喷射成形及时效处理对Cr_(12)MoV钢组织及性能的影响

Effect of Spray Forming and Aging Treatment on Cr_(12)MoV Steel

采用喷射成形技术制备了 Cr12 Mo V钢 ,应用金相、X射线衍射分析、差热分析等实验手段对该钢的微观组织及性能进行了分析和研究 .结果表明 ,喷射成形 Cr12 Mo V钢的显微组织得到了显著的细化 ,与 Cr12 Mo V钢铸态组织不同处在于其主要由奥氏体组成 .由于喷射成形过程中的冷却速度快 ,奥氏体中高度固溶了碳及合金元素 ,其晶格常数达 0 .362 0 nm,且喷射成形钢的马氏体起始转变温度 (Ms)亦低于常规工艺制备的钢的 Ms.随着时效温度的升高 ,亚稳奥氏体逐渐发生了转变 ,Cr12 Mo V钢的硬度在 570°C时效温度处出现峰值 ,由时效处理前的 HRC38增大至 HRC60 .时效合金主要由马氏体构成 .当时效温度高于 570°C时 ,Cr12 Mo V钢的硬度剧烈下降 .因此 ,570°C是喷射成形 Cr12 Mo V钢进行时效处理的临界温度 .

Cr 12 MoV steel was chosen as the spray formed material. Microstructure and property of the as sprayed steel were investigated by the optical metallography, X ray diffraction analysis, difference thermal analysis etc.. The results show that the as sprayed steel shows a considerate refinement of microstructure. Different from the as cast Cr 12 MoV steel, the as sprayed steel mainly consists of a highly supersaturated austenite due to the high solidification rate. The lattice parameter of austenite is 0.362 0 nm. The martensite start temperature of the as sprayed steel is lower than that of the conventional processed steel. The metastable austenite transformes gradually with the increase of aging temperature. The peak aging occurs at 570°C with a hardness of HRC 60, which is larger than the hardness HRC38 of the as sprayed steel. The aged steel mainly consists of martensite. Subsequently, with the increase of the aging temperature, the hardness of Cr 12 MoV steel decreases rapidly. The critical aging temperature of the as sprayed Cr 12 MoV steel is 570°C.