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The microstructural development of type 321 Austenitic Stainless Steel with long term ageing

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conference contribution
posted on 22.03.2016 by Rebecca Higginson, Graham Green, Simon Hogg, Sarah Spindler, Christopher Hamm
Austenitic stainless steel is important in the power generation industry where it is expected to be in service at high temperatures for extended periods of time. Work carried out on the microstructural development of two 321 stainless steel samples has shown that there are complex phase changes that can take place in this alloy. Although the alloy is expected to be fully austenitic at room temperature there is a fraction of ferrite present in the as-received materials. High temperature XRD has shown that this ferrite phase can be dissolved at temperatures between 800 and 900°C but precipitates on cooling at temperatures below 200°C. Due to the low temperature of formation, similarities in chemistry and orientations relationships indicate that the ferrite is forming in a displacive manor from the austenite grains. Thermal ageing at 750°C has been carried out up to times of 15,000 hours and the microstructural changes quantified. The fraction of sigma phase and ferrite increases with ageing time with a corresponding decrease in austenite fraction. This change in the microstructure is postulated to be caused by the changes in the matrix chemistry due to the formation of second phases particles.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

8th Stainless Steel and Duplex Steel Conference and Exhibition

Volume

1

Issue

1

Pages

581 - 590 (10)

Citation

HIGGINSON, R.L. ...et al., 2015. The microstructural development of type 321 Austenitic Stainless Steel with long term ageing. Presented at the 8th Stainless Steel and Duplex Steel Conference and Exhibition, Graz, Austria, 28-30th. April, pp. 581 - 590. (10)

Publisher

ASMET

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

31/01/2015

Publication date

2015

Notes

This is a conference paper.

Language

en

Location

Graz, Austria

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