Abstract: The present invention relates to a powder for additive manufacturing, having a composition consisting of, in mass %: 0.25<C<0.40, 0.001?Si?0.15, 0.30?Mn?0.45, 5.0?Cr?5.5, 1.0?Mo?1.5, 0.35?V?0.45, 0.01?N?0.05, 0.01?O?0.04, and optionally, P<0.10, Cu<0.20, Ni<0.20, Al<0.05, Zr<0.05, S<0.20, Pb<0.20, Bi<0.20, Nb<0.20, Ti<0.20, B<0.10, and Co<0.20, with the balance being Fe and unavoidable impurities, in which a surface of the powder for additive manufacturing is coated with an oxide film, and the oxide film has a thickness of 3 nm or more and 30 nm or less.

Abstract: To provide a steel for plastic molding die which possesses enough hardness, wear resistance and corrosion resistance, and is excellent in high-precision processability and mirror polishing properties. The steel for a plastic molding die contains not more than 0.80 wt % C, not less than 0.01 wt % and less than 1.40 wt % Si, not less than 0.05 wt % and not more than 2.0 wt % Mn, not less than 0.005 wt % and not more than 1.00 wt % Ni, not less than 13.0 wt % and not more than 20.0 wt % Cr, not less than 0.20 wt % and not more than 4.0 wt % Mo+½ W, not less than 0.01 wt % and not more than 1.00 wt % V, not less than 0.36 wt % and not more than 0.80 wt % N, not more than 0.02 wt % O, not more than 0.80 wt % Al, and the remainder substantially including Fe and unavoidable impurities.