DD3单晶合金的真空感应熔炼

Vacuum Induction Melting of Single Crystal Superalloy DD3

ＭＣ碳化物、氧化物夹杂和显微疏松在单晶合金中是蠕变、疲劳裂纹的起源和扩展通道。为了减少ＭＣ碳化物、氧化物夹杂和显微疏松的危害，ＤＤ３合金规定：Ｃ≤０．０１０ｗｔ％，最好＜０．００６ｗｔ％，［Ｏ］≤０．００１０ｗｔ％，［Ｎ］≤０．００１２ｗｔ％。合金中脱碳、氧、氮、硫都是通过真空下的Ｃ－Ｏ沸腾反应来完成的。本文采用严格控制碳量和工艺技术的改进等措施，找到了获得Ｃ达６０ｐｐｍ，Ｓ达１０ｐｐｍ，Ｎ＿２达３ｐｐｍ，Ｏ＿２达５ｐｐｍ的ＤＤ３合金的真空感应熔炼的冶金原则。

C crabides, oxide inclusions and microporosities in single crystal superalloys are the crack sourcesand crack propagation paths of creep and fatigue. In order to reduce detrimental influence of MC car-bides,oxide inclusions and microporocities ,it is defined that [C]≤0.010wt%(it will be better,when[C]≤0. 006wt%),[O]≤0.001wt%,[N]≤0.0012wt%in the single crystal superalloy DD3.Allthe decarbenization,deoXidation,denitrogenation and desulphurization are camed out through CO rcactionwith ebullition.The propor vacuum induction melting process has been obtained for preducing the single crystal suporalloy DD3 in which[C]≈60ppm,[S]≈10ppm,[N]≈3ppm and[O]≈5ppm by strictly controlling the content of the carben and improving the technique.