熔模铸造球铁件白口缺陷的形成和预防

Formation and Preventive Measures for Hard Defects in Nodular Iron Castings Produced by Investment Casting Technology

熔模铸造工艺生产中、小型球墨铸铁件产生白口的原因是孕育不足，铸件薄壁处冷却速度较快，V、Cr、Mo等合金元素含量较高。预防措施是用长效硅钡孕育剂进行二次孕育，严格控制化学成分，采用稀土含量较低的球化剂，提高球化处理温度和浇注温度。

In production by using investment casting technology, hard defect producing in small- and medium-sized nodular iron castings stems from insufficient inoculation, excessively rapid cooling of the thin section of castings, and higher contents of vanadium, chromium, and molybdenium. The measures to prevent the hard defect are secondary inoculation with long-term Si-Ba inoculant, strict control of the chemical composition, the use of lower rare earth content spheroidizing agent, the increase in both globularizing temperature and pouring temperature.