喷丸强化对GH4169合金孔结构高温低周疲劳性能的影响

Effects of Shot Peening on High-temperature Low-cycle Fatigue Property of GH4169 Superalloy with Hole Structure

螺栓结构是航空发动机盘件的重要连接结构,但服役时存在结构应力集中的螺栓孔结构受到大载荷作用,容易发生疲劳失效。根据高压压气机盘螺栓孔结构设计中心孔板材疲劳试样,对中心孔板材疲劳试样进行喷丸强化,研究了原始、高强度和低强度喷丸工艺等3种状态下表面粗糙度和残余应力场,并表征了3种状态下的高温低周疲劳性能。结果表明:相比铰孔状态,大强度的喷丸工艺使孔壁表面粗糙度显著增大,并且在倒角区域出现喷丸塑性流动金属的堆积,虽然引入了深度较大的残余压应力场,但仍然使得疲劳性能有所降低;小强度喷丸后疲劳性能有所提高但分散度增大。通过断口可以看出,原始和小强度喷丸后疲劳源萌生在孔壁处,呈多源疲劳断口;大强度喷丸后疲劳源萌生在孔边倒角区域,为单源断口。

The bolted joint is an important connecting structure of turbine disks; however, there are large loads on the bolt hole with structural stress concentration, leading to the fatigue failure in service. Sheet fatigue specimens with the central hole were designed based on a bolt hole of a high pressure compressor disk, and were shot-peened on two intensi- ties. The surface roughness, residual stress profile and high-temperature low-cycle fatigue property of the three surface integrity statues, such as unpeened, high intensity peening and low intensity peening, were characterized. The results show that： compared with the unpeened sampless, high intensity peening leads to the increase of surface roughness, and the accumulation of plastic-flow metal on the chamfer and the deepening of compressive residual stress, therefore causes the decrease of fatigue performance. On the other hand, when low-intensity peened, fatigue property improves, the dispersion of fatigue lives arises The fatigue crack of unpeened and low-intensity peened specimens is on the wall of the holes, presenting multi-source crack initiations. Moreover, a single fatigue source nucleates on the chamfer when high intensity peened.