IMPROVEMENTS ON RESISTANCE TO STRESS RELAXATION OF LOW CARBON MARTENSITE

ABSTRACT In order to improve the resistance to stress relaxation of low carbon martensite (LCM), five kinds of processes have been investigated. X-ray profile analysis was used to measure the microstress and subgrain size. Experiments show: Stress relaxation is a procedure in which microstress and subgrain size decrease step by step. Presetting, presetting+aging, thermal-presetting all decrease not only microstress but also subgrain size. LCM tempered at 340°C possesses the least microstress but slightly larger subgrain size in this study. The effects of each process on stress relaxation and micro-plastic deformation have been explored.