Abstract:  The solidification test of 60Cr13 martensitic stainless steel was carried out by laser confocal microscope at the cooling rate of 5-60 ℃/min， and the secondary dendrite spacing and carbide precipitation morphology were observed by metallographic microscope， the area ratio of eutectic letensite was measured by image processing software. The results show that different from the thermodynamic equilibrium state calculated by Thermo-Calc， no ferritic phase is found to precipitate in the liquid phase during the solidification process， and then the peritectic reaction between the ferrite phase and the liquid phase form austenite phase. Instead， the austenite phase is precipitated directly from the liquid phase， and the rich solute liquid phase is excreted as the austenite gradually grew. Eutectic transformation occurs in the rich solute liquid phase to form Letenite. The secondary dendrite spacing is related to the cooling rate by y=402x^-0.58 . In addition， with the increase of cooling rate， the size and quantity of eutectic letenite decrease gradually， and the overall area proportion decreases gradually.

Key words: 60Cr13, Martensitic stainless steel, Cooling rate, Microstructure

摘要： 采用激光共聚焦显微镜对60Cr13马氏体不锈钢进行冷却速率为5～60 ℃/min的凝固试验，并使用金相显微镜对二次枝晶间距、碳化物析出形态进行观察，采用图像处理软件对共晶莱氏体的面积比进行测量。结果表明，与Thermo-Calc计算的热力学平衡状态不同，凝固过程中并未发现液相中析出铁素体相及随后铁素体相与液相形成奥氏体相的包晶反应，而是直接从液相析出奥氏体相，在奥氏体逐渐长大的同时排出富溶质液相，在凝固未期，富溶质液相发生共晶转变，形成莱氏体；二次枝晶间距与冷却速率存在y=402x^-0.58关系。另外，随冷却速率的提高，共晶莱氏体的尺寸逐渐减小，数量逐渐增加，整体面积占比逐渐减小。

关键词: 60Cr13, 马氏体不锈钢, 冷却速率, 组织