HEAT RESISTANT STEEL FOR EXHAUST VALVE

PROBLEM TO BE SOLVED: To provide a heat resistant steel for an exhaust valve which is relatively low in Ni content an high in mechanical characteristics (for example, tensile strength, fatigue strength, abrasion resistance, hardness, etc.) at a high temperature, and excellent in corrosion resistance.SOLUTION: The heat resistant steel for an exhaust valve comprising the following configuration. (1) The head resistant steel for an exhaust valve comprises, by mass, more than 0.50% but less than 0.80% of C, more than 0.30% but less than 0.60% of N, 17.0% or more but less than 25.0% of Cr, 4.0% or more but less than 12.0% of Ni, 7.0% or more but less than 14.0% of Mn, 2.0% or more but less than 6.0% of Mo, more than 0.5% but less than 1.5% of Si, and 0.025% or more but less than 1.0% of Nb with the balance composed of Fe and unavoidable impurities and has a composition in which a content of P is regulated to less than 0.03 mass%. (2) The head resistant steel for an exhaust valve satisfies 0.85≤C+N≤1.3% by bass. (3) The head resistant steel for an exhaust valve satisfies 0.05≤Nb/C