采用扫描电镜、显微硬度计、Instron-3382型力学性能试验机等,对双液复合铸造铸件的界面结合情况、微观组织和力学性能进行研究。结果表明：采用合理的铸造生产工艺,成功制备了满足使用性能要求的 HT300/7CrMnSiMoV双金属汽车模具铸件,其复合界面清晰、致密,无明显缩孔、缩松等铸造缺陷；复合界面由钢基体区、过渡区和铁基体区3个区域组成。过渡区呈犬牙状/锯齿形结构,过渡层厚度约为400μm,界面附近Cr和 Si元素呈梯度分布,两种合金冶金结合状态良好；复合界面两侧显微硬度呈梯度分布,其抗拉强度达到339 MPa,断裂位置出现在灰铸铁一侧,双金属界面的结合强度高于灰铸铁。
Interface bonding condition,microstructure and mechanical properties of the bimetal casting prepared by liquid-liquid compound casting were characterized by scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),Instron-3382 tensile testing machine and micro hardness tester.The results showed that HT300/7CrMnSiMoV bimetal steel for automobile cover mold was successfully prepared by reasonable compound casting tech-nology.No microvoid,unbonded region,cracks and other defects were founded at the interface.The composite inter-face was composed of three parts,the steel matrix,the transition region and the iron matrix.The transition region had a zigzag structure with thickness of about 400μm.Cr and Si elements near the interface presented gradient distribu-tion.The two alloys reached a good metallurgical bonding state.The hardness gradually decreased across interface from HT300 to 7CrMnSiMoV and tensile strength of the bimetal reached 339 MPa.Fracture appeared at the side of HT300,and the tensile strength of the bimetal was higher than that of HT300.
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