高碳马氏体不锈钢8Cr13MoV钢铸态组织及碳化物

利用Thermo-Calc软件对8Cr13MoV马氏体不锈钢的凝固过程进行计算,利用光学显微镜、扫描电子显微镜和X射线衍射分析仪对铸态组织和碳化物形貌以及类型进行观察与分析,利用Gleeble热模拟试验机测定材料的静态连续冷却转变曲线.结果表明,8Cr13MoV在平衡凝固条件下组织为铁素体和M₂₃C₆型碳化物,而在实际的凝固条件下,组织为铁素体、马氏体、残余奥氏体、M₇C₃型和M₂₃C₆型碳化物,由于偏析导致最终组织中碳化物以M₇C₃型为主,少量M₂₃C₆以薄片或树枝状分布在晶界上.由于较高的C和Cr含量,以0.1℃·s^-1的冷却速率冷却时,奥氏体也会发生马氏体转变.

Microstructure and carbides of as-cast high carbon martensitic stainless steel 8Cr13MoV

The solidification process of 8Cr13MoV martensitic stainless steel was calculated by using Thermo-Calc software. The solidification microstructure, morphology and type of carbides were analyzed by optical microscopy, scanning electron microscopy and X-ray diffraction. The static continuous cooling transformation curve was measured by Gleeble thermal simulator. The results indicate that the microstructure of 8Cr13MoV includes ferrite and M₂₃C₆ under the equalized solidification condition, while ferrite, martensite, retained austenite, M₇C₃ and M₂₃C₆ in the practical solidification condition. The main carbides are M₇C₃, and a small number of M₂₃C₆ with lamellar or dendritic morphology distribute on the grain boundaries, which can be attributed to element segregation. Because of high C and Cr contents, austenite can transform to martensite at a cooling rate of 0.1℃·s-1.