DZ125高温合金超高周疲劳裂纹萌生与扩展

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2014年12月 第9卷第6期 失效分析与预防 December,2014 

Vo1.9。No.6 

DZ125高温合金超高周疲劳裂纹萌生与扩展 顾玉丽 ,陶春虎 ,佘力 ,何玉怀 ,许罗鹏 (1.北京航空材料研究院,北京100095;2.航空材料检测与评价北京市重点实验室,北京100095; 3.中航工业失效分析中心,北京100095;4.四川大学空天科学与工程学院,成都610064) 

[摘要]裂纹的萌生与扩展是研究合金材料超高周疲劳行为的重要方面。本研究分析与探讨了温度和表面状态对DZ125 合金的超高周疲劳裂纹萌生与扩展特征的影响。不同温度下,DZ125合金的超高周疲劳裂纹萌生位置和扩展方式不同。室 温下,裂纹均沿表面起源,裂纹扩展以拉伸模式为主;700 下,裂纹均沿亚表面起源,裂纹扩展以剪切模式为主。室温下, DZ125合金经激光冲击处理前后的超高周疲劳裂纹萌生位置和扩展方式均存在差异。经过激光冲击处理后,裂纹萌生于合 金的内部孔洞缺陷,裂纹扩展完全以剪切模式进行。 【关键词]镍基铸造高温合金;超高周疲劳;裂纹萌生;裂纹扩展 [中图分类号]TG132.3 [文献标志码]A doi:10.3969/j.issn.1673 ̄214.2014.06.001 [文章编号]1673 ̄214(2014)06-0323-07 

Analysis on Ultra-high Cycle Fatigue Crack Initiation and Propagation Characteristics 0f DZ125 Superalloy GU Yu.1i , ,。,TAO Chun.hu , ’ ,SHE Li ,HE Yu—huai , '。,XU Luo.peng 

(1.Be ng Institute ofAeronautical Materials,Beijing 100095,China; 2.Beijing Key Laboratory of Aeronautical Materials Testing and Evaluation,Be ng 100095,China; 3.AvieFailure 砌Zy is Center,Beijing 100095,China; 4.School ofAeronautics and Astronautics,Sichuan University,Chengdu 610064,China) Abstract:Crack initiation and propagation are important aspects of studying ultra—high cycle fatigue behavior of DZ125 superalloy.The analysis and discussion were carried on the effect of the temperature and surface status on the uhra—high cycle fatigue crack initiation and propagation character of DZ125 superalloy.The uhra—high cycle fatigue crack initiation position and propagation pattern of DZ125 superalloy vary with temperatures.All fatigue cracks initiated from the surface and propagated mainly in the tensile pattern at room temperature.All fatigue cracks initiated from the subsurface and propagated mainly in the shear pattern at 700℃.The ultra-high cycle fatigue crack initiation position and propagation pattern were different for DZ125 superalloy before and after laser shock processing at room temperature.The fatigue crack initiated from the cavities within the DZ125 superalloy and propagated entirely in the shear pattern. Key words:cast Ni-base superalloy;ultra—high cycle fatigue;crack initiation;crack propagation 

0 引言 通常,合金材料的超高周疲劳裂纹的萌生和扩 展,呈现出与低周和高周疲劳不同的特有过程,是 研究合金材料超高周疲劳行为的重要方面。大量 的研究结果显示,超高周疲劳裂纹的内部萌生和表 面萌生对应着不同的疲劳寿命。在高周疲劳阶段, 

裂纹在表面萌生,而在超高周疲劳阶段(循环周次 >10 ),裂纹可能会从表面转入内部萌生,也可能 还在表面,这与合金的种类、夹杂物、缺陷的大小、 残余应力等因素相关 。 。如果疲劳裂纹萌生于合 金内部,断口源区的“鱼眼”是高强度钢的典型特 征 J,裂纹扩展的主要阶段集中在“鱼眼”的内 部。对于无明显缺陷的材质,裂纹一般萌生于大晶 粒、相界面、孪晶等组织不均匀处 j。 

【收稿日期]2014年9月25日 【修订日期]2014年l1月21日 [基金项目]国家自然科学基金(11302212);中国民航飞行学院开放基金项目(F2014KF01) [作者简介]顾玉丽(1979年一),女,博士,高级工程师,主要从事材料的结构损伤分析等方面的研究。 第6期 顾玉丽,陶春虎,佘力,等:DZ125高温合金超高周疲劳裂纹萌生与扩展 329 4)室温下,DZ125合金经过激光冲击处理后 的超高周疲劳断口均显示与应力轴成45。的剪切 断裂模式,裂纹萌生于合金的内部孔洞缺陷。 5)长期时效状态(950 cC,1 500 h)的DZ125 合金,经过激光冲击处理后,原来的球形 相有 了较大幅度的改善, 相正方度略有提高,出现定 向排列现象。 

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