Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第27卷    第9期    总第222期    2017年9月

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文章编号:1004-0609(2017)-09-1823-09
GH4742合金疲劳裂纹扩展行为
张宝宁1,袁 超1,郭建亭1,秦鹤勇2,赵光普2

(1. 中国科学院 金属研究所,沈阳 110016; 2. 钢铁研究总院 高温材料研究所,北京 100081)

摘 要: 研究GH4742合金在室温、700 ℃及750 ℃的疲劳裂纹扩展行为。分析温度和应力强度因子对疲劳裂纹扩展寿命与速率的影响,利用扫描电镜观察不同温度下的疲劳裂纹扩展断口。采用背散射电子衍射(EBSD)技术分析合金裂纹扩展的晶体学机制。结果表明,随着温度的升高,合金的裂纹扩展寿命降低,裂纹扩展速率增加,沿晶断裂特征更明显。应力强度因子越大,裂纹扩展速率越大。在原始大变形晶粒中裂纹以穿晶方式沿着小角度晶界扩展,裂纹扩展到再结晶晶界时以沿晶扩展为主,其扩展方式取决于相邻晶粒的面间角和取向差。

 

关键字: 镍基高温合金;疲劳裂纹扩展;断口;微观机制

Fatigue crack growth behavior of GH4742 alloy
ZHANG Bao-ning1, YUAN Chao1, GUO Jian-ting1, QIN He-yong2, ZHAO Guang-pu2

1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China? 2. High Temperature Materials Research Institute, Central Iron and Steel Research Institute, Beijing 100081, China

Abstract:The crack propagation behavior of GH4742 alloy was studied respectively at room temperature, 700 ℃ and 750 ℃. Fatigue fracture was observed by scanning electron microscopy (SEM). Effects of temperature and stress intensity factor (ΔK) on crack growth life and rate were studied. The electron back scattering diffraction (EBSD) technique was applied to investigate the crystallographic mechanism of crack propagation. The results show that with the increase of temperature, crack propagation life of the alloy decreases and crack propagation rate increases as well as the intergranular fracture characteristics is more obvious. Crack growth in the original large deformation grain is in a transgranular manner along a low angle boundary. While crack meets the recrystallized grain boundaries, the mode of fracture is mainly the intergranular expansion and the way of crack growth depends on the magnitude of the interfacial angle and the misorientation of adjacent grain plane.

 

Key words: nickel-based superalloy? fatigue crack growth? fracture; micromechanism

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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