Properties and Testing of Cemented Carbides

Abstract

This chapter deals with selected properties of cemented carbides and their testing. It consists of three main sub-chapters. The first one covers the degradation processes associated with grinding of cemented carbides. Among those, the focus is on the effects of thermal loads and reactions with the environment-the atmosphere. The second main sub-chapter describes the origin of residual stresses and their impact on cemented carbide properties. Finally, the third main sub-chapter explores the corrosion of cemented carbides in various environments. The choice of these topics was inspired by the impression that many users have of cemented carbides: indestructible materials in which no degradation takes place either during the production of cutting tools or during their use. As evidenced by the authors' experience described below, which has been acquired over many years in the field, damage in cemented carbides is a very frequent occurrence. Despite that it still receives very little attention, and especially the damage in cemented carbide cutting tools tends to be ascribed to various other factors, such as the applied coatings, the cutting process conditions and the material of the workpiece.

Development of the Structure of Cemented Carbides during Their Processing by SLM and HIP

“…The typical resulting microstructure of a cemented carbide consists of hard WC carbide particles (α-phase), tough metallic binder of Co (β-phase) and certain other carbides (γ-phase) with tetragonal crystal structure. These constituents and their size and amount in the structure govern the mechanical and physical properties of CC and its intended use [1][2][3][4][5].…”

Degradation of Sintered Carbides in Different Corrosive Environments

“…4. The process of sample degradation in sulphuric acid solution can then be described by equations (4), ( 5) and (6). [3], [7], [10] These equations describe the interaction of elements of the binder with elements of the degradation media.…”

“…Despite the adaptation of the WC-Co structure to these applications, this material will be degraded either by mechanical stress, for example by abrasion during machining, or by its interaction with solutions that may contain soils or acid solutions when they are used in the mining industry. [6], [11], [14] This article deals with one type of degradation process of sintered carbides which is caused by the chemical activity of the environment which affects the corrosion resistance of sintered carbides. One of the main objectives of the experiment was to verify the corrosion resistance of the sintered carbides during their long exposure in selected corrosive environments.…”

“…Research has shown [1], [2], [3], [4], [5], [6], [8], [9], [10], [12], [14] that corrosion resistance of cemented carbides is primarily dependent on the chemical purity of the binder and its chemical composition. Corrosion of cemented carbides occurs because tungsten carbide grains and the binder form a galvanic cell where the environment creates an electrolyte.…”