Influence of W and Ta content on microstructural characteristics in heat treated 9Cr-reduced activation ferritic/martensitic steels

• Published in: Materials characterization 2013-10, Vol.84, p.196-204
• Main Authors: Ravikirana, Mythili, R., Raju, S., Saroja, S., Jayakumar, T., Rajendrakumar, E.
• Format: Article
• Language: English
• Subjects: Carbides; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Martensite; Materials science; Microstructure; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; RAFM steel; Solidification; Tempering
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2013.08.003

This study aims at understanding the microstructural changes due to variation of W and Ta content and heat treatment in 9Cr–W–Ta–0.2V–C reduced activation ferritic/martensitic steels, with W and Ta concentrations varied from 1 to 2wt.% and 0.06 to 0.14wt.% respectively. An increase in concentration of W and Ta in the steels refined prior austenite grain size and lath width, though the change was not significant beyond 1.4 wt% W. Increase in W and Ta concentrations also resulted in a decrease in size and increase in number density of carbides on tempering. Microchemical analysis of M23C6 precipitates in tempered steel showed enrichment of W with increase in W content of the steel, whereas addition of Ta showed no significant change in chemistry of M23C6 or MX, but only increased the number density of fine MX precipitates. •W refines the prior austenite grains and lath width, while Ta refines only PAG size.•Addition of W increases the solubility of W in M23C6 and controls its coarsening.•Number density of M23C6 and MX increases with W and Ta content respectively.•Addition of W and Ta accelerates recovery of martensite due to finer substructure.