Thickness effect on the ductile fracture properties of the vessel steel with small punch testing techniques

摘要

Small Punch (SP) tests were carried out at room temperature on round thin specimens with six kinds of thicknesses.Experimental results show that both the fracture strain and the fracture toughness increase with the thickness of the SP samples. From the view point of the energy dissipation and the primary mechanical definition of the fracture toughness,a fundamental theoretical model is proposed according to which the ductile fracture toughness is obtained with the total energy and the plastic deformation. The fracture strain and the fracture energy density criterions are introduced into the local failure model. With the continuum damage model,the FEA simulations with the local failure criterion get the results of the crack propagation process which agree with the experimental results. The simulation results show that with the increment of the thickness the fracture strain increases,and the fracture strain decreases due to the increment of the stress triaxiality