Three-body-type Abrasive Wear Behavior of Multi-alloyed White Cast Iron with Different Carbon Contents Used for Hot Work Rolls

Abstract

In this research, the three-body-type abrasive wear behavior of heat-treated multi-alloyed white cast irons, which has been used for work rolls in hot rolling stands, was investigated. Cast irons with varying C content from 1.73 to 2.34 mass% under 5 mass% of Cr, Mo, W, V each and 2 mass% Co were prepared. After annealing, the specimens were hardened from 1323 K and 1373 K austenitizing by fan air cooling. Hardened specimens (As-H) were tempered at three levels of temperatures which were at maximum tempered hardness (T_HTmax), lower and higher temperatures than that of T_HTmax (L-T_HTmax and H-T_HTmax, respectively). A rubber wheel wear tester was used to evaluate the abrasive wear resistance. It was found that the relationship between wear loss (W_l) and wear distance (W_d) was expressed by a linear function in every wear test. In each heat treatment condition, the wear rate (Rw, mg/m) value decreased as the C content rose. As-H specimens showed almost higher wear resistance than the tempered specimens. In the tempered state, the lowest Rw were mostly obtained in the T_HTmax specimens. The higher austenitizing temperature provided the lower Rw value. The best wear resistance was obtained in the As-H specimen with 2.34%C in the both austenitizing temperatures. The Rw was lowered roughly in proportion to an increase in hardness. However, the Rw values scattered broadly at the volume fraction of retained austenite (Vγ) values lower than 10% and then, decreased gradually as the Vγ value rose, irrespective of austenitizing temperature.