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. © 2003 Elsevier Science B.V. All rights reserved.

Suresh Krishnamoorthy Seshadri

Composition

Corrosion resistance

Fillers

microstructure

Nickel

Stainless steel

Composition Control

Welds

corrosion

industrial application

mechanical property

Structural analysis

Welding

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Effect of weld metal chemistry and heat input on the structure and properties of duplex stainless steel welds

Materials Science and Engineering A

The joining of duplex stainless steel was attempted by electron beam and laser beam welding, introducing nickel and nitrogen into the weld metals by different means. The addition of nickel and nitrogen has a significant role on the microstructure, phase balance and impact toughness, but it seems to have no appreciable influence on hardness. © 2005 Elsevier B.V. All rights reserved.

Materials Letters

Effect of nickel and nitrogen addition on the microstructure and mechanical properties of power beam processed duplex stainless steel (UNS 31803) weld metals

The fillers ER80S-Ni3 and ER2553 were deployed to obtain 10 mm thick joints of super-duplex stainless steel (SDSS) and high strength low alloy (HSLA) steel using pulsed direct current (PDC) welding approach. Laths of martensite/bainite with retained austenite were observed in the weld seam microstructure of ER80S-Ni3 joints; whereas austeno-ferrite microstructure was seen in ER2553 joints. Considerable changes in the ferrite percentage was noticed in the fusion region of ER2553 joints. Repeated thermal cycles resulted in austenite reformation and thus a lower ferrite percentage was ascertained in the root pass of ER2553 joints. The tensile ruptures were occurred on the base metal region of HSLA for both the cases. Notch tensile studies demonstrated that the weld seams employing ER80SNi-3 filler imparted better strength and failure occurred in the base metal of HSLA. A decrease of 19 % and 76 % in the impact toughness was observed for ER2553 and ER80S-Ni3 joints when operated in room temperature (RT). The impact toughness of the weld seams was drastically deteriorated while operating at −196 °C, reasoned to the ductile to brittle transition. © 2019 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Microstructure and mechanical integrity relationship of PDC weld joints involving dissimilar marine grade alloys

The fusion zone microstructure and mechanical properties of UNS S32750 joints obtained from gas tungsten arc (GTA), gas metal arc (GMA) and flux cored arc (FCA) welding processes were investigated. The formation of grain boundary, Widmanstätten and intragranular austenite were observed in the fusion zone of the weldments. Electron back scattered diffraction (EBSD) analysis confirmed the presence of chi (ψ) and sigma (σ) phases in the reheated fusion zones of all the weldments. Tensile failures occurred at the fusion zone for all the weldments and the joint efficiency was found to be greater for GTA welds than the others. The number of welding passes and heat input had a significant impact on the ferrite: austenite ratio. FCA weldments experienced inferior notch toughness at both room temperature and sub-zero temperature owing to the prominent amount of secondary austenite and precipitation of intermetallic phases compared to the other weldments. © 2019 Elsevier B.V.

Journal of Materials Processing Technology

Multi-pass arc welding techniques of 12 mm thick super-duplex stainless steel

In the present study, the influence of microstructural changes on the mechanical and corrosion properties of the dissimilar weld between austenitic stainless steel (ASS 316L) and duplex stainless steel (DSS 2205) has been examined and reported. The weld joint was fabricated through the use of gas tungsten arc welding process with a nickel enhanced filler metal ER 2209. The microstructural changes observed in the fusion zone such as nucleation of delta ferrite (δ), austenite (γ) reformation, precipitation of intermetallic phases and the formation of coarser ferrite phases in the HAZ have been reported. Also, the mechanical properties of the weldment such as microhardness, impact toughness and tensile properties have been correlated with microstructural changes. Potentiodynamic polarization test results showed a better electrochemical behavior for ASS 316L than with the weldment and the parent metal of DSS 2205. The austenite phase was found to be electrochemically more stable than the ferrite phase in duplex microstructure. On the other hand, achievement of the stress corrosion cracking resistance by the weldment and the parent metal of DSS was found to be excellent, whereas ASS 316L ended with surface fissures. © 2018, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Investigation of Structure Property Relationship of the Dissimilar Weld Between Austenitic Stainless Steel 316L and Duplex Stainless Steel 2205

This article addresses the joining of 5 mm thick plates of marine grade, super-austenitic (AISI 904L) and super-duplex stainless steels (UNS S32750) by pulsed current gas tungsten arc welding using duplex and austenitic stainless steel fillers. Microstructure studies revealed the segregation of Mo-rich phases in the fusion zone while employing ERNiCrMo-10. Grain coarsening was observed at the heat affected zone (HAZ) of super-duplex stainless steel in both the cases. The study attested that all the tensile failures experienced in the parent metal, AISI 904L for both the weldments. Charpy V-notch impact studies demonstrated that the weldments employing ER2553 were experienced better impact toughness than ERNiCrMo-10 weldments. Further potentiodynamic polarization test in 3.5% NaCl environment was conducted on the coupons of the weldments. The coupons of the weldments were then tested for accelerated corrosion in salt fog chamber for 300 h in 3.5% NaCl environment. This accelerated corrosion test concludes that the parent metal AISI 904L experienced better corrosion resistance than the fusion zones. The investigation also deals with biocorrosion studies of the dissimilar welds of super-austenitic and super-duplex stainless steels. Microbial consortium comprising of six bacterial isolates of which four were Pseudomonas strains P. aeruginosa strain MB1, P. aeruginosa strain MB2, P. fluorescens and P. flavescens, two belonged to Bacillus strains, B. subtilis and B. cereus, for the first time. The bacterial isolates were inoculated in the medium with the presence of the metal coupons. The results were obtained after 15 and 30 days interval and compared with the control to determine the rate of biocorrosion which confirms that there is an accelerated deterioration of the metal coupons by the microbial strains. © 2017

Microstructure, mechanical properties and biocorrosion behavior of dissimilar welds of AISI 904L and UNS S32750

Duplex Stainless Steels

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Journal	Data powered by TypesetMaterials Science and Engineering A
Publisher	Data powered by TypesetElsevier BV
ISSN	09215093
Open Access	No