Effect of heat treatments on room temperature creep strain of a high strength steel

Under certain service conditions for some creep resistant metallic materials, creep at ambient temperature rather than high temperature is of concern. The room-temperature creep behavior of a high strength steel has been investigated for five heat treatment schedules. The primary creep behavior obeyed a logarithmic creep law and the creep mechanism was identified as pure dislocation creep. It is demonstrated that for steels of similar yield strength and the hardness after heat treatment, the creep strain was significantly lower in a steel quenched at 210 degrees C in molten salt for 600 minutes and then tempered. The decrease in creep strain is mainly attributed to the absence of ferrite, the refined precipitate distribution, together with the structural uniformity of the tempered martensite. The possible influence of dislocations on the creep strain is discussed.