Abstract: A precipitation-strengthened Ni-based heat-resistant alloy of the present invention includes 0.03 wt % or less of C, 0.5 wt % or less of Mn, 0.01 wt % or less of P, 0.01 wt % or less of S, 2.0 to 3.0 wt % of Si, 23 to 30 wt % of Cr, 7.0 to 14.0 wt % of W, 10 to 20 wt % of Fe, and 40 to 60 wt % of Ni, wherein a total content of C, N, O, P and S is 0.01 wt % or less. A silicide is dispersed and precipitated and a grain size of a matrix austenite is controlled through a thermo-mechanical treatment. As a result, the precipitation-strengthened Ni-based heat-resistant alloy excellent in irradiation resistance, heat resistance and corrosion resistance can be obtained with a low cost.

Abstract: A precipitation-strengthened Ni-based heat-resistant alloy of the present invention includes 0.03 wt % or less of C, 0.5 wt % or less of Mn, 0.01 wt % or less of P, 0.01 wt % or less of S, 2.0 to 3.0 wt % of Si, 23 to 30 wt % of Cr, 7.0 to 14.0 wt % of W, 10 to 20 wt % of Fe, and 40 to 60 wt % of Ni, wherein a total content of C, N, O, P and S is 0.01 wt % or less. A silicide is dispersed and precipitated and a grain size of a matrix austenite is controlled through a thermo-mechanical treatment. As a result, the precipitation-strengthened Ni-based heat-resistant alloy excellent in irradiation resistance, heat resistance and corrosion resistance can be obtained with a low cost.

Abstract: Disclosed is an austenitic welding material which contains C: 0.01 wt % or less, Si: 0.5 wt % or less, Mn: 0.5 wt % or less, P: 0.005 wt % or less, S: 0.005 wt % or less, Ni: 15 to 40 wt %, Cr: 20 to 30 wt %, N: 0.01 wt % or less, O: 0.01 wt % or less, and the balance of Fe and inevitable impurities, wherein the content of B contained as one of the inevitable impurities in the welding material is 3 wt ppm or less, and the total content of C, P, S, N and O in the welding material is 0.02 wt % or less.

Abstract: Disclosed is an austenitic welding material which contains C: 0.01 wt % or less, Si: 0.5 wt % or less, Mn: 0.5 wt % or less, P: 0.005 wt % or less, S: 0.005 wt % or less, Ni: 15 to 40 wt %, Cr: 20 to 30 wt %, N: 0.01 wt % or less, 0: 0.01 wt % or less, and the balance of Fe and inevitable impurities, wherein the content of B contained as one of the inevitable impurities in the welding material is 3 wt ppm or less, and the total content of C, P, S, N and O in the welding material is 0.02 wt % or less.

Abstract: There is described a method for producing ultrahigh-purity Fe-base, Ni-base, and Co-base alloying materials to achieve impurity levels of (C+O+N+S+P)<100 ppm, and Ca<10 ppm, in the form of a large ingot, using a refining flux while forcibly cooling the crucible. A refining flux selected from the group consisting of metal elements of the Groups IA, IIA, and IIIA of the Periodic Table, oxides thereof, halides thereof, and mixtures thereof, is added to the molten metal during primary melting and the molten metal is held in contact with the refining flux for at least 5 minutes before tapping. Thereafter, the molten metal is caused to undergo solidification inside a mold, thereby producing a primary ingot.

Abstract: An austenitic stainless steel excellent in intergranular corrosion resistance and stress corrosion cracking resistance, comprising: C: 0.005 wt % or less; Si: 0.5 wt % or less; Mn: 0.5 wt % or less; P: 0.005 wt % or less; S: 0.005 wt % or less; Ni: 15.0 to 40.0 wt %, Cr: 20.0 to 30.0 wt %, N: 0.01 wt % or less; O: 0.01 wt % or less; and the balance of Fe and inevitable impurities, wherein the content of B included in the inevitable impurities is 3 wt ppm or less.

Abstract: There is provided an induction-melting apparatus capable of exhibiting high refining performance without inflicting damage to a crucible even if a halide-compound base refining flux is used upon induction-melting of an ultrahigh-purity high melting-point metal, having a melting point reaching 1500° C., and a method for induction-melting using the same. There is also provided a melting method for enabling production of ultrahigh-purity Fe-base, Ni-base, and Co-base alloying materials, each having an impurity level of (C+O+N+S+P)<100 ppm, and Ca<10 ppm, and in the form of a large ingot. Further, with the induction-melting apparatus, a plurality of tubular segments are disposed so as to be cylindrical in shape, a gap in a range of 1.