气体含量及熔体热处理温度对K465高温合金初生MC碳化物形态的影响

采用真空熔炼炉,在不同熔体热处理温度下精炼K465合金,然后浇注持久性能试棒,分析气体含量和熔体热处理温度对K465合金初生MC碳化物形态的影响.结果表明,MC碳化物形态与合金熔体中氧和氮的总量即气体含量有关.在同一温度下,随着气体含量的增加,MC碳化物由骨架状经小颗粒+短杆状演变成颗粒状.氮和氧影响MC碳化物析出形态的方式不同,熔体中的氮通过形成MC碳化物的形核核心来影响MC碳化物的析出形态,而氧则是通过改变氮在熔体中的存在形式影响MC碳化物的析出形态.提高熔体热处理温度可以增大初生MC碳化物以颗粒状形态析出的趋势,但相比于气体含量其影响较小.

Influence of Gas Content and Temperature of Melt Heat Treatment on Primary MC Carbide Morphology of K465 Superalloy

The K465 alloy was refined at different melt heat treatment temperature in vacuum melting furnace,and test bars were poured.The effect of gas content and melt heat treatment temperature on primary MC carbide morphology of K465 alloy was investigated.The results show that primary MC carbide morphology changed with the gas content,which includes O and N.At the same temperature,primary MC carbide morphology changed from skeleton to granular shape with increase of gas content.The effect of O on the precipitation morphology of primary MC carbide was different from that of N.N through the formation of TiN or Ti(C,N) acted as the nucleation site of MC carbide which affected the precipitation morphology of primary MC carbide,while O can reduce the dissolvability of N in melt and promote the formation of TiN or Ti(C,N).The trend of MC carbide morphology changing from skeleton to granular shape increased with increase of melt heat treatment temperature.