Influence of reinforcement volume fraction and size on the microstructure and abrasion wear resistance of hot Isostatic pressed white iron matrix composites

Abstract

The changes in the microstructure and wear resistance of a powder metallurgical high-Cr white iron after the incorporation of TiC particles were studied in the present work. Various reinforcement volume fractions and sizes were used in order to examine their influence on the three-body abrasion wear resistance. The experiments were carried out at three different austenitizing temperatures. The most important observation after a microstructural examination was the increased amount of martensite in the composites subjected to identical heat treatment procedures with the unreinforced alloy. The austenite-to-martensite transformation in the composites increased with the TiC volume fraction and with the austenitizing temperature. This indicates that the two parameters have a key role in the transformation mechanism, which seems to be mechanically induced. The increasing of martensitic transformation with the TiC content in the composites enhanced continuously the supporting ability of the iron alloy matrix to the TiC particles, which in turn increased the wear resistance of the composites. The abrasion wear resistance increased with the TiC volume fraction until the onset of spalling. However, in composites containing coarse reinforcements, spalling occurred earlier in the wear process. This decreased wear resistance significantly because spalled TiC particles contributed additionally to wear.