Effect of Prestrain and Tempering on the Residual Stress of Low-Carbon Microalloyed Steel

In this article a method that combines prestrain with tempering (PST) is used to study the effect of a thermomechanical treatment on the residual stress of high-strength steel and its underlying controlling mechanisms. The study results show that prestrain changes the material's dislocation distribution and carbide precipitation pattern and lowers the temperature controlling the residual stress. Compared with direct tempering (DT), 10% PST causes the temperature controlling the surface residual stress to decrease from 300 to 100 degrees C, reducing the surface residual stress by 76.2%. The temperature controlling the elastic strain energy decreases from 600 to 450 degrees C, and the elastic strain energy decreases by 75.2%. PST's action in controlling the residual stress involves two mechanisms. From room temperature to 300 degrees C, the residual stress is controlled by the precipitation plasticity generated by cementite precipitation, and the effect is mainly focused on controlling the surface residual stress. For temperatures of 300 degrees C and higher, the residual stress is controlled by precipitation-induced creep caused by carbide precipitation, and the effect is mainly focused on decreasing the elastic strain energy.