Abstract: The present invention provides a Ni-based alloy, a heat-resistant and corrosion-resistant component, and a heat treatment furnace component, all of which have excellent corrosion resistance and mechanical strength at high temperatures. The Ni-based alloy of the present invention consists of, by mass %, Al: more than 5.0% and up to 26.0%, and Zr: more than 0% and up to 5.0%, the balance being Ni and unavoidable impurities. The Ni-based alloy preferably contains more than 0% and up to 5.0% of B, by mass %, in a combined amount with Zr. Moreover, it is preferable that the Ni-based alloy has P value and Q value and satisfies a relationship of Q value ? 0.89 × P value - 0.53, when the P value is obtained from a formula -18.95 + 0.1956 × Ni% + 0.1977 × Al% + 0.2886 × Zr% + 12.4 × B%, and the Q value is obtained by dividing an area percentage of Ni3Al precipitated on the surface of the alloy by 100.

Abstract: The present invention provides a steel product that has excellent oxidation resistance on a surface thereof that is to come into contact with a steel material and that also has excellent weldability. The steel product for use in contact with a steel material according to the present invention is a steel product for use in contact with a steel material, the steel product including a centrifugally-cast portion formed on a surface of the steel product that is to come into contact with the steel material, the centrifugally-cast portion being made through centrifugal casting, and a statically-cast portion to which the centrifugally-cast portion is welded, the statically-cast portion being formed through static casting, the centrifugally-cast portion containing, in terms of mass %, C: 0.2% to 0.7%; Si: more than 0% and 2.0% or less; Mn: more than 0% and 3.0% or less; Cr: 15.0% to 40.0%; Ni: 18.0% to 55.0%; Al: 1.0% to 5.5%; and at least one type selected from the group consisting of Ti: 0.01% to 0.6% and/or Nb: 0.

Abstract: The present invention provides a heat-resistant alloy and a reaction tube having excellent oxidation resistance, excellent mechanical properties such as tensile ductility, and weldability. A heat-resistant alloy of the present invention comprises, in terms of % by mass, C: 0.35% to 0.7%, Si: more than 0% and 1.5% or less, Mn: more than 0% and 2.0% or less, Cr: 22.0% to 40.0%, Ni: 25.0% to 48.3%, Al: 1.5% to 4.5%, Ti: 0.01% to 0.6%, and the balance being Fe and inevitable impurities, wherein when Pa=?11.1+28.1×C+29.2×Si?0.25×Ni?45.6×Ti, and Ya=?13.75×Al+63.75, Pa<Ya.

Abstract: The present invention provides a Co-free heat-resistant alloy for a hearth metal member that has properties superior to or equal to those of Co-containing heat resistant steel. The heat-resistant alloy for a hearth metal member according to the present invention is a heat-resistant alloy used in a hearth metal member of a steel heating furnace, the heat resistant alloy containing: 0.05% to 0.5% of C; more than 0% and 0.95% or less of Si, where 0.05%?C+Si?1.0%; more than 0% and 1.0% or less of Mn; 40% to 50% of Ni; 25% to 35% of Cr; 1.0% to 3.0% of W; and 10% or more of Fe and inevitable impurities as the balance, with all percentages being in mass %. The heat-resistant alloy for a hearth metal member may further contain 0.05% to 0.5% of Ti and/or 0.02% to 1.0% of Zr, with all percentages being in mass %.

Abstract: The present invention provides a Co-free heat-resistant alloy for a hearth metal member that has properties superior to or equal to those of Co-containing heat resistant steel. The heat-resistant alloy for a hearth metal member according to the present invention is a heat-resistant alloy used in a hearth metal member of a steel heating furnace, the heat resistant alloy containing: 0.05% to 0.5% of C; more than 0% and 0.95% or less of Si, where 0.05% ?C+Si?1.0%; more than 0% and 1.0% or less of Mn; 40% to 50% of Ni; 25% to 35% of Cr; 1.0% to 3.0% of W; and 10% or more of Fe and inevitable impurities as the balance, with all percentages being in mass %. The heat-resistant alloy for a hearth metal member may further contain 0.05% to 0.5% of Ti and/or 0.02% to 1.

Abstract: The present invention provides a heat-resistant alloy and a reaction tube having excellent oxidation resistance, excellent mechanical properties such as tensile ductility, and weldability. A heat-resistant alloy of the present invention comprises, in terms of % by mass, C: 0.35% to 0.7%, Si: more than 0% and 1.5% or less, Mn: more than 0% and 2.0% or less, Cr: 22.0% to 40.0%, Ni: 25.0% to 48.3%, Al: 1.5% to 4.5%, Ti: 0.01% to 0.6%, and the balance being Fe and inevitable impurities, wherein when Pa=?11.1+28.1×C+29.2×Si?0.25×Ni?45.6×Ti, and Ya=?13.75×Al+63.75, Pa<Ya.