基于表面形貌的裂纹萌生阶段滑移带表征

发布时间：2018-04-21 00:09

本文选题：表面形貌 + 滑移带　；参考：《表面技术》2017年09期

【摘要】：目的研究WaspaloyTM镍基高温合金在裂纹萌生阶段的表面形貌特征,找出最优表面形貌参数用以表征此阶段的滑移带特征。方法对WaspaloyTM镍基高温合金试样先机械抛光,然后采用标准金相技术分别进行电解抛光和化学蚀刻,得到两种不同的表面状态。对试样进行低周疲劳试验获得疲劳寿命,并采用透射电子显微镜(TEM)和三维表面轮廓仪,观测分析WaspaloyTM镍基高温合金在电解抛光和化学蚀刻处理后的表面形貌以及裂纹萌生阶段的表面形貌和滑移带特征。对测得的表面形貌参数进行方差分析和自助抽样统计计算,找出最优参数。结果试样在经过电解抛光和化学蚀刻后,三维表面形貌S_a(表面算数平均偏差)分别是0.72 nm和13.3 nm,试样疲劳寿命分别为800和700。两种制备状态下的样品,算术平均高度增量(ΔS_a=S_a(N)-S_a(N0))的差异非常小,且ΔS_a随疲劳加载周期(N)的增加而增加,当N100后,ΔS_a随N增加的速率减小。结论电解抛光后的表面质量更好,且表面质量越好,疲劳寿命越高。ΔS_a与表面制备方法无关,ΔS_a越大,表面越粗糙。经方差分析和自助抽样法计算分析,表面最大峰值(Sp)是最优表面形貌参数,该参数可用于区分滑移带内的损伤晶粒和未损伤晶粒。
[Abstract]:Aim to study the surface morphology of WaspaloyTM nickel-base superalloy during crack initiation, and to find out the optimal surface morphology parameters to characterize the slip band in this stage. Methods the samples of WaspaloyTM nickel base superalloy were mechanically polished, and then electropolishing and chemical etching were carried out by standard metallography, respectively, and two different surface states were obtained. The fatigue life of the specimen was obtained by low cycle fatigue test. The fatigue life was obtained by means of transmission electron microscope (TEM) and three-dimensional surface profilometer. The surface morphology of WaspaloyTM nickel-base superalloy after electropolishing and chemical etching, as well as the surface morphology and slip band characteristics of the crack initiation stage were observed and analyzed. The analysis of variance and self-help sampling were carried out to find out the optimal parameters of the measured surface topography parameters. Results after electropolishing and chemical etching, the surface morphology of the sample was 0.72 nm and 13.3 nm, respectively. The fatigue life of the sample was 800 and 700 respectively. The difference of the arithmetic average height increment (螖 S _ (a)) of the two kinds of prepared samples is very small, and the 螖 sa _ a increases with the increase of fatigue loading period (N), and the 螖 sa _ a decreases with the increase of N after N _ (100). Conclusion the surface quality after electropolishing is better, and the better the surface quality is, the higher the fatigue life is. 螖 S _ A has nothing to do with the surface preparation method, and the bigger 螖 S _ a is, the rougher the surface is. The analysis of variance and the self-help sampling method show that the maximum peak value of the surface is the optimal surface morphology parameter, which can be used to distinguish the damaged grain from the undamaged grain in the slip band.
【作者单位】：郑州大学机械工程学院;
【基金】：河南省高等学校重点科研项目(15A460030) 国家自然科学基金(51650110502)~~
【分类号】：TG132.3;TG580.692

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