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制备了壁厚呈阶梯状的薄壁球墨铸铁件,研究了不同真空保压时间对薄壁球墨铸铁组织及石墨形貌的影响。结果表明,球墨铸铁合金熔体经过合适时间的真空保压,能够有效提高组织中的石墨数量,消除组织中分布的较大尺寸石墨。对于壁厚为2 mm的铸件,真空保压3 min后,组织性能最优。阶梯状铸件中不同壁厚部位中的珠光体率对熔体中的熔存含氧量的敏感度不同。熔体经真空保压3 min后,壁厚为4 mm和6 mm部位的珠光体率下降16%,而薄壁2 mm的部位珠光体率基本不变。
The thin walled ductile iron with stepped wall thickness was prepared. The effect of different vacuum dwell time on the microstructure and graphite morphology of the thin walled nodular cast iron was studied. The results show that the ductile iron alloy melt under vacuum pressure for a suitable time can effectively increase the amount of graphite in the tissue and eliminate the larger size graphite distributed in the tissue. For castings with a wall thickness of 2 mm, the tissue properties are optimal after 3 minutes of vacuum packing. The sensitivity of the pearlite fraction in different wall thickness fractions to the molten oxygen content in the melt is different for the stepped casting. Melt vacuum pressure 3 min, the wall thickness of 4 mm and 6 mm parts of the pearlite rate decreased 16%, while the thin-walled 2 mm pearlite body rate remained unchanged.