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2 Journal of Achievements in Materials and Manufacturing Engineering

2 2016

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Effect of induction hardening of Fe-C-Ni-Cu-Mo-B metal matrix composites by powder metallurgy for gear production

Gün T., Şimşir M., Özaydin F.

Journal of Achievements in Materials and Manufacturing Engineering

2016

Vol. 79, nr 2

49--53

Purpose: In this study, mechanical behavior of iron base (Fe-0.8 C-2.0 Cu-1.5 Ni-X Mo-Y B (%wt.), x=0.6, 1.2 and 1.8; Y=0.2, 0.6 and 1.0) metal matrix composite (MMC) by powder metallurgy was investigated for gear production. Effect of Mo and B elements on surface hardness, density and microstructure of the composite samples. Design/methodology/approach: MMC has produced by warm compaction method followed by free sintering in controlled Ar gas atmosphere. Green composite has produced under 650 MPa pressure at 160ºC temperature. The green products have been sintered at temperature of 1150ºC and 60 min sintering time. Hardness test have been conducted before and after induction hardening. The microstructure of the samples have been examined before and after induction hardening under optical microscopy. Findings: The results have showed that the highest surface hardness has been obtained X=1.8 and Y=1.0 composition. Addition of Mo and B elements does not affect on the density of the sample. Research limitations/implications: The ability of induction hardening to composite material has been investigated. Originality/value: The studies were carried out in experimental composition with warm compacting method.

Effect of heat treatment on the tensile properties of cam shaft made of ductile cast iron

Karaca B., Şimşir M., Akkan H.

Journal of Achievements in Materials and Manufacturing Engineering

2016

Vol. 76, nr 1

15--20

Purpose: The aim of this study is to investigate effects of austempering heat treatment on the tensile properties of GGG60 ductile cast iron for cam shaft production. For this purpose, cam shafts have been produced by sand casting method. Design/methodology/approach: For nodulizing process, Fe-Si-Mg alloy has been used and Fe-Si-Ba-Ca-Al alloy for inoculation process. The casting has been done between 1410-1420°C and the pouring time was between 11-13 sec. The casted cam shafts and tensile test samples have been austenitized at two different temperatures (800 and 900°C) and time (60 and 90 min.) under controlled furnace atmosphere. The austenitized cam shafts and tensile test samples have been quenched into the molten salt bath at 360°C temperature and held 90 min. and then cooled in air. By this way, austempering heat treatment has been applied. Microstructure of cam shafts and tensile test samples have been examined by optical and scanning electron microscopy (SEM) and mechanical tests (hardness, and tensile tests) have been performed. Findings: Results show that austempering heat treatment increases the tensile strength of cam shaft as-cast condition. Tensile strength of the cam shaft increases with increasing austenitizing temperature and time. The highest tensile strength, 1165.5 MPa, has been obtained from the cam shaft austenitized at 900°C and 90 min. time. Research limitations/implications: The production of cam shafts used in engines, it is carried out with the casting and machining techniques. Today, cam shafts are produced from gray, nodular graphite cast iron, because of many advantages, and also machining of steel.