Abstract: The object of the present invention is to provide a heat-resistant steel for exhaust valves, having relatively small Ni content, high mechanical characteristics (for example, tensile strength, fatigue strength, wear resistance and hardness) at high temperature, and excellent oxidation resistance. The present invention provides a heat-resistant steel for exhaust valves, which includes: 0.45?C<0.60 mass %, 0.30<N<0.50 mass %, 19.0?Cr<23.0 mass %, 5.0?Ni<9.0 mass %, 8.5?Mn<10.0 mass %, 2.5?Mo<4.0 mass %, 0.01?Si<0.50 mass %, and 0.01?Nb<0.30 mass %, with the balance being Fe and unavoidable impurities, in which the steel satisfies 0.02?Nb/C<0.70 and satisfies 4.5?Mo/C<8.9.

Abstract: The object of the present invention is to provide a heat-resistant steel for exhaust valves, having relatively small Ni content, high mechanical characteristics (for example, tensile strength, fatigue strength, wear resistance and hardness) at high temperature, and excellent oxidation resistance. The present invention provides a heat-resistant steel for exhaust valves, which includes: 0.45?C<0.60 mass %, 0.30<N<0.50 mass %, 19.0?Cr<23.0 mass %, 5.0?Ni<9.0 mass %, 8.5?Mn<10.0 mass %, 2.5?Mo<4.0 mass %, 0.01?Si<0.50 mass %, and 0.01?Nb<0.30 mass %, with the balance being Fe and unavoidable impurities, in which the steel satisfies 0.02?Nb/C<0.70 and satisfies 4.5?Mo/C<8.9.

Abstract: The present invention provides a heat resistant steel for an exhaust valve, containing: more than 0.50% by mass but less than 0.80% by mass of C, more than 0.30% by mass but less than 0.60% by mass of N, 17.0% by mass or more but less than 25.0% by mass of Cr, 4.0% by mass or more but less than 12.0% by mass of Ni, 7.0% by mass or more but less than 14.0% by mass of Mn, 2.0% by mass or more but less than 6.0% by mass of Mo, more than 0.5% by mass but less than 1.5% by mass of Si, and 0.025% by mass or more but less than 1.0% by mass of Nb, with the balance consisting of Fe and unavoidable impurities, in which a content of P contained in the unavoidable impurities is regulated to less than 0.03% by mass, a total content of C and N is from 0.85% by mass to 1.3% by mass, and a ratio of the content of Nb to the content of C is 0.05 or more but less than 1.8.

Abstract: There are disclosed a laser clad valve seat raw-material powder superior in productivity, cladding property, wear resistance and finishing property, and a laser clad valve seat using the same superior in wear resistance. The row-material powder comprises a powder mixture comprising: 80 to 99% by weight of a Cu-based alloy powder comprising 0.5 to 5% by weight of B, 0 to 20% by weight of Ni, 0 to 10% by weight of Fe plus Co, 0 to 5% by weight of Si, 0 to 3% by weight of Al, and the balance Cu and unavoidable impurities; and 1-20% by weight of an Fe or Co based alloy powder having a Vickers hardness of 500 HV or higher and an average particle diameter of 50 to 200 ?m of and comprising 5 to 40% by weight of Mo, 0 to 25% by weight of Cr, 0 to 5% by weight of Si, and the balance Fe or Co and unavoidable impurities.

Abstract: There are disclosed a laser clad valve seat raw-material powder superior in productivity, cladding property, wear resistance and finishing property, and a laser clad valve seat using the same superior in wear resistance. The row-material powder comprises a powder mixture comprising: 80 to 99% by weight of a Cu-based alloy powder comprising 0.5 to 5% by weight of B, 0 to 20% by weight of Ni, 0 to 10% by weight of Fe plus Co, 0 to 5% by weight of Si, 0 to 3% by weight of Al, and the balance Cu and unavoidable impurities; and 1-20% by weight of an Fe or Co based alloy powder having a Vickers hardness of 500HV or higher and an average particle diameter of 50 to 200 ?m of and comprising 5 to 40% by weight of Mo, 0 to 25% by weight of Cr, 0 to 5% by weight of Si, and the balance Fe or Co and unavoidable impurities.