File(s) under embargo

Reason: Publisher requirement.

5

month(s)

16

day(s)

until file(s) become available

Microstructural characterisation of creep tested advanced austenitic stainless steel super 304H

journal contribution
posted on 07.03.2022, 14:43 authored by Charlotte PulsfordCharlotte Pulsford, Mark JepsonMark Jepson, Rachel ThomsonRachel Thomson, Tapasvi Lolla, John Siefert, N Komai, K Hashimoto, K Tominaga
Super 304H is an advanced austenitic stainless steel that is used as superheater and reheater tubes in power plants. The presence of second phases such as MX particles, M23C6, Cu particles and sigma phase that evolve during creep testing and during service expose can have an impact on the creep rupture properties and lifetime of these components manufactured from Super 304H. In this research, the phases present in the gauge section of two creep rupture samples of Super 304H that had been exposed to a uniaxial creep test at temperatures of 650°C (Sample B) and 700°C (Sample A) and stresses of 120MPa and 75MPa respectively, have been identified and quantified. These two creep samples had exhibited low creep ductility. Within the two creep samples, six phases have been identified: MX (Nb rich), sigma, Cu rich, M23C6 (Cr rich), modified Z phase and Fe (BCC). Quantification of Nb rich and Cu rich particles revealed approximately 10% more Nb rich and 16% more Cu rich particles in Sample A compared to Sample B. Furthermore, the average particle size measured in Samples A and B are similar for both the Nb and Cu rich particles. This shows that differing temperatures and stresses of the two creep tests did not have a significant impact on the presence, number or size of Nb and Cu rich particles in these samples. The amount of sigma phase measured in Sample A and Sample B was similar and lower than that predicted by thermodynamic calculations. However, there appears to be an association between the sigma phase and creep cavities as shown in 2D microstructural characterisation. The association of sigma and creep cavities could have contributed to the low creep ductility exhibited by these two creep samples.

Funding

EPSRC Centre for Doctoral Training in Carbon Capture and Storage and Cleaner Fossil Energy

Engineering and Physical Sciences Research Council

Find out more...

Mitsubishi Heavy Industries and Mitsubishi Power

Electric Power Research Institute

Underpinning Multi-User Equipment

Engineering and Physical Sciences Research Council

Find out more...

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

Materials at High Temperatures

Publisher

Taylor & Francis

Version

AM (Accepted Manuscript)

Rights holder

© Taylor & Francis

Publisher statement

This is an Accepted Manuscript of an article published by Taylor & Francis in Materials at High Temperatures on 17 Mar 2022, available online: http://www.tandfonline.com/10.1080/09603409.2022.2037328.

Acceptance date

28/01/2022

Publication date

2022-03-17

Copyright date

2022

ISSN

0960-3409

eISSN

1878-6413

Language

en

Depositor

Dr Mark Jepson. Deposit date: 7 March 2022