精炼及破空对镍基合金中氧氮含量的影响

Influence of Refining and Vacuum-Breaking on Oxygen and Nitrogen Contents in Ni-Based Superalloy

采用真空感应法熔炼镍基合金,测定了精炼后合金的氧、氮含量,并观察合金中的夹杂情况。研究了精炼、破空处理对合金中氧、氮含量及夹杂的影响。结果表明:真空感应熔炼镍基高温合金在精炼的初始阶段,氧的脱除速率较大,主要通过氧与碳的还原反应生成CO气体进行;精炼后期氧元素的脱除速率有所降低。合金中氮元素的排除主要依赖高温和高真空作用,氮元素排除速率受CO的生成和排出影响。合金中的氧、氮含量与合金中的夹杂含量相关,精炼期间合金中的Al2O3夹杂与高温液态金属中的氧元素之间存在动态平衡,随精炼时间延长合金中Al2O3夹杂分解,合金中夹杂含量及氧、氮含量均降低。

After refinement,oxygen,nitrogen and inclusions contents of the Ni-based superalloy melted by vacuum induction were determined.The influences of the refinement and vacuum-breaking on the O,N contents and inclusions were researched.The results show that at the initial stage of refinement the oxygen reacts with carbon and produces CO,the degassing rate of the oxygen is high,but decreases at later stage.The degassing of nitrogen relies on the high temperature and vacuum.The degassing rate of the nitrogen is affected by the rate of CO＇s production and discharging.The O,N contents are related to the inclusion content in the alloy.There is a dynamic balance between element O in liquid metal and Al2O3 inclusion at high temperature during refining.The contents of oxygen,nitrogen and inclusions are all reduced and the Al2O3 inclusions in the alloy are decomposed with the refining time prolonged.