单晶高温合金DD6的中温横向持久性能

Transverse Stress-rupture Properties of Single Crystal Superalloy DD6 at Mediate Temperature

在800,850,900℃的温度条件下,对第二代单晶高温合金DD6的横向持久性能进行了研究。结果表明:与相同条件下的纵向即[001]取向持久性能相比,合金横向持久寿命低于纵向持久寿命。在相对较高温度下,合金横向与纵向的持久寿命在数值上相差较小;在相对较低温度下,合金横向持久寿命明显低于纵向。随着实验温度的升高,扩散蠕变作用增强,韧窝断裂的倾向增加,同时枝晶间和枝晶干变形均匀,横向持久性能相对提高而接近于纵向持久性能。垂直于应力轴的一次枝晶界和枝晶间区域的存在,是横向持久性能低于[001]取向的主要原因。

The transverse stress-rupture properties of the second generation single crystal superalloy DD6 were investigated at 800, 850, 900℃. The results show that the transverse stress-rupture lives are less than the longitudinal, i.e. the [001]-oriented. At relatively higher temperatures, the trans- verse stress-rupture lives approach quantitatively to the longitudinal, while at relatively lower temperature the transverse stress-rupture lives are obviously less than the longitudinal. With temperature in- creasing, the diffusion has more effects on the creep of the alloy, as makes the deformation between dendrite cores and interdenditic regions uniform so that the transverse stress-rupture properties relatively increase and approach to the longituadinal. That the transverse stress-rupture properties are inferior to the [-001]-oriented results mainly from the primary dendrite interfaces and interdendritic regions, which are perpendicular to stress axis and must sustain the full load.