Hisashi Suzuki1, Koji Hayashi1, Yasuro Taniguchi1 and Hideaki Matsubara1
1Department of Metallurgy and Materials Science, Faculty of Engineering, University of Tokyo, Tokyo
The deformation characteristics and transverse-rupture strength (T.R.S.) of WC-(1∼30)% Co cemented carbides with medium carbon were studied at 873∼1273 K by means of the three-point bend test at a crosshead speed of 8.3×10-6 m/s; attention was paid to the effects of the carbide grain size (1.3∼3.8 μ m) and domain size of the binder phase.
The following results were obtained: (1) The deformation of cemented carbides was generally divided into two parts, that is, the true deformation part under comparatively low stresses and the other part including apparent deformation (due to stable cracks formation) under high stresses. (2) In the alloy with a fixed cobalt content, the deformation became suppressed at high temperatures, in particular at 1273 K, with increasing carbide grain size, leading to the increase in T.R.S. in coarse grained alloy. The phenomena were in contrast to those at low temperatures. The above results at high temperatures would be explained by assuming that dynamic recovery in the binder was apt to be arrested with increasing carbide grain size. (3) Independent of test temperatures, the amount of the apparent deformation became smaller in case of coarse domain size and at the same time T.R.S. increased, owing to the fact that stable cracks could not easily grow along domain boundaries. (4) As a result, it was made clear that T.R.S. of cemented carbides was precisely understood, when bend-deformation behaviors generally affected by the structural factors were taken into consideration.
Please do not copy without permission.