Selection of heat treatment process and process after friction welding of ductile iron piston

The QT600-7 ductile iron piston after friction welding needs to be annealed at 400 ℃ – 500 ℃ to eliminate the welding stress, and then can be directly processed to make the finished piston. However, its tensile strength is ≥ 600MPa, and its yield strength is ≥ 400MPa, that is, its tensile strength and yield strength are low for the high strength National VI piston, Unable to meet the mechanical property requirements of high-strength national VI piston; Therefore, technicians further studied the heat treatment of QT600-7 ductile iron piston after friction welding and stress relief annealing, which can be quenched, tempered or isothermal quenched.