Abstract
Some austenitic heat resisting steels containing 0.2% phosphorus for exhaust valves have been evaluated by stress-rupture test at 650, 750 and 800°C, short time tensile test at room and high temperature, hot hardness test, lead oxide crucible test and scaling test. The addition of 0.2% phosphorus increases the precipitation hardening effect produced by carbide precipitation and results in marked improvement of rupture strength. The steel containing 0.3% C, 20% Cr, 11% Ni, 2% Mo, 0.2% P and 0.01% B has a good combination of strength and ductility, and is found suitable for heavy duty exhaust valves.
