等离子弧增材制造双金属交织结构微观组织及力学性能

Microstructure and mechanical properties of bimetallic intertexture structure fabricated by plasma arc additive manufacturing

以18Ni高强钢和高氮奥氏体不锈钢为丝材,采用等离子弧增材制造高强钢-高氮钢双金属交织结构,通过对高强钢-高氮钢双金属交织结构的微观组织观察、显微硬度及抗拉强度等力学性能试验研究了双金属交织结构的组织转变特征及其与力学性能关系.结果表明,在高氮钢区域显微组织主要为奥氏体等轴晶及树枝晶,高强钢区域为板条状马氏体.高强钢区域硬度变化范围为480~500 HV;高氮钢区域硬度变化范围为310~320 HV.拉伸试验结果表明,交织结构在x向抗拉强度均值为1092 MPa,略低于y向抗拉强度1189 MPa;x向断后伸长率均值为20.0%,与y向断后伸长率19.5%相差不大;断口呈暗灰色、明显纤维状,分布有大量的等轴韧窝,韧窝尺寸大而深,断口边缘存在明显剪切唇区,属于韧性断裂.

Using 18Ni high strength steel and high nitrogen austenitic stainless steel as wires,bimetallic intertexture structure of high strength steel and high nitrogen steel was fabricated by plasma arc additive manufacturing.The microstructure and mechanical properties of bimetallic intertexture structure of high strength steel and high nitrogen steel were studied by microstructure observation,microhardness and tensile strength test.The results indicate that the microstructure in high nitrogen steel region are mainly equiaxed crystals and dendrite of austenite,the microstructure of high strength steel area is lath martensite.The hardness of the high strength steel area varies from 480 to 500 HV,the hardness of high nitrogen steel area varies from 310 to 320 HV.The tensile test results show that the average tensile strength of the intertexture structure in the x direction is 1092 MPa,which is slightly less than the tensile strength in the y direction of 1189 MPa.The average elongation after fracture in the x direction is 20.0%,which is not much different from the elongation after fracture in the y direction which is 19.5%.The fracture presents dark gray and obviously fibrous,with a large number of equiaxed dimples distributed,the dimples are large and deep,and there is an obvious shear lip area on the edge of the fracture,which is a ductile fracture.