Microstructure evolution and mechanical properties of linear friction welded 45 steel joint

The microstructure evolution and mechanical properties of Linear Friction Welded (LFW) 45 steel joint under proper conditions was investigated. The microhardness of steel was measured by a Vickers hardness tester with a load of 200 g and the tensile test was conducted using a universal testing machine at a strain rate of 1×10^-4. The results show that the tensile properties of the steel joint is improved in strength and ductility and the fractures of these samples occur in the heat affected zones (HAZ). The relatively large variation of microhardness of quenched 45 steel is associated with the amount of the soft residual austerite after quenching. Microstructures at different position in steel joint shows six types of structures from weld center to the parent metal. The results also show that the microhardness of the 45 steel joint decreases from the parent metal to the weld center.