Stress relaxation behavior of heat treated Inconel 718

Abstract

The stress relaxation of heat treated nickel-based superalloy, Inconel 718 at 1% strain and high temperature was investigated. Solution treatment was applied on the as-received material at 980°C for 1 h before water quenched followed by double aging treatments at 720 and 621°C for 8 h, respectively and then cooled in air. There are basically, two stages involved in stress relaxation namely transformation-controlled at the beginning of test and creep-controlled at later stage. Different temperatures show that two stages are present. This study has found that recovery process at grain boundary decreased Vickers micro-hardness and dislocation density due to prolonged relaxation time and further decreasing by increasing temperature. © 2012 Asian Network for Scientific Information.