Abstract
The strength of three sorts of cemented carbides coated with TiC by CVD process was studied mainly relating to the carbide grain size. It was found that the strength of coated alloys was almost not influenced by the carbide grain size, in contrast to that of substrates which decreased with increasing the grain size. It was also found that whether the substrate was HIP-treated or not, had no relation to the strength of coated alloys. The result of milling test for the coated P30 alloy showed that the resistance to fracture of cutting edge was greatly improved with increasing the carbide grain size, the tendency being different from that of the strength of coated alloys.
The above phenomena as well as the decrease in strength generally observed in coated alloys were discussed in detail.
