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Structure and properties of tool gradient materials reinforced with the WC carbides

100%

Dobrzański L. A. , Dołżańska B. , Matula G.

tom Vol. 28, nr 1

35-38

Purpose: The purpose of the paper is to describe sintered Tool Gradient Materials manufactured by powder metallurgy process. The Powder Metallurgy method has been chosen to manufacture tool gradient materials with high disproportion of cobalt matrix portion between core and surface layer. Design/methodology/approach: Forming methods were developed during the investigations for tungsten carbide and cobalt, making it possible to obtain materials wits five layers in their structure. Findings: High diversification of cobalt matrix portion in comparison to hard phases in subsequent layers of gradient materials leads to their deformation in as sintered state. In case of all gradient materials, mean hardness was equal about 1750 HV1. Whereas, hardness of lower cobalt matrix rich layers is about 1548 HV1 and increased up to 2154 HV1 for lower layer of material rich with hard carbide phases. The porosity decreases along with the carbon content in these layers. Practical implications: Material presented in this paper is characterized by very high hardness of the surface and relative ductility of core. TGM with a smooth changes of the cobalt phase in the material. Originality/value: The obtained results show the possibility of manufacturing of TGM on basis of different portion of cobalt reinforced with hard ceramics particles carried out in order to improve the abrasion resistance and ductility of tool cutting materials.

The computer simulation of internal stresses of tool gradient materials reinforced with the WC-Co

100%

Dobrzański L. , Kwaśny W. , Dołżańska B.

tom Vol. 57, nr 1

38-44

Purpose: The general topic of this paper is the computer simulation with the use of finite element method for determining the internal stresses in tool gradient materials WC-Co obtained in the powder metallurgy process in different temperatures of 1400°C + HIP and 1460°C + HIP. Design/methodology/approach: The following research studies have been carried out a new group of sintered tool gradient materials, tungsten carbide with cobalt matrix, modeling of stresses was performed used of finite elements method in ANSYS environment, and the experimental values of stresses were determined basing on the X-ray diffraction patterns. Findings: The developed model of the tool consists of four layers with different contents of tungsten carbide and the concentration of cobalt by using the finite element method allows to simulate the impact of sintering temperature on the stress occurring in the material. On the basis of the model, it was found that by properly controlled treatment technology, able to induce compressive stresses in the surface layer of material, thus increasing the resistance of the material on the formation and propagation of cracks. Research limitations/implications: It was confirmed that using of finite element method can be a way for Computer simulation of stresses, strains and displacements of the fabricated gradient material depending on the sintering temperature. Results reached in this way are satisfying and in slight degree differ from results reached by experimental method. However for achieving better calculation accuracy in further researches it should be developed given model which was presented in this paper. Originality/value: The obtained results show the possibility to manufacture TGMs on the basis of different portions of cobalt reinforced with hard ceramics particles in order. The computer simulation is based on the finite element method, which allows to better understand the interdependence between parameters of process and choosing optimal solution.

Characteristics of structure and properties of a sintered graded tool materials with cobalt matrix

63%

Gołombek K. , Matula G. , Dobrzański L. A. , Dołżańska B.