Abstract: In the process of producing 1Cr13 stainless steel， serious longitudinal cracks breakout and transverse dents appear in the casting billet. FactSage8.2 thermodynamic software was used to calculate ternary and quadruple phase diagrams to design the ingredient of the protective slag. At the same time， the solidification characteristics of 1Cr13 stainless steel were calculated. As this steel is a peritectic steel， it will produce a sharp volume contraction during the solidification process， resulting in longitudinal cracks in the weak part of the blank shell. In order to avoid the dents and longitudinal crack caused by the uneven raw shell， the basicity of the protective slag should be improved， the crystallization property of the protective slag should be improved， and the heat transfer control ability of the protective slag should be improved too.The basicity of the new protective slag is 1.5， the slag is 6%MgO， 2%Li₂O， 16%Al₂O₃， 8%Na₂O， 3%B₂O₃， 10%CaF₂. The melting point of the original slag of 1Cr13 stainless steel is 1155 ℃， the constant temperature viscosity is 0.442 Pa·s， and the transition temperature is 1140 ℃. The melting point of the new protective slag is 1120 ℃， the viscosity is 0.304 Pa·s， the transition temperature is 1171 ℃， and the crystallization temperature is 1270 ℃. After actual production， the surface quality of the casting billet is obviously improved.

Key words: Longitudinal Crack, Transverse Depression, 1Cr13 Stainless Steel, Protective Slag, Viscosity

摘要： 在生产1Cr13不锈钢的过程中，铸坯出现了严重的纵裂漏钢及横向凹陷。利用FactSage8.2热力学软件计算三元以及四元相图对保护渣成分进行设计，同时，计算1Cr13不锈钢的凝固特性，由于该钢属于包晶钢，在凝固过程中会产生急剧的体积收缩，从而在坯壳薄弱处产生纵裂。为了避免初生坯壳不均匀引起的凹陷和纵裂，应适当提高保护渣碱度、改善保护渣结晶性能，并提升保护渣控制传热能力。新型保护渣碱度为1.5，渣中w［MgO］为6%，w［Li₂O］为2%，w［Al₂O₃］为16%，w［Na₂O］为8%，w［B₂O₃］为3%，w［CaF₂］为10%。1Cr13不锈钢原渣熔点为1155 ℃，定温黏度为0.442 Pa·s、转折温度1140 ℃，新型保护渣熔点为1120 ℃，黏度为0.304 Pa·s，转折温度为1171 ℃，结晶温度为1270 ℃。实际生产后，铸坯表面质量明显改善。

关键词: 纵向裂纹, 横向凹陷, 1Cr13不锈钢, 保护渣, 黏度