Thesis (M.Eng.)--Chulalongkorn University, 2011

Hypoeutectic 26 wt% Cr cast irons without and with Mo were prepared in order to investigate their abrasion wear resistance. The annealed specimens were hardened from 1323 K and then tempered at three levels of temperatures between 673 and 823 K for 7.2 ks, the temperature giving the maximum hardness (HTmax), temperature lower than that at HTmax (L-HTmax ) and temperature higher than that at HTmax (H-HTmax). The abrasive wear resistance was evaluated using Suga abrasion wear test (two-body-type) and Rubber Wheel abrasion wear test (three-body-type). It was found that hardness and volume fraction of retained austenite (Vγ) in the heat-treated specimens varied by the Mo content and the heat treatment condition. A linear relation was obtained between wear loss and wear distance in all specimens. The lowest wear rate (Rw) was obtained in both the As-hardened and the HTmax specimens. The highest Rw was obtained in both the L-HTmax and the H-HTmax specimens. Rw decreased with increasing hardness. In Suga abrasion wear test, the lowest Rw obtained in the specimens with around 10% Vγ. The Rw decreased with an increase in Mo content. In Rubber Wheel abrasion wear test, the lowest Rw obtained also in the specimen with 10% Vγ. However, the Rw was independent on Mo content.