Fracture Analysis of Expanded Mouth of 1Cr17Ni2 Stainless Steel Shafts

During the expansion of 1Cr17Ni2 stainless steel shaft, cracking frequently occurred at the expended mouth. Through metallurgical examination on several batches of 1Cr17Ni2 stainless steel shafts, the failure cause was analyzed. The results indicate that serious blowholes and pinholes are one of the main causes for the failure. The high content of δ-ferrite in the 1Cr17Ni2 steel is another main reason. The lower content and the smaller size of δ-ferrite the 1Cr17Ni2 steel has, the smaller the possibility for the cracking of the expanded mouth is. With the frequencies of heat treatment increasing, the content of δ-ferrite in the 1Cr17Ni2 steel after quenching would significantly increase.