Effect of Cu-Ni and Cu-Ni-Mn on the Microstructural and Mechanical Behaviour of As-Cast Non-Inoculated Hypereutectic Grey Iron  

作　　者：Seidu Ojo[1] Adama Sumaila[1] Onigbajumo Adetunji[1] 

出　　处：《Journal of Minerals and Materials Characterization and Engineering》2020年第2期27-46,共20页矿物质和材料特性和工程（英文）

摘　　要：The hypereutectic region of grey cast iron has received very little attention especially for designing cast products by researchers. Due to its high carbon equivalence, hypereutectic grey iron poses some challenges especially its tendency for grey to white transition (GWT) at this level of carbon content. However, hypereutectic grey iron possesses inherent properties that could be easily utilized for improved performance in automobile engines and brake pad system. Significantly, they could be modified for superior hardness, strength and toughness. This study presents the effect of microalloying on the mechanical behaviour of hypereutectic grey cast iron with carbon equivalence above 4.5. The first part of this work presented in this paper considers the addition of Cu-Ni and Cu-Ni-Mn to series of as-cast hypereutectic grey cast iron and their hardness and tensile strength were studied and compared. A total of 33 cast samples were obtained with the control sample. The examination of the micrographs revealed that graphite eutectics cells of Type A and A + D were obtained in the resulting microstructure. Results analyses showed that the ferrite forming tendency of silicon was suppressed due to the high carbon content of the as-cast hypereutectic grey iron coupled with the absence of inoculation which plays a great role in the graphite flake type, network, size and distribution. Cu-Ni microalloying was also confirmed to promote hardness with the hardening effect limit of nickel observed at 1.3% composition. For Cu-Mi-Mn addition, excess and free sulphur in the hyper- eutectic grey iron results in reverse effect of manganese on strength, hardness, reduced graphite flake size and shape.The hypereutectic region of grey cast iron has received very little attention especially for designing cast products by researchers. Due to its high carbon equivalence, hypereutectic grey iron poses some challenges especially its tendency for grey to white transition (GWT) at this level of carbon content. However, hypereutectic grey iron possesses inherent properties that could be easily utilized for improved performance in automobile engines and brake pad system. Significantly, they could be modified for superior hardness, strength and toughness. This study presents the effect of microalloying on the mechanical behaviour of hypereutectic grey cast iron with carbon equivalence above 4.5. The first part of this work presented in this paper considers the addition of Cu-Ni and Cu-Ni-Mn to series of as-cast hypereutectic grey cast iron and their hardness and tensile strength were studied and compared. A total of 33 cast samples were obtained with the control sample. The examination of the micrographs revealed that graphite eutectics cells of Type A and A + D were obtained in the resulting microstructure. Results analyses showed that the ferrite forming tendency of silicon was suppressed due to the high carbon content of the as-cast hypereutectic grey iron coupled with the absence of inoculation which plays a great role in the graphite flake type, network, size and distribution. Cu-Ni microalloying was also confirmed to promote hardness with the hardening effect limit of nickel observed at 1.3% composition. For Cu-Mi-Mn addition, excess and free sulphur in the hyper- eutectic grey iron results in reverse effect of manganese on strength, hardness, reduced graphite flake size and shape.

关 键 词：HYPEREUTECTIC Grey IRON Microstructure Hardness Tensile Strength Inoculation GRAPHITIZATION Cast IRON ALLOYING 

分 类 号：TG1[金属学及工艺—金属学]