Numerical Investigation on the Electroslag Remelting of High Carbon Martensitic Stainless Steels

Abstract

Control of solidification structure and segregation is crucial to improve the service performance of high carbon martensitic stainless steels. Design of the electroslag remelting (ESR) process based on the essential parameters of melting rate, filling ratio, and slag thickness is a precondition to achieve optimal control of solidification structure and segregation of the steels. However, there is still a lack of coupled works giving deep insight into the overall effect of the parameters on the expected control. With this background, a 2D numerical model was established to probe into the effect of process parameters. The results showed that: (1) With the increase of melting rate from 90 kg/h to 180 kg/h, the molten metal pool depth increased by about 4 cm. Meanwhile, the center LST, PDAS, and SDAS increased by about 450 s, 100 μm, and 12 μm. The segregation index of C and Cr increased by about 0.15 and 0.09. (2) As the filling ratio increased from 0.16 to 0.43, the depth of the metal pool decreased by about 4.5 cm, LST and SDAS received a slight increase of about 41 s and less than 5 μm, but PDAS had little change. The segregation index of C had an increase of about 0.03, but the segregation index of Cr demonstrated tiny changes. (3) As the slag thickness increased from 0.08 to 0.14 m, the metal pool depth presented a first increase of about 1 cm and then a slight decrease. The center LST, PDAS, and SDAS first increased by 148 s, 30 μm, and 4 μm and then decreased slightly. The changes of the segregation index of C and Cr presented a similar tendency than that of LST, but the changes are extremely small. (4) A low melting rate less than 120 kg/h, a filling ratio of about 0.23–0.33, and a slag thickness of 0.08–0.10 m were appropriate to obtain good performance for ESR of high carbon stainless steels in this study.