Finite element analysis of thermal stresses in functionally graded cemented carbides

Abstract

In this study, finite element method and X-ray diffraction measurement were used to determine the thermal stress distribution of functionally graded WC-Co composites. The calculated results show that high stress concentration occurs in the cobalt gradient zone, tensile stress pile-up occurs in the cobalt rich zone and compressive stress pile-up occurs in the surface zone. As the sintering time is increased, compressive residual stress in the surface zone has a tendency of decreasing. The maximum value of compressive stress in the surface zone is 250 MPa. The results are in good agreement with X-ray diffraction measurement results. For the purpose of this work, the material design method is achieved by changing the calculated parameters.

Constitutive Equation for WC-Co Functionally Graded Cemented Carbides and Application

“…The FGCCs was treated as isotropic composites for which the uniaxial stress σ and strain ε are related to the corresponding average uniaxial stress and strain of the two constituent phases as We can obtain the definition of plastic constraint factor as a function of cobalt concentration in Ref. [5]. According to the definition of plastic constraint factor, the initial yield strength of WC-Co alloy, σ 0 is given by…”

“…Here f 1 is cobalt volume fraction as a function of radial position r, σ 01 is the cobalt yield strength varying with the temperature. The parameters 6.25 and -2.99 are obtained by least square fitting [5] . The stress-strain relation of plastic deformation is given by…”

“…Cemented carbides with a functionally graded structure have significantly improved mechanical properties and lifetimes in cutting, drilling and molding, which satisfies the required demand of modern machining technology [1][2][3] . But thermal stresses occur in manufacturing process due to different material properties and components in the surface zone of (FGCC) [4][5][6][7] . The thermal stresses greatly affect the quality, property and lifetime of hard metal productions.…”

Reviews on Modeling of Diffusion-Induced Mass Transportation in Functionally Graded Cemented Carbides

“…A three-zone structure can be typically characterized in this type of FGCC, i.e. a cobalt-deficient zone at the surface with high wear resistance, a cobalt-rich zone in the intermediate region with high toughness, and a carbon-deficient zone in the core with balanced properties [1,[4][5][6][7][8][9][10][11][12]. In the process of fabricating FGCC, the diffusion induced mass-transport is the fundamental process of forming gradient zone.…”

Growth-Induced Stress in Hard Coating

“…To establish advantageous positions within international competitions, investment in research and development is needed and strategic planning must be proposed. Functionally graded cemented carbides with hard coating is an orientation and tendency of development in cemented carbides [1]. To make a breakthrough in key technology is our goal.…”