镍基单晶气膜孔模拟试样的低周疲劳断裂机理

Low Cycle Fatigue Fracture Mechanism of a Modeling Specimen with Cooling Film Hole of DD6 Single Crystal Superalloy

摘要:

采用镍基单晶合金DD6带不同数量激光加工气膜孔的薄壁平板模拟试样，对其在900 ℃下的低周疲劳性能进行了研究，并对试验数据和断口的SEM形貌进行了分析。结果表明：在相同的试验条件下，气膜孔的数量对低周疲劳的寿命影响很大，单孔试样的寿命约为密排多孔试样的10倍；气膜孔周围存在大量微裂纹，带气膜孔试样的破坏属于典型的多源断裂；对于单孔试样及密排多孔试样的中间孔，裂纹沿{001}面扩展；密排多孔试样的上下2排气膜孔周围的裂纹沿多个滑移面扩展。

Abstract:

The flat plate specimens of nickel-base single crystal superalloy DD6 with different numbers of laser-processed cooling film holes were used to study the low cycle fatigue properties at 900 oC. The test data and SEM fracture images were analyzed. The results show that the life of single-hole specimens is ten times of that of the close-spaced holes specimens in the same experimental condition. A number of microcracks are found around the cooling film hole and the destruction of the specimens with cooling film holes is a typical multi-source rupture. The cracks propagate along the {001} planes for single-hole specimens and the middle holes of the close-spaced holes specimens, but the cracks extend along a plurality of slip plane for up and bottom holes of the specimens with close-spaced holes.