DD5合金单晶双联整铸导向叶片的热工艺匹配性

Thermal process matching of single crystal double casting guide vane of DD5 alloy

研究了DD5合金单晶双联整铸导向叶片热工艺顺序对组织和性能的影响。结果表明,DD5合金标准热处理后,合金组织由碳化物、残留共晶相和规则立方状的γ′相组成。与标准热处理相比,时效前后的焊接,碳化物形貌和数量无明显变化,γ′相和基体通道尺寸呈不均匀分布,γ′相的立方化程度降低,可见锯齿状的γ′/γ相界面,基体通道可见细小不规则的二次γ′相。与时效后进行钎焊工艺相比,时效前进行钎焊工艺的γ′/γ相界面锯齿化程度较轻,γ′相的立方化程度稍好,对合金870℃拉伸性能、980℃/250 MPa和1093℃/158 MPa持久性能没有明显影响。考虑到叶片研制生产工序的安排,建议DD5合金导向叶片先进行标准热处理,再安排焊接工序。

Thermal process sequence of single crystal double casting guide vane of DD5 alloy on microstructure and properties was studied. The results show that the microstructure of the DD5 alloy after standard heat treatment is composed of carbides, residual eutectic and regular γ′ phase. Compared with that after standard heat treatment, the morphology and size of carbides welded before or after aging have no obvious change, while the size of γ′ phase and γ matrix channel are not evenly distributed. The cubic shape degree of γ′ phase decreases, the serrated γ′/γ phase interface can be seen, and the fine secondary γ′ phase is precipitated in the γ matrix channel. Compared with that welding after aging, when welding before aging, the serrated degree of γ′/γ phase interface is slight and cubic shape degree of γ′ phase is better, and the tensile properties at 870 ℃, stress rupture properties at 980 ℃/250 MPa and 1093 ℃/158 MPa are not influenced obviously. Considering the process arrangement of vane production, the optimum process sequence of the DD5 alloy guide vane is standard heat treatment first and then welding.