Inconel 625合金的室温低周疲劳与断裂行为

Low cycle fatigue and fracture behavior of Inconel 625 alloy at room temperature

为了对Inconel 625合金构件的抗疲劳设计提供可靠的理论依据,在室温下对Inconel 625合金进行了轴向总应变幅控制的低周疲劳实验,分析了室温下合金的应变疲劳寿命和循环应力应变数据,进而给出了合金的应变疲劳参数.采用扫描电子显微镜和透射电子显微镜对Inconel 625合金试样进行了断口形貌分析和微观组织观察.结果表明,Inconel 625合金在室温下的弹性应变幅和塑性应变幅与载荷反向周次的关系可分别用Basquin和Coffin-Manson公式来描述.在室温疲劳变形过程中,Inconel 625合金会发生循环硬化和循环软化.合金的低周疲劳裂纹以穿晶方式萌生于疲劳试样的自由表面,并以穿晶方式扩展.

In order to provide a reliable theoretical basis for the fatigue-resistant design of Inconel 625 alloy components, the axial total strain amplitude-controlled low-cycle fatigue tests were performed for Inconel 625 alloy at room temperature. In addition, the strain fatigue life and cyclic stress-strain data at room temperature were analyzed to determine the strain fatigue parameters of the alloy. The morphology analysis for fracture surfaces and microstructural observation were performed for the Inconel alloy specimens with scanning electron microscope （SEM） and transmission electron microscope （TEM）, respectively. The results show that the relationship between both elastic and plastic strain amplitudes as well as reversals to failure for the alloy at room temperature can be described by Basquin and Coffin-Manson equations, respectively. It is noted that the Inconel 625 alloy exhibits the cyclic strain hardening and softening during the fatigue deformation at roon temperature. For the Inconel 625 alloy, the low-cycle fatigue cracks transgranularly initiate on the free surfaces of fatigue specimens and propagate in a transgranular mode.