Effect of weld metal chemistry and heat input on the structure and properties of duplex stainless steel welds
15 Oct 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing (Elsevier)-Vol. 358, Iss: 1, pp 9-16
TL;DR: In this article, a low heat input process viz., EBW and another commonly employed process, gas tungsten-arc welding have been employed for welding of duplex stainless steels with and without nickel enhancement.
Abstract: The excellent combination of strength and corrosion resistance in duplex stainless steels (DSS) is due to their strict composition control and microstructural balance. The ferrite–austenite ratio is often upset in DSS weld metals owing to the rapid cooling rates associated with welding. To achieve the desired ferrite–austenite balance and hence properties, either the weld metal composition and/or the heat input is controlled. In the current work, a low heat input process viz., EBW and another commonly employed process, gas tungsten-arc welding have been employed for welding of DSS with and without nickel enhancement. Results show that (i) chemical composition has got a greater influence on the ferrite–austenite ratio than the cooling rate, (ii) and even EBW which is considered an immature process in welding of DSS, can be employed provided means of filler addition could be devised.
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TL;DR: In this paper, the influence of the use of restrain in welding, especially in balancing phase, microstructure and microhardness has been observed, in a duplex stainless steel UNS S31803.
Abstract: Duplex stainless steels present ferrite and austenite in their microstructure in order to join good mechanical properties and corrosion resistance. These materials are very used in petrochemical industry, being the DSS UNS S31803 one of the most commercially known. There were not much published literature to study the influence of the precipitation of Widmanstatten austenite in joins with some restriction. This work has as objective to analyze the influence of the restriction in the phase balance of austenite and ferrite, in the morphology of the austenite, in the microhardness and the toughness of both HAZ and FZ. Shielded electrode AWS E2209-17 was used to weld V joints in the duplex stainless steel UNS S31803. Welding has been performed in two levels of energy C1 (15 kJ/cm) and C2 (20 kJ/cm), with and without restriction. In a generalized manner, it was observed a greater amount of ferrite in the finishing passes when compared to the first passes. Bigger amounts of Widmanstatten austenite in the conditions welded with restriction had been observed. Generally, the HAZ presented a coarser microstructure in the finishing passes, in way that did not show significant differences when compared with the conditions with and without restriction. Microhardness level was lower when large amount of Widmanstatten has been presented. Differences in energy absorbed in HAZ and FZ has not been observed when comparing conditions with and without restriction. The influence of the use of restraint in welding, especially in balancing phase, microstructure and microhardness has been observed.
3 citations
Cites background from "Effect of weld metal chemistry and ..."
...[4] Muthupandi, V....
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...Além disso, outras razões podem estar relacionadas, como: tensões residuais, dureza, tamanho de grão e esferoidização de partículas de austenita intragranular, além de formação de fases fragilizantes [4]....
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...É primordial a obtenção do balanço microestrutural de 50% austenita e 50% ferrita para aliar boa resistência mecânica e resistência à corrosão [4]....
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TL;DR: In this article, the effect of a monel/nickel interlayer electrode prepared with a thickness of 2 mm on the weldability properties of duplex stainless steel plates welded by means of plasma transfer arc welding was investigated.
Abstract: The aim of this study is to investigate the effect of a monel/nickel interlayer electrode prepared with a thickness of 2 mm on the weldability properties of duplex stainless steel plates welded by means of plasma transfer arc welding. After welding, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometry were carried out to determine the microstructural changes that occurred in the interface regions of the welds. Moreover, tensile strength, microhardness and fractography tests were conducted for assessing the mechanical properties of the welded specimens. The results of tests and examinations indicated that the tensile strength of welded parts with a nickel interlayer was higher than that of with and without a monel interlayer.
3 citations
10 Jan 2020
TL;DR: In this paper, post weld thermal aging of DSS (duplex stainless steel) welds resulted into complex precipitation that comprised of intermetallic carbides, oxides and sigma-phase in different zones of the welds.
Abstract: Post weld thermal aging of DSS (duplex stainless steel) welds resulted into complex precipitation that comprised of intermetallic carbides, oxides and sigma-phase in different zones of the welds. Maximum ferrite dissolution was observed in the weld metal followed by the HAZ (heat affected zone) and the base metal. Sigma phase precipitated preferentially along γ/δ (austenite/ferrite) interfaces besides the formation of secondary austenite (γ2). Precipitated joints showed an increase in microhardness and yield strength, whereas their UTS (ultimate tensile strength) did not alter much. Aging resulted into a significant loss of tensile ductility (percentage elongation) which showed a degradation of 15.27% and 62.46% for the base metal and the weld metal respectively. The base metal's impact toughness did not show any appreciable loss, but a severe degradation of around 96% occurred in the impact toughness of the aged weld metal. Fatigue crack growth behavior showed that weld metal possessed superior fatigue strength than the base metal, which upon aging reduced drastically to 48.24 % and 28.44 % respectively. Pitting corrosion studies showed that weld metal exhibited superior pitting resistance than the base metal, and both of them suffered a loss of pitting resistance due to precipitation.
3 citations
01 Jan 2013
TL;DR: In this article, the effects of a single LSP impact on the nano-hardness, elastic modulus, residual stress, and phase transformation of AISI 304 SS joint are discussed.
Abstract: This chapter presents the effects of a single LSP impact on the nano-hardness, elastic modulus, residual stress, and phase transformation of AISI 304 SS. Further studies of different LSP paths on the mechanical properties and fracture morphology of the laser welded AISI 304 SS joint are presented and discussed.
2 citations
TL;DR: In this paper, axial external electromagnetic fields (EEMF) of 0 and 3 mT were applied during welding process to improve the resistance to localized corrosion in comparison with 0 mT. The resistance to crack initiation and fracture toughness were also improved with the application of the 3mT EEMF due to the modification of microstructural evolution during the thermal cycle involved in the welding process.
Abstract: During the welding process, Electromagnetic Interaction of Low Intensity (EMILI) was induced by applying axial External Electromagnetic Fields (EEMF) of 0 and 3 mT. Resistance to nucleation and growth of fatigue cracks was evaluated in Low Cycle Fatigue (LCF) regime to observe the short crack behaviour in a Fatigue Corrosion Test. The 3 mT EMILI was found to improve the resistance to localized corrosion in comparison with 0 mT. The resistance to crack initiation and fracture toughness were also improved with the application of the 3 mT EEMF due to the modification of the microstructural evolution during the thermal cycle involved in the welding process.
2 citations
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Book•
01 Jan 1997
TL;DR: In this paper, the authors present a non-destructive testing of welds for service experience, based on the application of service experience in metallurgy and metallurgical applications.
Abstract: Developments, grades and specifications Alloy design Microstructure Forming and machining Physical and mechanical properties Corrosion Stress corrosion cracking Welding metallurgy Welding processes Weld properties Non-destructive testing of welds Applications Service experience.
449 citations