定向凝固涡轮叶片合金DZ-22的研究

 定向凝固高温合金DZ-22具有较高的中、高温性能,与定向合金PWA1422相当,可用作航空发动机的涡轮叶片材料。它是以PWA1422合金的成分为基础,通过试验对其中铪、碳的含量作了调整。在定向凝固过程中铸型移动速度对零件柱晶的结晶取向有较大的影响。提高固溶处理温度,可明显提高合金的高温持久寿命,但延伸率稍有降低。在固溶处理前进行一次1150℃的预处理,可提高合金的初熔温度。

DIRECTIONALLY SOLIDIFIED BLADE SUPERALLOY DZ-22

The directionally solidified （DS） superalloy DZ-22 possesses rather high mechanical properties at both intermediate and high temperatures, for instance, its stress-rupture strength for 100h at 760℃ and 1040℃ are 804MPaand 139MPa, respectively. Its properties are comparable with the well-known DS superalloy PWA1422. Therefore, it is applicable to advanced aircraft engine blades. The chemical composition of DZ-22 is based on the composition of PWA1422, but the content ranges of Hafnium and Carbon have been readjusted according to experimental results, so its Hafnium content is limited in 1.2-2.0 wt.% instead of 1.5-2.5 wt. % and its Carbon content is 0.12-0.16wt. % rather than 0.08-0.14 wt.%>. In addition, no Zirconium is added intentionally in the alloy. The test results show that the shell-mould with drawn rate during the DS process affects obviously on the orientation of columnar crystals. The suitable drawn rate has been established about 7 mm/min in the equipment of the present work. Enhancement of solution temperature during heat treatment can improve stress-rupture life at both 980℃ and 1040℃, while the elongation decreases slightly. A pretreatment at 1150℃ prior to the solution treatment can raise the incipient melting temperature.