Influence of heterogeneous mechanical properties on the performance of forward static bending test of rail welded joint

The contact FE model for forward static bending test of the rail joint welded by narrow gap arc welding (NGAW) was established, in which the welded joint with heterogeneous mechanical properties was divided into multiple regions with gradual and step-changed mechanical properties determined according to the hardness distribution characteristics of the actual rail welded joint. Then the stress and strain distribution of the heterogeneous rail welded joint was calculated and analyzed under the forward static bending load, referring to the standard of static bending test for the rail joint welded by flash butt welding. The calculated results indicate that the magnitude of equivalent stress (Von Mises stress) presents positive correlation with the value of strength in the rail welded joint, while the failure tendency presents negative correlation with the value of strength, and the lowest strength region in HAZ is the weakest and most vulnerable part of the rail welded joint. Therefore, increasing the strength of soften zone in HAZ by appropriate post-weld heat treatment process is effective to improve the performance of forward static bending test. Further analysis was made by adjusting the value of strength in the weld zone within the heterogeneous rail welded joint, and it was found that the weld zone with high strength match could reduce the value of Von Mises stress of all other zones and improve the performance of forward static bending test of the rail welded joint. All these researches are expected to provide valuable reference and guidance for the adjustment and optimization of the process of NGAW and post-weld heat treatment, and the improvement of the performance of static bending test of rail welded joint.