| The effect of special austempering treatments on the microstructures and mechanical properties of Mo-Cu, Mo-Cu-Ni and Mo-Ni added ADIs(Austempering ductile cast irons) has been investigated. The microstructures of alloys prior to austempering treatment can be changed by introducing the pre-quenched(PQ), pre-heated(PH) or step heated(ST) treatments. The mechanical properties of the Mo-Cu ADI which was austenitized at 900℃ for 2 hours, followed by tempering at 350℃ for 2 hours were superior to those of the Mo-Ni ADI, Mo-Cu-Ni ADIs, and unalloyed ADI. Before austempering treatment, the mechanical properties of ADI can be improved by the control of various prior structures of DCI using a special heat treatment, such as pre-quenched(PQ), pre-heated(PH) or step heated(ST) austempering treatments. The mechanical properties of Mo-Cu ADI were improved by PQ, PH austempering treatment compare to those of other ADIs, therefore PQ Mo-Cu ADI and PH Mo-Cu ADI are expected as promising materials to produce automobile parts in the future. |
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