Kabushiki Kaisha Kobe Seiko Sho

Hiroyuki Uchida

Eiji Takahashi

Kazuo Yoshikawa

Seiji Nishi

Masaaki Katsumata

Yoji Matsumoto

Hideaki Ohtsu

Isamu Takagi

Kiyoshi Asami

Tadamichi Sakai

Disclosed is a method of lowering the permeability of a difficult-to-work Co alloy by introducing high working strain. It includes the steps of: making a Co alloy by melting, the Co alloy containing 0.1 to 40 atomic % of Ni and/or 0.1 to 40 atomic % of Pt, and 0.5 to 10 atomic % of one or more kinds of elements selected from a group consisting of Ta, Mo, W, V, Nb, Hf, Zr, Ti and B (the upper limit of B: 5 atomic %), the balance being 50 atomic % or more of Co and inevitable impurities; preparing a sheet like ingot having a thickness of 30 mm or less using the Co alloy; and covering the surface of the ingot with a metal capsule or coating it with a glass lubricant, and hot-rolling the treated ingot in such a manner that the reduction is performed in two stages accompanied by re-heating and the whole reduction is 30% or more.

Method of lowering permeability of difficult-to-work Co alloy

Low alloy steels for use in pressure vessel comprising on the weight % basis:

Low alloy steels for use in pressure vessel

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Kobe, Japan

Hiroyuki Uchida