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Influence of Microalloying Elements (Ti, Nb) and Nitrogen Concentrations on Precipitation of Linepipe Steels - A Thermodynamic Approach
  • Sima Aminorroaya Yamini
Sima Aminorroaya Yamini
Sheffield Hallam University Faculty of Arts Computing Engineering and Sciences
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A CALculation of PHase Diagrams (CALPHAD) approach was used to study the formation temperatures of nitride and carbonitride precipitates in nominated linepipe steels. The calculated results were in good agreement with relevant experimental data reported in the literatures, where the optimum titanium to nitrogen ratio and austenite grain growth was studied in similar steel compositions. The niobium concentration up to 0.12 wt% showed no influence on the formation temperature of nitrides in a common linepipe steel composition, while significantly increased the precipitation temperature of niobium carbides up to 0.03 wt%. Nitride precipitates contained a high concentration of titanium while niobium contributed mostly to the formation of carbide/carbonitrides. Although the dissolution and growth of precipitates are controlled kinetically, the thermodynamic calculation approach can be used to efficiently predict the equilibrium amount and composition of the stable phases in chemically complex systems. This results in a more accurate design of experiments, to minimise the number of tests required to obtain optimum chemical compositions and heat treatment procedures.

Peer review status:Published

15 Jan 2020Submitted to Engineering Reports
20 Jan 2020Submission Checks Completed
20 Jan 2020Assigned to Editor
15 Feb 2020Editorial Decision: Reject Without Review & Resub
30 May 20201st Revision Received
01 Jun 2020Assigned to Editor
01 Jun 2020Submission Checks Completed
14 Jul 2020Reviewer(s) Assigned
10 Sep 2020Editorial Decision: Revise Major
04 Nov 20202nd Revision Received
04 Nov 2020Assigned to Editor
04 Nov 2020Submission Checks Completed
05 Nov 2020Editorial Decision: Accept
09 Dec 2020Published in Engineering Reports. 10.1002/eng2.12337