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采用中频感应炉冶炼了机床滑枕用的QT600-3球墨铸铁,并铸造成不同厚度的试块,采用光学显微镜对试样组织进行了观察,对其拉伸性能和硬度进行了检测。结果表明,随着试块厚度的增加,分布在球墨铸铁基体上的石墨尺寸逐渐增加,数量逐渐减少,形态恶化,逐渐由细小均匀分布的球状转变为团絮状;基体中珠光体含量逐渐减少,铁素体含量增加,当厚度达到100 mm以上时,基体组织中珠光体含量大幅减少,可以得到近乎全铁素体基体的球墨铸铁;抗拉强度和硬度几乎呈线性降低;伸长率则先不变后升高,厚度为100 mm时获得最大值,当厚度进一步增加时伸长率则有所下降。
The medium frequency induction furnace was used to smelt the QT600-3 ductile cast iron used in machine tool ram and cast into test pieces with different thickness. The microstructure of the sample was observed with optical microscope, and its tensile properties and hardness were tested. The results show that with the increase of the thickness of the test piece, the graphite distributed on the ductile iron matrix gradually increases in size, decreases in number and deteriorates in morphology, and gradually changes from a finely-distributed spherical shape to a floc-like shape. The pearlite content in the matrix gradually decreases , The ferrite content increases. When the thickness reaches more than 100 mm, the content of pearlite in the matrix microstructure decreases drastically, and the ductile iron with almost ferrite matrix can be obtained; the tensile strength and hardness decrease almost linearly; while the elongation First unchanged after the increase, the maximum thickness of 100 mm, when the thickness increases further when the elongation decreased.