打痕除去後のＷＣ‐Ｃｏ超硬合金工具の表面状態に及ぼす加熱の影響

Abstract

The indentations caused by a hit were often formed on the surface of WC-Co cemented carbide tools such as sleeve, plug, etc., during application. It was found by the authors that, when the tools were heated after removing indentations by grinding, the surface appearance became non-uniform, leading to depreciation of the tools. However, the reason for the above phenomenon seemed not to be studied until now. Then, the model experiment on this subject was carried out, using mainly WC-(10-20)mass%Co specimens. The surface of the specimen was loaded by cemented carbide bar to introduce a groove. Specimens with a groove or specimens ground to remove a groove were heated at different temperatures.It was suggested that the phenomenon was owing to a small amount of surface-growth, because residual elastic strain existing just beneath the indentation was recovered by heating. It was shown that, under a fixed load, the amount of surface-growth became larger and the region where the elastic strain remained was widened in the alloy with higher Co content.