Coating-workpiece optimization of free cutting steels: turning with TiCN-, ZrO2-, and ZrN-coated cemented carbide tools
1994; Elsevier BV; Volume: 68-69; Linguagem: Inglês
10.1016/0257-8972(94)90250-x
ISSN1879-3347
AutoresJ. von Stebut, A. Darbeı̈da, Jean‐François Lepage, J.M. Brion, Bruno Sander, Gaël Pierson, Jean‐Pierre Bellot,
Tópico(s)Metal and Thin Film Mechanics
ResumoThe mechanism of selective transfer of non-metallic inclusions from a steel wotkpiece to the rake face of the cutting tool, occurring under specific conditions of simultaneous optimization of workpiece material and tool surface chemical composition, is studied by means of inclusion control of the workpiece steel and by deliberate modifications of the chemical composition at the tool surface. Two resulphurized, free cutting steels, one of which has been newly developed with special inclusion control, are selected as workpiece materials. We present metallographic evidence on protective transfer layer (built-up layer (BUL)) formation enhancement for TiCN-, ZrO2- and ZrN-coated K20-type, cemented carbide cutting tools. BUL formation and stability are shown to be dominated by the nature and continuity of the chemically active element on the tool surface. Among the coatings selected in this study, Zr-based coatings are found to be most favourable for tool life enhancement. The sulphide formation enthalpy of the active transition element on the tool surface is concluded to be the major driving force for BUL formation.
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