Effect of Crack Length on Mechanical Field of Stress Corrosion Crack Tip of Cold Working 316L Stainless Steel

Abstract

The effect of crack length at different cold working level on stress and strain state and fracture parameters of stress corrosion cracking tip of 316L stainless steel in high temperature water environment of the nuclear pressure vessel was studied by sub-model technology of elastic plastic finite element method. It combined with the mechanical properties of 316L stainless steel under different cold working level, and the effect of crack length on the Mises stress, equivalent plastic strain, tensile stress, tensile strain and J integral of 316L stainless steel under different cold working level was compared. The results indicate that crack length of stress corrosion cracking has certain effect on stress and strain state at crack tip. With the increase of crack length, Mises stress and equivalent plastic strain, tensile stress and tensile strain increase at crack tip, at the same time, J integral increases with increase of crack length. Cold working level has changed the mechanical properties of 316L stainless steel. When the stress intensity factor K is constant, with the increase of cold working level, Mises stress increases and equivalent plastic strain decreases at crack tip, while tensile stress increases and tensile strain decreases at crack tip. The rate of change of stress strain curve from 0° to 90° is different because of cold working level. The higher the level of cold working, the faster the Mises stress and the tensile stress increase at 90° in front of the crack tip, and equivalent plastic strain and tensile strain decrease most slowly at 90° in front of the crack tip. As the degree of cold working increases, the J integral of crack tip also increases. The increase of crack length and the level of cold working aggravate the stress corrosion cracking of 316L stainless steel under high temperature and high pressure in a certain range.