"vqw-7~ ELSEVIER Int. J. of Refractory Metals & Hard Materials 15 (1997) 89-98 © 1997 Elsevier Science Limited Printed in Great Britain. All rights reserved 0263-4368/97/$17.00 PII: S0263-4368(96) 00018.2 Structure Sensitivity of Wear Resistance of Hardmetals Heinrich Reshetnyak & Jakob Kiibarsepp Tallinn Technical University, AMP Eesti AS, Tallinn, Estonia (Received 24 October 1995; accepted 18 March 1996) Abstract: The influence of the structure of hardmetals of two classes, tungsten carbide-base cobalt bonded and titanium carbide-base steel bonded, in two dif- ferent wear conditions, erosive and adhesive wear, has been investigated. It has been shown that the wear resistance is much more structure sensitive than any single mechanical property. The structure sensitivity of adhesive wear is much higher than that of erosive and this is related to differences in stress-strain states and fracture mechanics during wear. At equal levels of hardness and approx- imately equal levels of strength, the adhesive wear resistance of TiC-base steel bonded hardmetals (on the contrary to their resistance to erosion) is as good as that of conventional WC-base cobalt bonded hardmetals. © 1997 Elsevier Science Limited 1 INTRODUCTION Hardmetals are mainly used in high speed cut- ting operations when high abrasive wear resist- ance or high diffusion wear resistance are of importance. It is known that hardmetals are effective also as materials for tools of metal forming, particularly for stamping and blanking dies. 1"2 The working conditions of such tools differ substantially from those mentioned earlier: both high wear resistance, in most cases adhesive and sufficient strength-toughness are equally relevant. To choose the most durable hardmetal in a given working condition, the relation between wear resistance and mechanical properties on the one hand and the composition-structure of the hardmetal on the other hand, have to be known. In the present paper the influence of the structure of hardmetals of two classes, tungsten carbide-base cobalt bonded (WC-Co alloys) and titanium carbide-base steel bonded (steel bonded hardmetals -- SBH), in two different wear conditions, erosive and adhesive wear, has been investigated. The content of binder in the alloys, structure, composition and carbide phase grain size were investigated as structural factors. 89 2 MATERIALS AND EXPERIMENTAL DETAILS WC-Co hardmetals with cobalt content 10-20 mass% and an average grain size of carbide phase (1.9-3.3/~m) have been investigated. The WC-Co hardmetals were produced under dif- ferent conditions (carbide carburization tem- perature, sintering temperature and environment). Therefore they differed consider- ably in structure, composition of Co-base binder and mechanical properties, even at equal con- tent of binder. The content of TiC in the TiC-base hard- metals investigated was 40-80 mass%. Different binder structures of SBHs were obtained by alloying and heat treatment. Two of the SBHs were cemented with hardenable martensitic steels; grade TXC with chromium stainless steel (20% Cr) and grade TZC with silicon steel (2% Si). SBHs of grade TXH were cemented with chrome-nickel stainless austenitic steel and those of grade THC with nickel-silicon steel