Influence of As-Cast Microstructure on the Impact Wear Resistance of 27 mass%Cr Cast Iron

The impact wear resistance of 27 mass%Cr cast iron which as-cast microstructure influenced by cooling rate during solidification was investigated by using abrasive blasting machine. Hardness and volume fraction of martensite of samples with and without contacting with an iron chiller were measured before and after abrasive blasting test. Refinement of microstructure which was due to increase of cooling rate gave adverse effect on the impact wear resistance. Through impact of abrasive media on the surface, austenite in matrix was easy to transform into martensite, and it was obvious that there were much more micro-cracks in carbide and boundary of carbide and matrix. As volume of martensite increased, the abrasion occurred remarkably. This is explained by impingement heat generated which causes self-temper softening of martensite occur during abrasive blasting test.