Abstract
In order to evaluate the thonghness of cemented carbides, the influence of surface finishing on crack length at vickers indetations was studied.
The results are as follows.
(1) Grinding introduces deformed surface layer. The heavier the grinding, the shorter the crack length. The increase in crack length resulting from polishing is caused by the removal of the surface layer produced in grinding.
(2) Annealing at temperatures about 800°C removes the damage produced in grinding and polishing. Crack length in a given alloy reaches a maximum if the specimens are annealed after polishing.
(3) This maximum crack length should be used in evaluating parameters for the crack resistance of an alloy.
The crack resistance, which is independent of the indentation load and of the hardness of the alloy serves to evaluate the toughness of cemented carbides.
