Sumitomo Metal Industries, Inc.

Hideaki Miyuki

Hideo Yamamoto

Yoshiaki Kusaba

Shigeki Azuma

A method for improving the resistance to surface roughening of tungsten-containing metallic articles such as cutting tools and hot mill rolls made of a cemented carbide or high-speed steel and extending the lifetime thereof. The method comprises treating a metallic article with an aqueous alkaline solution containing calcium ions and optionally tungstate ions having a pH greater than 8 so as to form a coating of calcium tungstate on the surface of the metallic article. In hot rolling with tungsten-containing rolls, the aqueous solution can be used as at least part of a cooling water to cool the rolls, thereby extending the period before roll replacement becomes necessary due to surface roughening and decreasing the frequency of roll dressing required during hot rolling.

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Kobe, Japan

Hideaki Miyuki