WEAR OF TAC AND TIC STEEL COMPOSITE HARDFACINGS BY SOFT AND HARD ABRASIVES

TiC and TaC steel composite layers were produced on a die steel 90MnCrV8 (0.9% C) by using a CO2-laser. The hard particles of a median size of 3 mu, and 30 mum, respectively, and a volume fraction of about 50% were homogeneously distributed in the steel matrix. Hardness of the martensitic matrix was variied by heat treatments. Wear resistance of the hardfacings against flint and SiC with varying mesh sizes were measured using an abrasive wear tester at laboratory atmosphere. Abrasive wear resistance was increased by more than one magnitude of order by embedding the hard phases in the steel surface. The results showed the effects of type and size of the hard phase, hardness of the steel matrix and also of the type and mesh size of abrasive grits on wear resistance. Experimental results are discussed as a function of those parameters and theoretical models are developed.