Thermal stability of ultrafine grained Fe-Cr-Ni alloy

Abstract

Equal channel angular pressing was used to refine the microstructure of a Fe-14Cr-16Ni (wt.%) alloy. The as-processed alloy had predominantly equiaxed austenite fine grains with an average grain size of 0.4. μm and a low fraction of deformation induced martensite. Ex situ isothermal annealing experiments showed the fine microstructure was thermally stable up to 673. K, and abnormal grain growth occurred at ~873. K. In situ annealing studies in a transmission electron microscope revealed the coarsening of grains. Analysis of grain growth kinetics from 873 to 1073. K yielded average activation energy of grain growth to be ~207. kJ/mol. The grain growth mechanisms and annealing induced evolution of mechanical properties were discussed. © 2012 Elsevier B.V..