Nanoscale phase separations in as-fabricated thick super duplex stainless steels

Hosseini, Vahid A.; Lindgren, Kristina; Thuvander, Mattias; Gonzalez, Daniel; Oliver, James; Karlsson, Leif

doi:10.1007/s10853-021-06056-0

Cited by 6 publications

(3 citation statements)

References 25 publications

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“…This understanding becomes particularly important for thick gauge sections of SDSS where it is not possible to cool the whole gauge thickness equally after solution treatment. In a recent study [17], it was shown that PS already occurs in the ferrite of asfabricated thick hot-rolled SDSS. This, therefore, raises the concern how the gauge thickness influences the PS during heat treatment and subsequent aging during service.…”

Section: Introductionmentioning

confidence: 96%

Effect of Cooling Rate after Solution Treatment on Subsequent Phase Separation Evolution in Super Duplex Stainless Steel 25Cr-7Ni (wt.%)

Liu

Das

King

et al. 2022

Metals

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The effect of cooling rate after solution treatment on the initial structure of super duplex stainless steel 25Cr-7Ni (wt.%), and the effect of the initial structure on phase separation (PS) evolution during subsequent aging were investigated. The nanostructure in the bulk of the steel was studied using small-angle neutron scattering (SANS). Ex situ SANS experiments showed that the rate of PS differs during aging, due to the different initial structures imposed by the difference in cooling rate after solution treatment. In situ SANS experiments revealed that the PS is already pronounced after aging at 475 °C for 180 min and that a slower cooling rate after solution treatment will lead to more significant PS. Hence, PS depends on the plate thickness, imposing different cooling rates in the production of duplex stainless steels.

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Section: Introductionmentioning

confidence: 96%

Effect of Cooling Rate after Solution Treatment on Subsequent Phase Separation Evolution in Super Duplex Stainless Steel 25Cr-7Ni (wt.%)

Liu

Das

King

et al. 2022

Metals

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“…However, some studies have shown that in highly alloyed DSS such as super duplex stainless steels (SDSS), nanostructure changes can be present already in as-received materials. [9,10] In samples with low Cu content, the main phenomenon was Fe and Cr phase separation, while in Cu-containing SDSS, CRPs were also present in the ferrite. Therefore, 475 °C-embrittlement in SDSS may happen during short aging times such as overheating, fire, long cooling after fabrication, etc.…”

Section: Introductionmentioning

confidence: 99%

Influence of Fabrication Route and Copper Content on Nature and Kinetics of 475 °C‐ Embrittlement in Cu‐Containing Super Duplex Stainless Steels

Hosseini,

Thuvander,

Lindgren

et al. 2023

steel research int.

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The influence of hot‐rolling, hot isostatic pressing (HIP), welding, as well as copper content on low temperature phase separations and 475 ˚C‐embrittlement was studied in copper‐containing super duplex stainless steels. To suppress the presence of any phase separations, the samples were solution annealed and quenched, and to study the kinetics and nature of phase transformations during fabrication, the samples were aged for a very short duration of 5 min at 475 ˚C. Atom probe tomography results of medium Cu aged samples revealed that the processes involving more plastic deformation such as hot rolling and HIP accelerated Cr and Fe phase separation and caused precipitation of Cu‐rich particles (CRPs) in the ferrite, resulting in significant toughness loss. In contrast, the weld did not show a high level of Fe and Cr phase separation or CRP precipitation, preserving its toughness after the short aging. The experiment and the inverse interdiffusion calculations revealed that raising the Cu content slowed down Fe and Cr phase separation but significantly increased the CRP number density and decreased the toughness of the HIPed material. Precipitation simulation of CPRs showed that the model must be modified based on each processing condition. We conclude that hot rolling and HIP accelerate 475 ˚C‐ embrittlement, which could not be prevented by raising the Cu content.This article is protected by copyright. All rights reserved.

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“…As the heat input during welding increases, it leads to abnormal grain growth within the weld. Additionally, a substantial amount of ferrite is generated, diminishing the microstructure and properties of the weld [4,[12][13][14][15]. Hence, activated-flux TIG welding (A-TIG) has emerged as a primary welding process for thick-walled structural parts made of 1Cr21Ni5Ti duplex stainless steel.…”

Section: Introductionmentioning

confidence: 99%

Improving Welding Penetration and Mechanical Properties via Activated-Flux Smearing by Tungsten Inert Gas Arc Welding

Yue,

Huang,

et al. 2023

Metals

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For the welding process of thick-walled structural components in liquid rocket engines, the activated-flux TIG method can effectively address issues such as the formation of intermetallic phases in the weld seams, thereby enhancing mechanical performance. The present study investigates the activated-flux TIG welding technique on 10mm thick 1Cr21Ni5Ti duplex stainless steel plates. Various activated-flux, including -SiO2, TiO2, V2O5, NiO, MnO2, CaO, AlCl3, CaF2, B2O3 Cr2O3, and Al2O3, were examined to understand their impact on the weld-bead geometry. The aim was to determine the optimal activator ratio for the effective welding of 1Cr21Ni5Ti duplex stainless steel. The weld-shift experiment confirmed that the deep penetration observed in flux-assisted welding is attributed to Marangoni convection in the molten pool. Comprehensive evaluations and analyses were performed on the microstructure and mechanical properties of the normal welded joint and the A-TIG welded joint. Finally, the study delves into a discussion on the factors influencing changes in the weld penetration, microstructure, and mechanical properties of the weld.

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Nanoscale phase separations in as-fabricated thick super duplex stainless steels

Cited by 6 publications

References 25 publications

Effect of Cooling Rate after Solution Treatment on Subsequent Phase Separation Evolution in Super Duplex Stainless Steel 25Cr-7Ni (wt.%)

Effect of Cooling Rate after Solution Treatment on Subsequent Phase Separation Evolution in Super Duplex Stainless Steel 25Cr-7Ni (wt.%)

Influence of Fabrication Route and Copper Content on Nature and Kinetics of 475 °C‐ Embrittlement in Cu‐Containing Super Duplex Stainless Steels

Improving Welding Penetration and Mechanical Properties via Activated-Flux Smearing by Tungsten Inert Gas Arc Welding

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