Abstract: Thermo-Calc thermodynamic simulation was utilized to analyze the solidification behavior and the phase transition temperature of low nickel stainless steel. Gleeble-3800 thermal simulator was applied to study the high temperature plasticity, EPMA was adopted to study the microstructure and chemical composition of the coil surface crack defects. The results show that there exists the peritectic reaction for low nickel austenitic stainless steels, which is similar to the low carbon steels. The peritectic reaction would lead to the reduction of high temperature plasticity and therefore the high risk of surface longitudinal crack of slab. Based on these studies, the chemical composition of low nickel austenitic stainless steel was optimized. After optimizing the composition, longitudinal crack of slab decreased from 8.92 % to 2.64 %，and the surface crack of coil decreased from 12.45 % to 3.77 %.

Key words: thermodynamic software Thermo-Calc, low nickel austenitic stainless steel, high temperature plasticity, longitudinal crack of slab, surface crack