高碳马氏体不锈钢8 Cr13 MoV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M23 C6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、M7 C3型和M23 C6型碳化物,由于偏析导致最终组织中碳化物以M7 C3型为主,少量M23 C6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 8 Cr13 MoV

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 M23 C6 under the equalized solidification condition, while ferrite, martensite, retained austenite, M7 C3 and M23 C6 in the practical solidification condition. The main carbides are M7 C3 , and a small number of M23 C6 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 .