Investigation of microstructures, mechanical properties, wear behavior and machinability of EN-GJS-500-7 (GGG50) grade ductile cast irons having modified chemical composition

Authors : Mehmet Yıldırım, Hüseyin Gümüş, Mehmet Emin Özcan
Pages : 1143-1149
Doi:10.5505/pajes.2025.79958
View : 54 | Download : 245
Publication Date : 2025-12-15
Article Type : Research Paper
Abstract :Ductile cast irons (DI) are promising candidates for forged steels due to their lower density (10-15 %), lower production cost and good specific strength. The mechanical properties of DIs are heavily influenced by matrix (ferrite, pearlite, or ferrite+pearlite), type and concentration of alloying elements (Si, Cu, Sn, Cr and Ni. etc). The pearlite phase, which is stronger and harder than ferrite phase, depends not only on the chemical composition but also the cooling rate of sections having various section thickness. In this situation non-uniform microstructure and mechanical properties occur between the thick and thin sections of the parts. In this manner solid solution strengthened (with Si) ferritic DIs become prominent with more uniform microstructure and mechanical properties. In the present study, the microstructural properties, mechanical properties (tensile properties, hardness, and impact energy), wear resistance and tool life (turning machining operations) of EN-GJS-500-7 grade ductile cast irons, having modified composition (increased amount of Si, decreased amount of C and pearlite former), are studied in detail. The resultant microstructures and mechanical properties are compared with those for having traditional composition. For modified composition, the ferrite (solid solution strengthened with excess Si) amount considerably increases, and so the cast part exhibits uniform hardness distribution among the surface layer and center regions). In addition, the yield strength and the ultimate tensile strength (UTS) of the modified composition is slightly lower than those for traditional composition. In addition, modified composition exhibits better wear resistance (lower wear loss and friction coefficient) and longer tool life compared to those for traditional composition. As a result, an alloy with improved mechanical properties and good machinability has begun to be applied industrially
Keywords : Küresel grafitli dökme demir, Kimyasal bileşim, Mikroyapı, Mekanik Özellikler, Aşınma Davranışı

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