Thermal and athermal contributions to the flow stress of martensite

Recent theories consider as-quenched martensite as a composite which strain hardens by the gradual yielding of constituents. An underlying hypothesis is that hardening comes primarily from athermal hardening contributions. In this contribution, we conducted strain-rate jump and tension-compression tests to quantify the athermal and kinematic hardening contributions in martensite. It is shown that athermal hardening accounts for ~75% of the total strength of as-quenched martensite. The magnitudes of athermal and kinematic hardening decrease as a function of tempering. A correlation between the athermal and kinematic hardening contributions is identified and shown to be independent of the chemistry and tempering conditions examined in this work.