真空感应重熔GH3625合金纯净化研究

Purification in Alloy GH3625 Through Vacuum Induction Remelting

为进一步降低GH3625母合金中的氧、氮、硫含量,分别进行了高真空不加钙和高真空加钙2种工艺下的真空感应重熔实验,研究了高真空感应重熔精炼对合金成分和去除杂质元素氧、氮、硫的作用。结果表明:高真空感应重熔元素挥发烧损和富化均控制在标准成分范围;单纯高真空感应重熔时,合金中的氧通过C-O反应脱除,可脱氧至10μg/g,氮分压降低使氮含量脱至70μg/g,但在去硫方面无明显作用;高真空加0.5%钙作净化剂重熔时,Ca-O反应以及Ca与Al_2O_3坩埚内壁反应可实现深度脱氧,通过Ca-S反应使合金中硫含量显著降低,然而氮含量降低程度有限,其含量远高于氮在GH3625合金中的溶解度。采用Al_2O_3坩埚,选择高真空熔炼工艺及适量钙的加入,可使氧、氮、硫含量分别降低到6、60、9μg/g。

For further reduction of oxygen, nitrogen and sulphur contents in master alloy GH3625, two vacuum induction remelting experiments（high vacuum without calcium and high vacuum with calcium addition） were carried out. The effect of vacuum induction remelting purification on the composition and purity of the alloy were investigated. The results show that under high vacuum induction remelting burning loss and enrichment of alloying elements are all in the range of standard composition; deoxidation is excellent under high vacuum induction remelting, and O content is reduced from 17 mg/g to 10 mg/g by C-O reaction; but removal of nitrogen and sulphur is not obvious. During high vacuum induction remelting with 0.5% Ca addition, Ca-O and Ca-Al2O3（the inner wall of crucible） reaction is helpful to deep deoxidation; Ca-S reaction reduces S content greatly, while the decrease in nitrogen content is limited, which is far higher than N solubility in alloy GH3625. In the Al2O3 crucible, high vacuum melting technology with proper calcium addition could reduce oxygen, nitrogen and sulphur contents to6, 60, and 9 mg/g, respectively.