GH4169高温合金的疲劳行为研究

Study on fatigue behavior of GH4169 superalloy

对GH4169高温合金在低周疲劳和高低周复合疲劳条件下的微观组织演变、疲劳寿命以及断口形貌进行了系统研究。通过MTS809疲劳试验机对材料进行疲劳实验,并利用扫描电子显微镜(scanning electron microscope,SEM)和电子背向散射衍射(electron back-scattered diffraction,EBSD)对疲劳断口及微观组织进行分析。结果表明:在低周和高低周复合疲劳条件下,裂纹主要萌生于材料的表面,并沿着滑移带和晶界扩展;两种疲劳条件下的疲劳断口均表现出韧窝结构,其中高低周复合疲劳条件下的韧窝更为显著;碳化物夹杂是韧窝形核的重要位置;疲劳加载过程中形成的大量小角度晶界可能是导致韧窝形成的主要原因。

A systematic study was conducted on the microstructural evolution,fatigue life,and fracture morphology of GH4169 superalloy under low-cycle fatigue and combined high and low cycle fatigue conditions.The material was subjected to fatigue testing using an MTS809 fatigue testing machine,and the fatigue fracture surfaces and microstructures were analyzed in detail using a scanning electron microscope(SEM)and electron backscatter diffraction(EBSD).The results indicate that under low cycle fatigue and high and low cycle fatigue conditions,cracks mainly originate on the surface of the material and propagate along slip bands and grain boundaries.The fatigue fracture surfaces under the two fatigue conditions exhibit dimple structures,with dimples being more pronounced under high and low cycle fatigue conditions.Carbide inclusions are important locations for dimple nucleation.The large number of small angle grain boundaries formed during fatigue loading may be the main reason for the formation of ductile dimples.