Influence of Microstructure of Steel on Diamond Tool Wear

Excessive tool wear occurs when commercial steels are single-point diamond turned. Therefore, the development of diamond turnable steel is expected in the manufacture of molds for complex and precise optical components. As an initiate approach to this subject, various kinds of quenched and tempered steels were turned using single-crystal diamond tools, and tool wear measurement was made with a scanning electron microscopy. As a result, the various amounts of coner wear was observed by the diamond tool, and the width of wear was found to be different in a kind of steels. In order to clear up this cause, constituent phase analysis of the steels used in the turning experiments was carried out by X-ray diffraction. It gave that their microstructures differed considerably from steel to steel and were classified into four group, those are alpha-ferrite, alpha-ferrite + gamma-austenite, gamma-austenite, and alpha-ferrite + such carbides as Fe3C, Cr23C6 and WC. On the basis of these results, the inductive inference methodology was applied to the tool wear measurement and phase analysis. From the results, the steel whose microstructure consists of particle carbide precipitation on alpha-ferrite matrix, e.g. JIS SK85, SUS420J2, SKS3 etc., suppresses diamond tool wear because the carbides prevent carbon diffusion into iron in turning of steel.