Effect of Tempering Process on Residual Stress in Hot Rolled Low Carbon Martensite High-Strength Steel Strip

Distribution of residual stress in hot rolled low carbon martensite high-strength steel strip was measured by means of blind-hole method in the steel before and after tempering. The hot rolled low carbon martensite high-strength steel strip was tempered at 450 degrees C, 500 degrees C, 550 degrees C or 600 degrees C. Before tempering, the value of the residual stress along the width direction is maximum at the edge, intermediate at the center, minimum at the 1/4 of the strip. The figure of the residual stress distribution along the width direction is like the shape of the letter "M". Residual stress of the strip is reduced after tempering. When tempering at 450 degrees C or 500 degrees C, evolution of residual stress is caused by changes of thermal stress. Distribution of residual stress becomes gentle. With tempering temperature increasing, distribution of residual stress is reversed, because evolution of thermal stress and phase transition stress changes in different time.