Welding Metallurgy of

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Welding Metallurgy of

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•

Peak Stir Zone Temperatures during Friction Stir Processing

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Srinivasan Swaminathan¹, Keiichiro Oh-Ishi², Alexander P. Zhilyaev³, Christian B. Fuller¹, Blair London⁴, Murray W. Mahoney, Terry R. McNelley⁵ - Show less +3 more•Institutions (5)

General Electric¹, National Institute for Materials Science², Spanish National Research Council³, California Polytechnic State University⁴, Naval Postgraduate School⁵

01 Mar 2010-Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science

TL;DR: In this paper, a tool design with a smooth concave shoulder and a 12.7mm step-spiral pin was used for friction stir processing of NiAl bronze plates.

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Abstract: The stir zone (SZ) temperature cycle was measured during the friction stir processing (FSP) of NiAl bronze plates. The FSP was conducted using a tool design with a smooth concave shoulder and a 12.7-mm step-spiral pin. Temperature sensing was accomplished using sheathed thermocouples embedded in the tool path within the plates, while simultaneous optical pyrometry measurements of surface temperatures were also obtained. Peak SZ temperatures were 990 °C to 1015 °C (0.90 to 0.97 TMelt) and were not affected by preheating to 400 °C, although the dwell time above 900 °C was increased by the preheating. Thermocouple data suggested little variation in peak temperature across the SZ, although thermocouples initially located on the advancing sides and at the centerlines of the tool traverses were displaced to the retreating sides, precluding direct assessment of the temperature variation across the SZ. Microstructure-based estimates of local peak SZ temperatures have been made on these and on other similarly processed materials. Altogether, the peak-temperature determinations from these different measurement techniques are in close agreement.

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49 citations

Journal Article•DOI•

Influence of laser welding heat input on HAZ cracking in newly developed Haynes 282 superalloy

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L O Osoba¹, Olanrewaju A. Ojo¹•Institutions (1)

University of Manitoba¹

01 Apr 2012-Materials Science and Technology

TL;DR: In this article, a study of the cause of heat affected zone (HAZ) cracking and its dependence on heat input during laser beam welding of a newly developed γ′ precipitation strengthened nickel based superalloy Haynes 282 was performed.

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Abstract: A study of the cause of heat affected zone (HAZ) cracking and its dependence on heat input during laser beam welding of a newly developed γ′ precipitation strengthened nickel based superalloy Haynes 282 was performed. Careful microstructural study coupled with Gleeble thermomechanical simulation showed that HAZ cracking in the alloy is attributable to the degradation of hot ductility of the alloy due to subsolidus grain boundary liquation. A decrease in the magnitude of heat input during laser beam welding resulted in increased HAZ cracking. The cracking variation with heat input is discussed in relation to the time that the subsolidus HAZ region spent at peak temperatures and thermally generated stress during welding.

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47 citations

Journal Article•DOI•

Mechanical Properties and Microstructural Characterization of Cu-4.3 Pct Sn Fabricated by Selective Laser Melting

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Anthony P. Ventura¹, C. Austin Wade¹, C. Austin Wade², Gregory T. Pawlikowski³, Martin Bayes³, Masashi Watanabe¹, Wojciech Z. Misiolek¹ - Show less +3 more•Institutions (3)

Lehigh University¹, University of Manchester², TE Connectivity³

01 Jan 2017-Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science

TL;DR: In this article, the components were fabricated via selective laser melting (SLM) of prealloyed Cu-43 pct Sn powder and heat treated at 873 K and 1173 K (600 Â°C and 900 ÂC) for 1 hour.

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Abstract: Components were fabricated via selective laser melting (SLM) of prealloyed Cu-43 pct Sn powder and heat treated at 873 K and 1173 K (600 °C and 900 °C) for 1 hour Tensile testing, conductivity measurement, and detailed microstructural characterization were carried out on samples in the as-printed and heat-treated conditions Optimization of build parameters resulted in samples with around 97 pct density with a yield strength of 274 MPa, an electrical conductivity of 241 pct IACS, and an elongation of 56 pct Heat treatment resulted in lower yield strength with significant increases in ductility due to recrystallization and a decrease in dislocation density Tensile sample geometry and surface finish also showed a significant effect on measured yield strength but a negligible change in measured ductility Microstructural characterization indicated that grains primarily grow epitaxially with a submicron cellular solidification substructure Nanometer scale tin dioxide particles identified via X-ray diffraction were found throughout the structure in the tin-rich intercellular regions

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46 citations

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Hannu Hänninen, Pertti Aaltonen, Anssi Brederholm, Ulla Ehrnstén, Hans Gripenberg, Aki Toivonen, Pitkänen Jorma, Iikka Virkkunen - Show less +4 more

01 Jan 2006

TL;DR: In this article, the authors evaluated the properties of the nickel-base alloys, including the microstructure and microchemistry in the multi-pass nickel base alloy welds.

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Abstract: The operating experience of major nuclear power plant (NPP) pressure boundary components has recently shown that dissimilar metal weld joints can jeopardize the plant availability and safety because of increased incidences of environment-assisted cracking (EAC, PWSCC) of Alloy 600 and corresponding weld metals (Alloys 182/82). Alloy 690 and associated weld metals (Alloys 152/52) are widely used for repair and replacement of the affected thick-section components. The selection of new materials relies mainly on excellent laboratory results and short-term service experience. The long-term behaviour of these materials and their performance in the plant has still to be demonstrated. Weldability of the studied nickel-base materials is evaluated based on the results obtained for weld metals of different chromium contents. The susceptibility to hot cracking is examined as well as the PWSCC susceptibility in the reactor primary water based on the metallurgical properties of the nickel-base alloys. The microstructure and microchemistry in the multi-pass nickel-base alloy welds is very different than in the wrought and recrystallized nickel-base materials. Additionally, the thermal ageing experience of various nickel-base weld metals is discussed. Weld residual stresses and their role in PWSCC as well as surface stress improvement techniques for PWSCC mitigation are also reviewed. Finally the application, improvements and qualification of NDE for nickel-base weld locations are evaluated concerning the probes, techniques and scanning devices. The need for representative mock-ups for technique development and qualification is discussed. The technical basis for development of inspection requirements for dissimilar metal welds and efforts to qualify inspection procedures and personnel are also emphasized. Maintaining the structural integrity of the NPP and oil refinery main components throughout the service life in spite of the several possible ageing mechanisms related to the dissimilar metal welds is essential for plant safety and availability.

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46 citations

Journal Article•DOI•

Increase in oxidative stress levels following welding fume inhalation: a controlled human exposure study.

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Halshka Graczyk¹, Nastassja Lewinski¹, Nastassja Lewinski², Jiayuan Zhao¹, Jiayuan Zhao³, Jean-Jacques Sauvain¹, Guillaume Suarez¹, Pascal Wild⁴, Brigitta Danuser¹, Michael Riediker¹ - Show less +6 more•Institutions (4)

University of Lausanne¹, Virginia Commonwealth University², Harvard University³, Institut national de la recherche scientifique⁴

01 Dec 2015-Particle and Fibre Toxicology

TL;DR: A 60-min exposure to TIG welding fume in a controlled, well-ventilated setting induced acute oxidative stress at 3 h post exposure in healthy, non-smoking apprentice welders not chronically exposed to welding fumes.

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Abstract: Tungsten inert gas (TIG) welding represents one of the most widely used metal joining processes in industry. It has been shown to generate a large majority of particles at the nanoscale and to have low mass emission rates when compared to other types of welding. Despite evidence that TIG fume particles may produce reactive oxygen species (ROS), limited data is available for the time course changes of particle-associated oxidative stress in exposed TIG welders. Twenty non-smoking male welding apprentices were exposed to TIG welding fumes for 60 min under controlled, well-ventilated settings. Exhaled breathe condensate (EBC), blood and urine were collected before exposure, immediately after exposure, 1 h and 3 h post exposure. Volunteers participated in a control day to account for oxidative stress fluctuations due to circadian rhythm. Biological liquids were assessed for total reducing capacity, hydrogen peroxide (H2O2), malondialdehyde (MDA), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) concentrations at each time point. A linear mixed model was used to assess within day and between day differences. Significant increases in the measured biomarkers were found at 3 h post exposure. At 3 h post exposure, we found a 24 % increase in plasma-H2O2 concentrations ([95%CI: 4 % to 46 %], p = 0.01); a 91 % increase in urinary-H2O2 ([2 % to 258 %], p = 0.04); a 14 % increase in plasma-8-OHdG ([0 % to 31 %], p = 0.049); and a 45 % increase in urinary-8-OHdG ([3 % to 105 %], p = 0.03). Doubling particle number concentration (PNC) exposure was associated with a 22 % increase of plasma-8-OHdG at 3 h post exposure (p = 0.01). A 60-min exposure to TIG welding fume in a controlled, well-ventilated setting induced acute oxidative stress at 3 h post exposure in healthy, non-smoking apprentice welders not chronically exposed to welding fumes. As mass concentration of TIG welding fume particles is very low when compared to other types of welding, it is recommended that additional exposure metrics such as PNC are considered for occupational risk assessments. Our findings highlight the importance of increasing awareness of TIG welding fume toxicity, especially given the realities of welding workplaces that may lack ventilation; and beliefs among interviewed welders that TIG represents a cleaner and safer welding process.

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46 citations