Theoretical study of laminar plasma quenching of rail steel using the fluid-solid-thermal coupling method

Abstract

Laminar plasma quenching (LPQ) is an effective surface hardening method for improving the wear resistance of rails. Nonetheless, there has been very little systematic theoretical research on the mechanism of how rail materials are strengthened through LPQ. Therefore, based on the fluid-solid-thermal coupling method, a complete theoretical analysis model for LPQ of a U75V rail was established for this paper. The influence of the laminar plasma jet on the spatial distribution of the hardened layer was investigated, and the residual stress distribution on the rail surface during LPQ was reconstructed. The results show that the distribution of the hardened layer will significantly affect residual stress. As plasma flow rate increases, the width-depth ratio of the hardened layer first decreases and then increases. This research is of great significance for understanding the mechanism of rail plasma quenching, and for the application of fluid-solid- thermal coupled methods.