Non-instantaneous growth characteristics of martensitic transformation in high Cr ferritic creep-resistant steel

Abstract

Microstructural observation and high-resolution dilatometry were employed to investigate kinetics of martensitic transformation in high Cr ferritic creep-resistant steel upon different quenching/cooling rates. By incorporating the classical athermal nucleation and impingement correction, a non-instantaneous growth model for martensitic transformation has been developed. The developed model describes austenite/martensite interface mobility during martensite growth. The growth rate of martensite is found to be varied from 1 9 10 -6 to 3 9 10 -6 m/s. The low interface mobility suggests that it is not appropriate to presume the instantaneous growth behavior of martensite. Moreover, based on the proposed model, nucleation rate of martensite under different cooling rates is found to be nearly the same, while the growth rate of martensite is promoted by increasing the cooling rate.

Precipitates and Particles Coarsening of 9Cr–1.7W–0.4Mo–Co Ferritic Heat-Resistant Steel after Isothermal Aging

“…9~12wt.% Cr ferritic creep steels, as the key materials increasing the thermal efficiency of steam power plants, are widely used in power industries due to its excellent high temperature stability, high creep strength and stress corrosion cracking 1 – 4 . The excellent properties have been achieved through apparently minor compositional changes to well established steels like P91, P92 and P122 5 , 6 .…”