Numerical Study On The Pitting Characteristics Of Stainless Steel Based On Lattice Boltzmann Method

The stainless steel pipe will be perforated due to pitting corrosion,fracturing under the action of internal and external pressure.Pitting affects the service life of oil and gas pipelines.It is extraordinary significant to mitigate pitting corrosion for oil and gas pipeline transportation safety.Numerical study on the pitting corrosion of stainless steel immersed in neutral solution was carried out.The LB corrosion model was established on the basis of the actual reaction mechanism of stainless steel pitting immersed in a neutral solution,the liquid flow transfer characteristics and the principle of phase transformation.The corrosion model was used to simulate the whole pitting process for obtainning pitting pit morphology and the concentration distribution of different components in different pitting stages.The evolution of pitting of stainless steel was simulated by LBM corrosion model.The results showed that the pitting degree of stainless steel increased with the simulation time,and there was a turning point of increasing corrosion rate.The effects of different parameters on the pitting progress were obtained by changing the simulated conditions.The results showed that the tendency of pitting nucleation increased with the rate of nucleation reaction and the increase of chloride ion concentration.The metastable degree of pitting increased with the increase of initial oxygen concentration and the corrosion reaction rate.The degree of steady state pitting increased with the increase of steady state pitting rate and oxygen diffusion coefficient.In addition,the effect of corrosion products on steady pitting corrosion was also studied.The results showed that the degree of stainless steel pitting and the weight of the precipitated corrosion products at the opening of pit decreased with the increase of saturation concentration of corrosion products,with the decrease of deposition rate of corrosion products,and with the increase of diffusion coefficient of corrosion products.The LB corrosion model provides a new idea for the numerical study on metal corrosion.