufactured parts.

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Abstract: Metal additive manufacturing has emerged as a new manufacturing option for aerospace and biomedical applications. The many challenges that surround this new manufacturing technology fall into several different categories. The paper addresses one of these categories, the physical mechanisms that control the additive manufacturing process. Physical mechanisms control the effects of processing parameters on microstructures and properties of additively manufactured parts. Some mechanisms might not have been recognized, yet, and for those that are currently known, detailed quantitative predictions have to be established. The physical mechanisms of metal additive manufacturing are firmly grounded in metallurgy, branching into laser physics and the physics of granular materials. Powder bed additive manufacturing is described from the powder storage to post-processing and elements of metallurgy are highlighted that are relevant for the different aspects of the additive manufacturing process. These elements include the surface reactions on powder particles, the heating and melting behavior of the powder bed, solidification, and post-processing. This overview of the different metallurgical aspects to additive manufacturing is intended to help guide research efforts and it will also serve as a snapshot of the current understanding of powder bed additive manufacturing.

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163 citations

Journal Article•DOI•

Co-precipitation of nanoscale particles in steels with ultra-high strength for a new era

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Zengbao Jiao¹, Junhua Luan¹, Michael K Miller², Yip-Wah Chung³, C.T. Liu¹ - Show less +1 more•Institutions (3)

City University of Hong Kong¹, Oak Ridge National Laboratory², Northwestern University³

01 Apr 2017-Materials Today

TL;DR: In this paper, the authors highlight recent advances in computation-aided alloy design, nanostructural characterization, and unique properties of newly developed nanoscale co-precipitation-strengthened steels.

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147 citations

Journal Article•DOI•

Microstructural characterization and properties of selective laser melted maraging steel with different build directions

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Chaolin Tan¹, Chaolin Tan², Kesong Zhou², Min Kuang, Wenyou Ma, Tongchun Kuang² - Show less +2 more•Institutions (2)

University of Birmingham¹, South China University of Technology²

22 Oct 2018-Science and Technology of Advanced Materials

TL;DR: In this paper, a nearly fully dense grade 300 maraging steel was fabricated by selective laser melting (SLM) additive manufacturing with optimum laser parameters, and different heat treatments were elaborately applie...

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145 citations

Journal Article•DOI•

In situ measurement and modelling of austenite grain growth in a Ti/Nb microalloyed steel

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Mehran Maalekian¹, Rene Radis², Rene Radis³, Matthias Militzer¹, André Moreau⁴, Warren J. Poole¹ - Show less +2 more•Institutions (4)

University of British Columbia¹, Graz University of Technology², Vienna University of Technology³, National Research Council⁴

01 Feb 2012-Acta Materialia

TL;DR: In this article, a grain growth model was developed, which includes the pinning effect of precipitates present in the steel, and an approach was developed to estimate the initial distribution of precipitate in the as-received material and their dissolution kinetics.

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144 citations

Journal Article•DOI•

Marangoni convection and weld shape variations in Ar-O2 and Ar-CO2 shielded GTA welding

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Shanping Lu¹, Shanping Lu², Hidetoshi Fujii², Kiyoshi Nogi²•Institutions (2)

Chinese Academy of Sciences¹, Osaka University²

25 Aug 2004-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing

TL;DR: In this article, the role of the oxide layer on the Marangoni convection on the pool surface at elevated temperature has been investigated and it was shown that the heavy oxide layer inhibited the fluid flow induced by the MARANGONA convection and also became a barrier for the oxygen absorption into the molten weld pool.

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Abstract: Increasing the oxygen or the carbon dioxide concentration in the argon-based shielding gas leads to an increase in the weld metal oxygen content when the oxygen or carbon dioxide concentration is to be lower than 0.6 vol.% in the shielding gas. However, when the O2 or CO2 concentration is higher than 0.6 vol.% in the Ar-based shielding gas, the weld metal oxygen is maintained around 200 ppm–250 ppm. An inward Marangoni convection mode in the weld pool occurs when the weld metal oxygen content is more than 100 ppm. When it is lower than 100 ppm, the Marangoni convection would change to the outward direction and the weld shape varies from a deep narrow to a shallow wide shape. The effective ranges of O2 and CO2 concentrations for deep penetration are same. A heavy layer of oxides is formed when the O2 or CO2 concentration in the shielding gas is more than 0.6 vol.%. Based on the thermodynamic calculation of the equilibrium reactions of Fe, Si, Cr and Mn with oxygen in liquid iron for the oxide products, FeO, SiO2 ,C r 2O3 and MnO and the experimental oxygen content in the weld metal, Cr2O3 and SiO2 oxides are possibly formed at the periphery area of the liquid pool surface under the arc column during the welding process. One model is proposed to illustrate the role of the oxide layer on the Marangoni convection on the pool surface at elevated temperature. The heavy oxide layer inhibited the fluid flow induced by the Marangoni convection and also became a barrier for the oxygen absorption into the molten weld pool. © 2004 Elsevier B.V. All rights reserved.

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140 citations