Optimization of Mold Powders for High‐Nitrogen Stainless Steel Based on Mold Thermocouple Temperature Variation

Abstract

High‐nitrogen stainless steel (HNSS) is prone to surface depression during continuous casting; however, its high‐temperature solidification characteristics and mold powder design have not been reported. Based on the analysis of mold thermocouple temperature variation, this study clarifies the high‐temperature solidification characteristics of HNSS and the cause of surface depression. It optimizes the mold powder for HNSS continuous casting according to factory and laboratory research. The factory trials indicate that the mold thermocouple temperature at the corresponding location decreases by 6.0–20.9 °C when the slab surface is depressed. The analysis shows that the high initial solidification strength of HNSS causes its slab surface depressions. Owing to this characteristic, the mold powder for HNSS should have a suitable melting rate, low basicity, and proper Al2O3. This low‐basicity Al2O3‐containing slag has a crystal slag film near the mold side and a thick liquid slag film near the slab. It can both provide good lubrication and control horizontal heat transfer.

Formation of nepheline in the heating process of mould fluxes and its effect on sintering behaviour

“…In the process of stainless-steel continuous casting, slag rims will cause slab surface depressions. 5 During the continuous casting process, the formation of the slag rim is related to the sintering behaviour of the mould flux, [6][7][8] which involves the phase reaction and the secondary phase precipitation behaviour during the heating process. [9][10][11] Therefore, it is significant for the future development of continuous casting to study the phase transformation behaviour of mould flux during the heating process and prevent the excessive growth of slag rim, which improves the smooth running of the continuous casting process and the slab quality.…”