[T15] Hard Materials

[16F-T15-03] Tensile Strength of Ultrafine-Grained Cemented Carbide Containing Ti(C,N)

*T.o Tsutsumi^{1, 2}, M. Takada¹, S. Terasaka^{2, 3}, N. Watanabe², H. Matsubara² (1.Nippon Tokushu Goukin., Co., Ltd., Japan, 2.Tohoku University, Japan, 3.Japan Fine Ceramics Center, Japan)

Keywords:ultrafine-grained, cemented carbide, tensile strength, bending strength, Ti(C,N)

The strength of cemented carbides is generally measured by bending tests. However, after the bending test of ultrafine-grained cemented carbides, the specimens were broken in many fragments, so that fracture origin is hard to be observed. This fragmentation prevented a clear understanding of the relationship between the fracture origin and stress, as the precise locations and sizes remained unknown. While bending tests have complicated stress condition with tension, compression and shear, tensile tests are simple about stress condition. Therefore, the purpose of investigation is to clarify the relationship between the fracture origin size and strength by conducting tensile tests on ultrafine-grained cemented carbides. The number of fragments after a tensile test on ultrafine-grained cemented carbide is much less than the number of fragments after a bending test. Therefore, it is possible to observe the fracture origin in tensile tests. As the fracture origin decreased, ultrafine-grained alloy has slightly increased strength.