The influence of deoxidation on the properties of stainless steel

1. With a content in the steel of more than 0.08% residual aluminum the ductility at 900–1250°C is poorer and the tendency toward embrittlement at temperatures below 20°C increases. 2. An increase in the aluminum content aids in the formation in hardened steel of M2N nitrides and after tempering at 800°C of A1N phase. A drop in the ductility and toughness, especially at low temperatures, is caused primarily by the precipitation of nitride phases. 3. Calcium in a calculated quantity of 0.1–0.15% increases the ductility of the steel at hot working temperatures and does not influence the mechanical properties from 20 to −253°C. 4. An increase in the silicon content in the steel over 0.45% causes the appearance after heating to 1250–1350°C of a eutectic with an increased content of silicon and manganese. Heating after working should not exceed 1250°C. 5. To provide statisfactory production conditions for the investigated steel in hot working in combination with sufficiently high strength and ductility from 20 to −253°C the aluminum content in the steel should not exceed 0.06% and that of silicon 0.4%. For final deoxidation it is desirable to use calcium equal to 0.1–0.15% of the weight of the steel.