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研究了GH4169合金在750℃长期时效中的组织演化及其对低周疲劳行为的影响规律.结果表明,随时效时间的延长,合金中y″相尺寸逐渐增大、体积分数减少;δ相尺寸增大、体积分数增加;长期时效后合金低周疲劳最大循环应力响应降低,疲劳寿命缩短.随循环周次的增加,合金循环应力响应均依次呈循环硬化、稳定、而后软化的特征.合金时效过程中y″相尺寸增大和体积分数降低,导致其对合金的强化效果减弱,由此循环应变的应力响应降低;而时效中长针状d相及其周围的无析出带的生成成为裂纹扩展路径,导致疲劳寿命下降.
The microstructure evolution and its influence on low cycle fatigue behavior of GH4169 alloy at 750 ℃ for long term aging were studied.The results show that with the aging time increasing, the size of y “phase gradually increases and the volume fraction decreases. The δ phase size And the volume fraction of the alloy increases.The maximum cyclic stress response and the fatigue life of the alloy decrease after long-term aging, and the cyclic stress responses of the alloys exhibit cyclic hardening, stable and then softening characteristics with the increase of the number of cycles. During the process, the phase size and the volume fraction of y ”phase decrease, which leads to the weakened strengthening effect on the alloy, and the stress response of the cyclic strain decreases. However, the formation of crack-free zone Path, resulting in decreased fatigue life.