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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Citations

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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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Dissertation•DOI•

Analysis of residual stress and fatigue crack propagation behaviour in laser welded aerospace Aluminium T-joints

[...]

Funda Seniz Bayraktar

01 Jan 2011

12 citations

Journal Article•DOI•

Effects of activating fluxes on pulsed laser beam welded AZ31 magnesium alloy

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Jun Shen¹, Lianzhou Wang², M L Zhao¹, Dan Wang¹, Nan Xu¹ - Show less +1 more•Institutions (2)

Chongqing University¹, Chinese Academy of Sciences²

01 Nov 2012-Science and Technology of Welding and Joining

TL;DR: In this article, the effects of activating fluxes on macromorphologies, microstructures and mechanical properties of low power pulse laser beam welding of AZ31 magnesium alloy joints were investigated by microstructural observations.

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Abstract: Effects of activating fluxes on macromorphologies, microstructures and mechanical properties of low power pulse laser beam welding of AZ31 magnesium alloy joints were investigated by microstructural observations and mechanical properties tests (including the ultimate tensile strength and hardness). The results showed that activating flux (SiO2) is more effective in improving the laser welded penetrations when the heat input is at a critical value (E = 53·42 J mm−1). Five typical fluxes (SiO2, TiO2, ZnCl2, CaCl2 and CaF2) all increased the weld penetrations and D/W ratios of the welded joints. The morphologies of grains in the band zones with fluxes are characterised by dendritic crystals. Moreover, the widths of the band zones with oxide and chloride fluxes are wider than that with fluorine flux. The mechanical properties of the welded joints with fluxes were lower than those without flux. The fracture surface of the welded joints with fluxes exhibited a character of a mixed fracture.

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12 citations

Understanding Process-Structure Relationship For Site-Specific Microstructure Control in Electron Beam Powder Bed Additive Manufacturing Process Using Numerical Modeling

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Narendran Raghavan

01 Jan 2017

TL;DR: In this article, the authors used Truchas, a solidi cation code developed at Los Alamos National Laboratory, to calculate the spatial and temporal variations of temperature gradient (G) and growth velocity (R) at the liquid-solid interface of the melt pool.

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Abstract: Additive Manufacturing (AM), the fabrication of 3-D parts from CAD models, is a disruptive technology that is transforming the manufacturing industry. In any manufacturing process, understanding the process-structure-property-performance (PSPP) linkage is crucial to predict the lifespan of the manufactured component. In the PSPP linkage, the solidi cation microstructure (liquid-solid phase transformation) is one of the important factors a ecting the mechanical property and performance of the additively manufactured components. During rapid solidi cation, the solidi cation microstructure is dictated by the thermal gradient (G) at the liquid-solid interface and velocity (R) of the liquid-solid interface. In this work, the transient heat transfer and uid ow within the molten pool is numerically analyzed using Truchas, a solidi cation code developed at Los Alamos National Laboratory. The spatial and temporal variations of temperature gradient (G) and growth velocity (R) at the liquid-solid interface of the melt pool were calculated using the data from numerical modeling. 1. The obtained transient knowledge from numerical modeling is used to design new melt scan strategies for an electron beam powder bed AM system (Arcam) and achieve the following. • Control the grain size of the columnar grains. • Control the grain morphology transition (Columnar to Equiaxed). 2. The e ect of build geometry on the grain morphology control has been reported. It is found that the scan parameters have to be modi ed as a function of geometry. The data from in-situ process monitoring (infrared imaging) is also analyzed to distinguish the underlying grain morphology.

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12 citations

Journal Article•DOI•

Mechanical and metallurgical properties of DP 1000 steel square butt welded joints with GMAW

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Ianto Cáceres Leite Rocha¹, Ivan Guerra Machado¹, Cintia Cristiane Petry Mazzaferro¹•Institutions (1)

Universidade Federal do Rio Grande do Sul¹

24 Dec 2014-International journal of engineering and technology

TL;DR: In this article, Gas Metal Arc Welding (GMAW) was used to study the influence of heat input (i.e. cooling rate) on mechanical/metallurgical properties of square butt welded joints.

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Abstract: In this work, Gas Metal Arc Welding (GMAW) was used to study the influence of heat input (i.e. cooling rate) on mechanical/metallurgical properties of square butt welded joints of DP 1000 sheets. The influence of filler metals of different strengths on the mechanical properties of joints was also tested. A significant decrease in hardness was observed in the Heat Affected Zone (HAZ) due to martensite tempering, in regions where peak temperature was close to isotherm AC1 (calculated in 735 o C for these steel); coincidently, fracture in every tensile test occurred in regions where martensite was tempered, even when a wire of less strength was used. It was noticed that the decrease in ultimate tensile and yield strength of base metal was inherent to welding. When minimum heat input was used, deterioration in mechanical properties was less pronounced, once degree of HAZ softening was smaller. Elongation of joints increased with increasing heat input.

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12 citations

Journal Article•DOI•

Oxide dispersion strengthened 304 L stainless steel produced by ink jetting and laser powder bed fusion

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Brian K. Paul¹, Kijoon Lee¹, Yujuan He¹, Milad Ghayoor¹, Chih-Hung Chang¹, Somayeh Pasebani¹ - Show less +2 more•Institutions (1)

Oregon State University¹

01 Jan 2020-CIRP Annals

TL;DR: In this article, a hybrid method to synthesize oxide dispersion strengthened (ODS) 304 L stainless steel (SS) alloy using a modified laser powder bed fusion (LPBF) machine is discussed.

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12 citations