Effect of prestrain on the fracture toughness of steel 16MnR

The prestrain on 16MnR steel was found experimentally to influenceupon its fracture toughness remarkably. During fracturing, the microstructural chan-ge was taken place in the crack tip zone, The cracks will propagate on the second-ary pearlite structure. It is believed that the fracture toughness of 16MnR steel isdependent on the diffusion of carbon atoms and the formability of secondary pearl-ite structure.