Microstructure and properties of plasma additive low carbon Bainite steel

The mechanical properties and microstructure of well-formed bainite steel members were studied using a plasma arc additive process. The results show that the microstructure of the additive component mainly comprised strip bainite, granular bainite, and a small amount of austenite. There were local differences in the microstructure and mechanical properties of the additive members. The microstructure at the top of the structure was mostly coarse grains, mainly composed of strip bainite and austenite, with an average microhardness of about 365 HV. The grain at the bottom was fine, mostly granular bainite, with an average microhardness of about 384 HV. The average impact toughness of the whole component was 145 J/cm², and the average tensile strength and elongation reached 955 MPa and 11.7%, respectively. The tensile strength in the x direction was 945 MPa, slightly lower than that in the y direction (963 MPa) and z direction (958 MPa). This showed no obvious anisotropy in tensile strength, and fracture was ductile.