Tool Wears during Cutting 18-8 Type Stainless Steel with WC-TiC-10%Co Alloy Tools

Abstract

The 18-8 type stainless steels are known as materials difficult to machine. The causes and counter-measures, however, have never been studied in relation to the metallurgical factors of cemented carbides. Therefore, the wear processes of WC-TiC-10%Co alloy tools in the cutting of stainless steels were investigated with particular attention to the grain size of WC and β phases, and carbon content, titanium carbide and impurity contents.
The main results obtained were as follows:
(1) Different mechanisms between cratering wear and outside wear were found to exist, and clearance wear was caused by the plastic deformation of the tools.
(2) With increasing titanium carbide content, cratering wear, plastic deformation and clearance wear were all decreased with the exception of outside wear.
(3) In the case of high speed cutting, low carbon WC-10%TiC-10%Co alloy tools showed better resistance to all the wears than high carbon alloy tools. With increasing grain size of the β phase and decreasing grain size of the WC phase, the resistance to cratering and clearance wears was highly improved.
(4) In sum, it was found that the WC-TiC-Co alloy tools showing high resistance to the various wears in high speed cutting of stainless steels, should be developed in the alloys with low carbon content, fine grain size of WC and coarse β phases. These results may be applied to WC-TiC-TaC-Co alloy tools.