The half-width values of X-ray diffraction profile and
microhardness on the electro-polished and ground surfaces of super
high strength steel 37SiMnCrNiMoV and spring steel 60Si2Mn that were quenched and tempered at different temperature were measured. At the same time, the
subgrain size and microstrain were calculated using X-ray diffraction profile analysis method. The results indicate that the higher the tempering temperature, the lower the half-width values and hardness on the electro-polished surface of two kinds of steel. Compared with that of electro-polished surface, the subgrain size on the ground surfaces of specimens tempered at higher temperature decreases, and the microstrain on these surfaces increases. As a result, the half-width values and
microhardness of the ground surfaces increase, which illustrate that the ground surfaces are work hardened. However, when the tempering temperature is lower, grinding decreases not only the subgrain size but also microstrain of the specimen surfaces. These changes of microstructure make microhardness increased and half-width values decreased. Otherwise, the yield strength on the ground surface of steel 37SiMnCrNiMoV tempered at 200℃ increases by 400MPa. The increase of the microhardness and yield strength demonstrates the ground surfaces of the specimens tempered at lower temperature are work hardened, too. It is obvious that the decrease of the microstrain and half-width values are abnormal. The mechanism of the abnormal decrease is discussed.