Analysis of Edge Crack Defect Analysis and Control of 316L Austenitic Stainless Steel

Abstract

During the hot deformation process, austenitic stainless steel is prone to defects such as edge cracking and edge damage. The effects of heating temperature and holding time on the second phase in the high-temperature structure of 316L austenitic stainless steel during thermal deformation were investigated. The results show that there is a large amount of net ferrite in the edge triangle of hot rolling at 1150 °C, and the ferrite–austenite two-phase zone exists in the 316L austenitic stainless steel at high temperature. In the subsequent heating process, the content of high-temperature ferrite further increases, leading to the reduction in plasticity and the formation of edge crack in the rolling process. And as the deformation temperature increases, the deformation substructure and twin boundaries in the grains gradually decrease, and at 1200 °C, the grain size is significantly smaller than that at other temperatures. When the sample is subjected to small reduction and multi-pass hot rolling, the tendency for edge cracking decreases. When the heating temperature exceeds 1200 °C, the austenite growth rate decreases. There is a certain amount of ferrite in the microstructure of the rolled sample, and as the insulation time increases, the size of ferrite gradually increases. At 1150 °C, the content of ferrite decreases with the increase in holding time, and the grain size of austenite increases obviously at 90-min holding time. The high-temperature phase diagram of the experimental steel was simulated by Thermo-Calc. The calculated results are in good agreement with the experimental ones.