Factors Affecting on Mechanical Properties of Soft Martensitic Stainless Steel Castings

This paper details the factors affecting mechanical properties of soft martensitic stainless steel castings that have lower carbon contents and increased nickel contents of up to 6% compared with normal martensitic stainless steel castings. The effect of alloying elements and impurities on the microstructural features and tempering characteristics was considered in detail, with special reference to reverted austenite and temper embrittlement. The mechanical properties were also investigated, and it was shown that the best combination of strength and toughness is obtained when tempered at around 900K. Addition of Mo was shown to improve toughness degradation due to slow cooling from the tempering temperature. Lowering P and S contents leads to superior toughness and fatigue properties. The threshold stress intensity range was shown to decrease with increasing stress ratio, depending on P content.