Residual thermal stresses in cemented carbide with mesostructure

DOI: 10.62564/M4-NL1500

Nataliya Litoshenko

V.M. Bakul Institute for Superhard Materials, Ukraine


The development of composite materials with mesostructures is a relevant task today [1, 2]. One of the effective methods to increase the workability of products made of WC–Co, WC–Ni, TiC–WC–Co hard alloys is to form a mesostructure in them, which will make it possible to improve physical and mechanical properties and simultaneously achieve high wear resistance and fracture toughness [3], as well as double the value of the strength limit and four times the fracture deformation during compression tests. In hard alloys, the meso-structure consists of mesoelements - an ensemble of carbide particles cemented by a binding metal and a metal phase. The properties of such compositions depend on the composition, structure and state of the mesoelements and the matrix. Carbide products with a mesostructure are promising in the mining industry and mechanical engineering. In particular, using them in hard alloy elements of friction pairs and sealing units, it is possible to achieve the most optimal ratio of wear resistance and fracture toughness. The level of residual thermal stresses in granules and interlayers of mesostructural hard alloys (WC–Со)gran–Со, (WC–Ni)gran–Ni, (TiC–Со)gran–Со, (TiC–Ni)gran– Ni , arising during its cooling from the sintering temperature to room temperature was established by analytical methods. The dependence of local stresses on the content of the binder phase in the granule and hard alloy was studied for a layer thickness equal to 10% of the radius of the granule. With an increase in its content from 15 to 30 wt%, compressive stresses in a WC carbide with a binder content of 3...25 vol% increase from –25 to –366 MPa, and the tensile stresses in the Co layer change from 1134 to 687 MPa. The tensile stress values in the matrix layers are lower than in standard hard alloys of similar brands, in particular for (WC–Ni)gran–Ni – by 69%, and for (WC–Со)gran–Со – by 30%.

Keywords
: residual thermal stresses, cemented carbides, mesostructure, phase composition

Acknowledgments
Not provided

References
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