不同厚度的数控机床滑枕用球铁组织和力学性能研究

Study on Microstructure and Mechanical Properties of Nodular Cast Iron with Different Thicknesses for CNC Machine Ram

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 QT600-3 nodacar cast iron for machine ram was melted by medium frequency induction furnace, and test blocks with different thicknesses were cast. The microstructure was observed by optical microscope, and the tensile properties and the hardness were measured. The results show that with the increase of block＇s thickness, the graphite size increases and its content reduces gradually. The graphite morphology deteriorates gradually from fine uniformly distributed spheroidal graphite to flocculent graphite. The pearlite content in the matrix reduces gradually, and the ferrite content increases. When the thickness is above 100 mm, the pearlite content in the matrix reduces significantly and the nodular cast iron of almost the whole ferrite matrix can be obtained. The tensile strength and the hardness decrease almost linearly, while the elongation keeps unchanged at first and then increases. When the thickness is 100 mm, the elongation is maximum. While the thickness increases further, the elongation decreases.