Analysis of Cracking Causes of AISI 416 Martensitic Stainless Steel During Hot Rolling

Delta ferrite and sulfide in martensite steels may adversely affect the high-temperature mechanical properties of the metallic materials. The occurrence of thermal cracking is mainly determined by the chemical composition (e.g., chromium and carbon), microstructure and sulfide morphology in the steel. Thus, the purpose of this study is to evaluate the effects of delta ferrite (δ-Fe) and sulfide morphology on the hot workability of the martensitic AISI 416 stainless steel. Different tests were carried out to analyze the causes for cracking in the hot-working process, with a scanning electron microscope; furthermore, image analyses were also performed for phase characterization and quantification. Results show that the existence of δ-Fe and elongated MnS directly resulted in the formation of cracks and reduced the hot workability of this steel.