| Three different white cast irons alloyed with Cr, V, Mo and W were prepared in order to study their abrasion wear behavior in as-cast and heat-treated conditions. The specimens were produced using a 15㎏-capacity high frequency induction furnace. Melts were super-heated to 1600℃, and poured at 1550℃ into Y-block pepset molds. Three combinations of the alloying elements were selected so as to obtain the different types of carbides : 3%C-10%Cr-5%Mo-5%W(alloy No. 1: M_7C₃ and M_6C), 3%C -10%V-5%Mo-5%W(alloy No. 2: MC and M₂C) and 3%C-17%Cr-3%V(alloy No. 3: M_7C₃only). A scratching type abrasion test was carried out in the states of as-cast(AS), homogenizing(AH), air-hardening(AHF) and tempering(AHFT). First of all, the as-cast specimens were homogenized at 950℃ for 5h under the vacuum atmosphere. Then, they were austenitized at 1050℃ for 2h and followed by air-hardening in air. The air-hardened specimens were tempered at 300℃ for 3h. 1㎏ load was applied in order to contact the specimen with abrading wheel which was wound by 120 mesh SiC paper. The wear loss of the test piece(dimension: 50×50×5㎜) was measured after one cycle of wear test and this procedure was repeated up to 8 cycles. In all the specimens, the abrasion wear loss was found to decrease in the order of AH, AS, AHFT and AHF states. Abrasion wear loss was lowest in the alloy No. 2 and highest in the alloy No. 1 except for the as-cast and homogenized condition in which the alloy No. 3 showed the highest abrasion wear loss. The lowest abrasion wear loss of the alloy No. 2 could be attributed to the fact that it contained primary and eutectic MC carbides, and eutectic M₂C carbide with extremely high hardness. The matrix of each specimen was fully pearlitic in the as-cast state but it was transformed to martensite, tempered martensite and austenite depending upon the type of heat-treatment. From these results, it becomes clear that MC carbide is a significant phase to improve the abrasion wear resistance. |
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16402105.pdf 
