Effect of local heat treatment on microstructure and statics properties of clinched joints for SPCC steel

Local heat treatment was performed on the clinched joints by building an experiment apparatus for local heat treatment. The metallographic specimens were prepared to observe the microstructure of the specimen with heat treatment. The microhardness was measured on the specimens with heat treatment or without. The influence of heat treatment on the static tensile strength of clinched joints was analyzed by comparing two groups of specimen with heat treatment or the one without heat treatment. The results showed that the material of the clinched joints had martensitic structure after heat treatment. The static strength of the clinched joints was promoted largely owing to the martensitic structure compared to the ferrite and pearlite structure of clinched joints had not been treated.