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为了考察长期时效对GH4586合金动态裂纹扩展的影响,测定了经不同时效时间时效后合金的动态断裂韧性JId。采用光学显微镜、扫描电子显微镜对合金的显微组织及断口形貌进行了分析,探讨了GH4586合金在750℃长期时效过程中合金的组织变化对动态断裂韧性的影响规律。研究表明,GH4586合金经200 h时效后,动态断裂韧性JId从166 N/mm降至86 N/mm,在随后的800 h时效中,动态断裂韧性JId变化不大。时效时合金中的碳化物由在晶界断续析出转变为连续析出,导致了合金的动态断裂韧性降低。而时效500 h后,拓扑密排(TCP)相的析出削弱了晶界碳化物对动态断裂韧性的影响,这是GH4586合金动态断裂韧性变化减缓的主要原因。
In order to investigate the effect of long-term aging on the dynamic crack growth of GH4586 alloy, the dynamic fracture toughness JId of the alloy after different aging time was measured. The microstructure and fracture morphology of the alloy were analyzed by optical microscope and scanning electron microscope. The effect of microstructure and fracture toughness of GH4586 alloy on the dynamic fracture toughness was discussed at 750 ℃ for a long time. The results show that the dynamic fracture toughness (JId) of GH4586 alloy decreases from 166 N / mm to 86 N / mm after 200 h aging, and its dynamic fracture toughness JId does not change much in the subsequent 800 h aging. Aging carbides in the alloy by the intermittent precipitation at the grain boundary into a continuous precipitation, leading to the alloy dynamic fracture toughness decreased. After aging for 500 h, precipitation of topological close-packed (TCP) phase weakens the effect of grain boundary carbides on the dynamic fracture toughness, which is the main reason for the slowing down of the dynamic fracture toughness of GH4586 alloy.