Effect of Melt Rate on Surface Quality and Solidification Structure of Mn18Cr18N Hollow Ingot during Electroslag Remelting Process

A new method for manufacturing Mn18Cr18N steel applied to retaining ring has been developed based on hollow ESR ingot. The ESR hollow ingot not only keep away from upsetting and punching, provide hollow billet for forging directly, but also meet the need of high quality of the raw material. ESR hollow ingot of Mn18Cr18N steel has been produced successfully in our lab. Melt rate is the most important technological parameter of electroslag remelting (ESR) process, which influences ingot quality and production efficiency. To further investigate the influence of surface quality on melt rate, the experimental results comparing to the simulations results have been implemented in this paper. A mathematical model to describe the temperature distribution and the solidification structure of ESR hollow ingot of Mn18Cr18N steel has been established. The change of metal pool profile, pool cylinder part height, and grain growth angles during hollow ESR process are calculated based on the coupled technology of CAFE method and the moving boundary method, which are consistent with the experimental results. The experiment of hollow ESR Mn18Cr18N steel at the most suitable melt rate obtained by numerical simulation results has been carried out to reveal the law of cylinder part height of metal pool changing with the withdrawal speed. The optimal technological parameters applied in the experiment of hollow ESR process can reasonably control the surface quality of Mn18Cr18N hollow ingot.