To evaluate the behavior of strength degradation of corroded steel with pitting evolution, an insitu pitting evolution method is achieved by ABAQUS software combined with Python program based on pit statistics on steel matrix surfaces at different corrosion times. Following this, the stochastic pitting evolution method for assessing the mechanical properties of corroded steel is proposed. Then, on the premise of the consistent mass loss rates between the numerical model and the test, the accuracy and applicability of numerical results of strength of corroded steel are analysed and verified. Also, a model of strength degradation created by corrosion pits is established. In addition, the degradation laws of yield and ultimate strengths of corroded Q235 steel under the joint influence of mass loss rate and corrosion depth

are systematically investigated. Successively, the generalized equations for the evolution of yield and ultimate strengths of corroded steel with the mass loss rate and corrosion depth are proposed. The results show that when the pit depth is known, the residual strength decreases exponentially with the mass loss rate. The yield strength and ultimate strength of steel under the influence of pitting corrosion can be calculated by mass loss rate and pit depth together.