Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Japan Atomic Energy Agency

Kobelco Research Institute, Inc.

Kiyoshi Kiuchi

Jumpei Nakayama

Tatsuhiko Kusamichi

Ichiro Tsukatani

Ikuo Ioka

Kazutaka Kunii

Kiyoyuki Shiba

Tsuyoshi Noura

Chiaki Kato

Nobutoshi Maruyama

Makoto Tanabe

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.

Precipitation-strengthened Ni-based heat-resistant alloy and method for producing the same

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.

Austenitic welding material, and preventive maintenance method for stress corrosion cracking and preventive maintenance method for intergranular corrosion, using same

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)&#x3c;100 ppm, and Ca&#x3c;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. Subsequently, secondary melting is executed by an electron-beam melting method whereby while the primary ingot is sequentially melted in a water-cooled copper mold at a low pressure, the molten metal as-solidified state is pulled out from an outlet side of the water-cooled copper mold, thereby forming an ingot product.

Induction melting apparatus employing halide type crucible, process for producing the crucible, method of induction melting, and process for producing ingot of ultrahigh-purity Fe-, Ni-, or Co-based alloy material

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Ibaraki, Japan

Kiyoshi Kiuchi