Quasi-Plastic Deformation of WC-Co Composites Loaded with a Spherical Indenter

Abstract

The quasi-plastic deformation behavior of cemented tungsten carbide (WC-Co) materials was studied using Hertzian indentation techniques. The indentation stress-strain curves of three WC-10 wt pct Co alloys with different hardness values demonstrate that WC-Co alloys exhibit ''quasi-plasticity'' behavior under indentation load and the increase of indentation stress vs indentation strain bears similarity to ''strain hardening'' in ductile metals. The analysis of the subsurface indentation damage shows that the mechanisms of the quasi-plastic deformation of WC-Co material are the formation of microcracks. Microcracks were found at heavily damaged areas in all three alloys, and the number of microcracks was higher for the sample with the higher apparent quasi-plasticity. The threshold stress values for the onset of quasi-plastic deformation and formation of ring cracks were determined and used to evaluate the brittleness index of these materials. The correlation of the brittleness index with hardness values gives insight with regard to the brittle or quasi-plastic responses of WC-Co materials.

Quantifying Bulk Plasticity and Predicting Transition Velocities for Armor Ceramics Using Hardness Indentation Tests

“…In general, ceramics are brittle materials that are unable to accommodate significant macroscopic plastic strains. However, examination of indent sites and/or indentation stress-strain behavior in several ceramic materials has shown that they may experience inelastic deformation mechanisms, such as microcracking, microcleavage, slip, and twinning, at room temperature (7,(11)(12)(13)(14)(15)(16)(17). This has led some researchers to propose the use of indentation techniques as a means of "quantifying" quasi-plastic deformation in these materials.…”

Cemented Tungsten Carbide Hardmetal-An Introduction

“…In order to minimize and eliminate the (1979), Bolton and Keely (1982), Sigl, Exner, and Fischmeister (1986), p. 631, Sigl and Exner (1987), Ravichandran (1994), Luyckx, Sacks, and Love (2007), and Zhang, Fang, and Belnap (2007). A. Shatov also further addresses an examination of fracture toughness within this volume in Chapter 1.10.…”

“…Damage evolution has been investigated using a Hertzian indentation technique, which uses a near frictionless spherical indenter loaded normal to a polished surface (Zhang, Fang, et al, 2007). In addition to obtaining stress-strain curves in this work, Zhang measured and evaluated surface and subsurface microscopic and macroscopic cracking.…”

“…In addition to obtaining stress-strain curves in this work, Zhang measured and evaluated surface and subsurface microscopic and macroscopic cracking. The material response was categorized into three regions with increasing stress: a pseudoelastic region with an initial linear stress-strain response; a quasiplastic zone characterized by Co-binder deformation, as well as slip within WC grains and evidence of microcracking; and a fully plastic zone where the stress-strain curve reaches a plateau and the skeleton of interconnected WC grains is broken (Zhang, Fang, et al, 2007).…”

Damage induced by monotonic and cyclic spherical indentation in polycrystalline diamond (PCD)

“…refs. [9][10][11][12][13]). In this study, such protocols are adapted to investigate and document the contact mechanical response of polycrystalline diamond -PCD.…”