Effect of surface nanocrystallization on fatigue behavior of 35# carbon steel

摘要

A nanostructured surface layer was formed on 35# carbon steel by means of surface ultrasonic impact peening (SUIP).The microstructure of the peened surface layer was characterized by using transmission electron microscopy (TEM). Mi-crohardness distribution along the depth from the peened surface layer was measured,and residual stress in the topmost surface was measured at the same time. Fatigue behavior of the carbon steel subjected to the SUIP process was investi-gated. A nanostructured layer with average grains size of 12.7nm was formed,of which microhardness is higher than twice of that in matrix and residual compressive stress can reach -366MPa. The SUIP process has improved the fatigue strength as much as 15% for the carbon steel based on fatigue life 5×106 cycles.