Study Of The Transition Mechanism Of Organization Structure And The Performance Of Rail Steel After Shot Peening

Rail plays an important role in our transportation system and is the main means of transport by land transport. The role of rail is essential in the rail transport system that it plays a supporting car-body, guiding role. It is an important factor affecting driving safety. With the rapid development of China’s high-speed rail construction, improvement and increase in speed axle, making rail service conditions worsened, leading to wear and fatigue broken rail ring phenomenon is more serious, so how to improve strength and fatigue broken rail loop the ability to become the focus of the railway workers.This test uses a modified GM centrifugal blasting machine for U71 Mn steel and U75 V steel common railway steel shot high energy experiments, and analyze the microstructure and microhardness of the U71 Mn steel with U75 V steel after shot peening and of the U71 Mn steel after shot peening with U71 Mn steel after running. Explore the organizational changes and strengthening mechanism of the U71 Mn steel with U75 V steel after shot peening and analyze the feasinility of peening applying in U71 Mn steel with U75 V steel. Using 1mm diameter projectile speed of 45 m / s, respectively, at different times of their shot peening process, and the surface roughness after shot, microstructure and hardness of the plastic deformation zone distribution analysis. The results show that: the U71 Mn rail steel after running have plastic deformation zone around 200μm thickness, surface micro-hardness value of about 410HV; surface roughness of the U71 Mn steel after shot peening is lower than 6.5μm, the hardened layer thickness and surface hardness values were shot with the increasing the extension of time, the thickness of the hardened layer after 180 min peening saturated, about 85μm, surface hardness values after 180 min shot peening about 430 HV, ferrite grains in the surface layer after peening 60 min refined to about 60 nm, and crack-free surface, the surface hardness of about 350HV; U75 V steel surface after peening ferrite grains are refined to about 120 min 60nm, the thickness of the plastic deformation reaches saturation peening after 180 min, about 75μm, at this time the surface microstructure hardness of about 430 HV, shot peening no cracks, surface hardness value of about 350 HV, cracks before 120 min after 60 min, tissue deformation mechanism similar U71 Mn steel.