Fatigue Crack Propagation in U75V Rail Base and Welded Materials

This study integrates experimental and numerical methods to investigate the fatigue crack propagation behavior of U75V, a high‐carbon vanadium microalloyed steel commonly used in Chinese railway applications. Room‐temperature crack propagation tests are conducted on 8 CT specimens, where the a ‐ N curves of welded and base materials are achieved for obtaining the Paris formula parameters C and m . Experimental results show that the crack propagation rate of base material is , and it is for the welded one. Additionally, numerical simulations are performed by the ABAQUS/FRANC3D software to characterize the wheel–rail interaction, where the rail stress field and the subcrack propagation are achieved. It indicates that the base rail exhibits a maximum stress of 501 MPa, while the welded material reaches 488 MPa, with both peaks occurring 3.5 mm below the rail surface. Under the same cyclic load, the maximum initial stress intensity factor of the welded material is lower than that of the base material, and the crack propagation rate of the welding material is faster, while the crack propagation angle of the base material is larger. This study provides accurate experiment parameters for U75V rails and also proposes a numerical method for fatigue life assessment potentially applicable in similar steel structures.