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The influence of weld thermal cycle simulations on the microstructure of VM12-SHC steel

conference contribution
posted on 18.07.2019, 10:44 by Robert ByrneRobert Byrne, Mark JepsonMark Jepson, Rachel ThomsonRachel Thomson, J. Shingledecker, John A. Siefert
For VM12-SHC 11-12 wt. % Cr steel, there have been no systematic investigations to define the regions or characterise the microstructures within the heat-affected zone (HAZ) of weldments. In similar steels, these regions relate to the Ac1 and Ac3 transformation temperatures and can affect weldment performance. In this study, controlled thermal cycles were applied to VM12-SHC parent metal using a dilatometer and the Ac1 and Ac3 temperatures were measured for various heating rates. The Ae1 and Ae3 temperatures were also calculated by thermodynamic equilibrium modeling. Through dilatometry, thermal cycles were then applied to simulate the microstructures of the classically defined HAZ regions. The microstructural properties of each simulated material were investigated using advanced electron microscopy techniques and micro-hardness testing. It was found that the simulated HAZ regions could be classified as; (1) the completely transformed (CT) region, with complete dissolution of pre-existing precipitates and complete reaustenitisation; (2) the partially transformed (PT) region, exhibiting co-existing original martensite with nucleating austenite microstructures with partial dissolution of precipitates; and (3) the over tempered (OT) region, with no phase transformation but precipitate coarsening and decreased hardness.

Funding

We thank the Engineering and Physical Sciences Research Council (EPSRC) Centre for Doctoral Training in Carbon Capture and Storage and Cleaner Fossil Energy (grant number: EP/L016362/1) for their support of the project.

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Materials

Published in

Joint EPRI-123HiMAT International Conference on Advances in High Temperature Materials

Citation

BYRNE, R.G. ... et al., 2019. The influence of weld thermal cycle simulations on the microstructure of VM12-SHC steel. Presented at the Joint EPRI-123HiMAT International Conference on Advances in High Temperature Materials, Nagasaki, Japan, 21-25th October.

Publisher

© Electric Power Research Institute (EPRI)

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

16/07/2019

Publication date

2019

Notes

This paper is in closed access.

Language

en

Location

Nagasaki, Japan

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