Título

Solidification and Abrasion Wear Behavior of High Alloyed White Cast Iron

Solidification and Abrasion Wear Behavior of High Alloyed White Cast Iron

Autoria

YU, SUNGKON; SASAGURI, NOBUYA; SINATORA, AMILTON; JR., MARIO BOCCALINI,; MATSUBARA, YASUHIRO

YU, SUNGKON

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SASAGURI, NOBUYA

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SINATORA, AMILTON

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JR., MARIO BOCCALINI,

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MATSUBARA, YASUHIRO

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DOI

10.5151/2594-5327-C01064

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Resumo

Three different white cast irons alloyed with Cr, V, Mo and W were prepared in order to study their solidification and abrasion wear behavior. Melts were super-heated to 1873K(1600°C) in a high frequency induction furnace, and poured at 1823K (1550°C) into Y-block pepest 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), 3%C-10%V-5%Mo-5%W (alloy No. 2) and 3%C-17%Cr-3%V (alloy No. 3). To clarify the solidification sequence, each iron (50g) was remelted at 1723K(1450°C) in an alumina crucible using a silicon carbide resistance furnace under the argon atmosphere. The molten iron was cooled at the rate of 10K/min and quenched into water at several temperatures during thermal analysis. The solidification structures of the specimens were found to consist of primary austenite (γ), (γ+ M7C3) eutectic and (γ+ M6C) eutectic in the alloy No. 1, primary MC, primary austenite (γ), (γ+ MC) eutectic and (γ+ M2C), eutectic in the alloy No. 2 and primary M7C3 and (γ+ M7C3) eutectic in the alloy No. 3, respectively. A scratching type abrasion test was carried out in the states of as-cast (AS), homogenizing (AH), air-hardening AH(F) and tempering AHFT. First, the as-cast specimens were homogenized at 1223K (950°C) for 5h under the vacuum atmosphere. Then, they were air-hardened at 1323K (1050°C) for 2h and followed by tempering at 573K (300°C) for 3h. Abrasion wear test was conducted using the abrasive paper with 120 mesh SiC and 10N (1kgf) application load. The wear loss of the test piece (50x50x5mm) 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 condition in which the alloy No. 3 showed the highest abrasion wear loss. The lowest abrasion wear loss of the specimen No. 2 could be attributed to the fact that it contained primary and eutectic MC carbides as main carbides, which were extremely high hardness. The matrix of each specimen was fully pearlitic in the as-cast state but it was varied by the heat-treated conditions to martensite and retained austenite, which seems to improve the abrasion wear resistance.

Three different white cast irons alloyed with Cr, V, Mo and W were prepared in order to study their solidification and abrasion wear behavior. Melts were super-heated to 1873K(1600°C) in a high frequency induction furnace, and poured at 1823K (1550°C) into Y-block pepest 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), 3%C-10%V-5%Mo-5%W (alloy No. 2) and 3%C-17%Cr-3%V (alloy No. 3). To clarify the solidification sequence, each iron (50g) was remelted at 1723K(1450°C) in an alumina crucible using a silicon carbide resistance furnace under the argon atmosphere. The molten iron was cooled at the rate of 10K/min and quenched into water at several temperatures during thermal analysis. The solidification structures of the specimens were found to consist of primary austenite (γ), (γ+ M7C3) eutectic and (γ+ M6C) eutectic in the alloy No. 1, primary MC, primary austenite (γ), (γ+ MC) eutectic and (γ+ M2C), eutectic in the alloy No. 2 and primary M7C3 and (γ+ M7C3) eutectic in the alloy No. 3, respectively. A scratching type abrasion test was carried out in the states of as-cast (AS), homogenizing (AH), air-hardening AH(F) and tempering AHFT. First, the as-cast specimens were homogenized at 1223K (950°C) for 5h under the vacuum atmosphere. Then, they were air-hardened at 1323K (1050°C) for 2h and followed by tempering at 573K (300°C) for 3h. Abrasion wear test was conducted using the abrasive paper with 120 mesh SiC and 10N (1kgf) application load. The wear loss of the test piece (50x50x5mm) 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 condition in which the alloy No. 3 showed the highest abrasion wear loss. The lowest abrasion wear loss of the specimen No. 2 could be attributed to the fact that it contained primary and eutectic MC carbides as main carbides, which were extremely high hardness. The matrix of each specimen was fully pearlitic in the as-cast state but it was varied by the heat-treated conditions to martensite and retained austenite, which seems to improve the abrasion wear resistance.

Palavras-chave

white cast iron, solidification, abrasive wear

white cast iron, solidification, abrasive wear