奥氏体球铁阀杆螺母覆膜砂铸造工艺

Coated Sand Technique for Austenitic Ductile Cast Iron Stem Nut

合理设计工装、浇注系统,采用覆膜砂制型壳,透气性好,浇注高镍奥氏体球铁阀杆螺母,达到精铸效果,生产成本低。熔炼时控制好化学成分,用QRMg7特制球化剂球化处理,75硅铁加锡、加铋孕育有利于提高球化率、塑性。热处理用1040℃以上高温正火,快速冷却可大幅度提高强度、伸长率。

The fixture and the gating system were reasonably designed in the production of austenitic ductile cast iron stem nut, using coated sand to produce shell mould with good permeability. The stem nut castings of high Ni austenitic ductile cast iron can be achieved with the effect of precision casting and low production cost, properly controlling chemical composition in melting, using QRMg7 special spheroidizing agent, FeSi75 inoculation with Sn and Bi which helps to improve spheroidizing rate and ductility, using heat treatment of normalizing at 1040℃ and above, fast cooling to improve strength and elongation.