Review

Influence of slag composition on the cleanliness of electroslag ingot during low frequency electroslag remelting

School of Metallurgy Engineering, Anhui University of Technology, Ma’anshan 243002, P.R. China

^* e-mail: shixiaofang602@163.com

Received: 14 December 2024
Accepted: 5 March 2025

Abstract

Electroslag remelting (ESR) experiments were performed on 304L austenitic stainless steel using a laboratory-scale low-frequency electroslag furnace with Al₂O₃-CaO-CaF₂ and Al₂O₃-CeO₂-CaF₂ slags of varying compositions. The study aimed to evaluate the influence of slag composition on the oxygen and nitrogen content, as well as the number, size, and types of inclusions in ESR ingots under low-frequency power supply conditions. The results demonstrated that, under low-frequency conditions, increasing the CaO or CeO₂ content while decreasing Al₂O₃ in the slag significantly reduced the oxygen content in the ingots. Among the slag components, CaO exhibited a markedly stronger deoxidation effect than CeO₂ under identical conditions. Regardless of slag type, the nitrogen content in the ingots remained stable. In the Al₂O₃-CaO-CaF₂ system, higher CaO content decreased the number and size of inclusions and shifted their type from Al₂O₃ to aluminum-calcium composite inclusions. Similarly, in the Al₂O₃-CeO₂-CaF₂ system, a 15% CeO₂ content reduced the inclusion size and number, leading to the formation of cerium-containing composite inclusions. The micro-electrolysis of slag components under low-frequency power supply was identified as the primary mechanism influencing inclusion characteristics, with slag stability playing a pivotal role in determining inclusion distribution and number in the ingots. Consequently, careful slag composition selection is essential for optimizing low-frequency ESR processes.