Reason for Pickling Cracking of Tapered Forging of Austenitic Stainless Steel

Several circumferential cracks were observed on the localized tapered forgings of austenitic stainless steel after pickling. To find the reason for cracking, the forging process was investigated, and the chemical composition, tensile properties, non-metallic inclusions, microstructure, micromorphology and micro-area composition at different positions were analyzed. The results show that an abnormal structure containing martensite existed in the tapered forgings of austenitic stainless steel. The abnormal structure was corroded during the pickling process, leading to the formation of the circumferential crack belts. The measures, such as strengthening quality control during melting process and performing microstructure examination during manufacturing process, were proposed to prevent the formation of martensite. No pickling cracks appeared after taking these measures.