Abstract：Low-chromium ultrapure ferritic stainless steel is one of the main products of flange steel.Some irregular crack defects were observed in the end of the stamped flange during inspection. The cracks occurred at the end face or single face in the thickness direction. A sample with dimension of 20 mm×20 mm was sampled from the cracking part of flange, and the chemical composition was determined by X-ray fluorescence spectrometer. The section perpendicular to the rolling direction of the sample was polished and etched by FeCl3+HCl mixed acid solution. The microstructure and morphology were observed by optical microscope (OM), and the precipitated phases of sample were analyzed by scanning electron microscope (SEM). The analysis showed that the annealing time at high temperature was too long, resulting in the precipitation of a large number of hard and brittle granular intermetallic compounds (Fe2Ti and Fe3P) in the crystal and grain boundary of the low-chromium ultrapure ferritic stainless-steel matrix. These precipitated phases were irregularly distributed in the form of strips along the thickness direction. The precipitation of these intermetallic compounds, especially the cold brittleness effect of P element, caused the increase of local stress concentration, leading to local cracking during cold working of flanges.
WANG Huatian, DU Huayun, WEI Yinghui, et al. Precipitation and properties at elevated temperature in austenitic heat-resistant steels-A review[J]. Steel Research International,2021,92(2):2000378.
2023, Vol. 41 
