Study on the Influence of Prior Cold Work on Precipitation Behavior of 304HCu Stainless Steel During Isothermal Aging

The precipitation strengthening behavior of 304HCu austenitic stainless steel during isothermal aging at 650 degrees C is studied under 10 and 20 pct prior cold-worked conditions. The age hardening behavior under these cold-working conditions have been studied using hardness and electrical conductivity measurements. The analysis of electrical conductivity and hardness variation, during isothermal aging at 650 degrees C using the Johnson-Mehl-Avrami equation, indicates an increase in precipitation kinetics in the matrix, influenced by the dislocations formed during cold working. Further, XRD profiles of different cold-worked samples obtained from the INDUS-2 synchrotron are able to indicate the formation of very fine precipitates during thermal aging and these findings are corroborated with conductivity and hardness changes. The observed change in precipitation kinetics due to deformation is analyzed to evaluate an equivalent change in activation energy which is attributed to an equivalent of increase in aging temperature. (C) The Minerals, Metals & Materials Society and ASM International 2019