碳对高温合金DZ417G定向凝固组织及持久性能的影响规律

Effect of Carbon on the Microstructure and Rupture Properties of DZ417G during Directionally Solidified of Ni-based Superalloy

采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)等方法研究了3种不同碳含量的DZ417G高温合金的凝固组织、热处理组织和持久性能,分析了合金显微组织和持久性能之间的关系。结果表明:随着C含量的增加,合金中的共晶数量减少,MC碳化物数量增多。经过热处理后,枝晶干的γ'相呈均匀细小的立方块状,且枝晶间的共晶及粗大的γ'相基本回溶,达到了较好的均匀化效果;MC碳化物发生了退化反应,出现了M23C6碳化物。随着C含量增加,合金的持久寿命减小,这是因为合金中未消除的共晶、碳化物及缩松会成为合金性能的薄弱位置,而C会直接引起合金中的共晶及碳化物数量的变化,因此,认为含碳量为0.05wt.%时,合金的持久性能最佳。

The effects of carbon addition on the solidification microstructure and heat treat-ment microstructure and rupture life were investigated in three different carbon level of DZ417 G superalloys through scanning electron microscopy （SEM ）and transmission elec-tron microscopy （TEM）. The relationship between microstructure and rupture property was discussed. The results showed that with the increasing of carbon level,the volume fraction of eutectic decreased and the volume fraction of carbides increased. After heat treatment theγ′become uniform cubical and theγ-γ′eutectic were dissolved mainly;MC carbides were dis-solved slightly,and M23 C6 appeared after heat treatment. With the increasing of carbon addi-tion,the rupture life of the DZ417G superalloy decreased. The change of rupture life was mainly affected by the un-dissolved eutectic and carbides of alloy. The volume of eutectic and carbides were controlled by carbon addition,therefore,the carbon content should be＆amp;nbsp;controlled in 0. 05wt.%,which was benefit to the rupture property mostly.