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Creep-fatigue damage evaluation for coated Ni-base superalloys by a.c.potential method.

采用交流电势法评估涂层镍基高温合金的蠕变疲劳损伤。

基本信息

批准号：
07455058
负责人：
OHNAMI Masateru
金额：
$ 4.67万
依托单位：
RITSUMEIKAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455058/
关键词：
High temperature Superalloy Coating material Creep Fatigue Crack Ac potential method Nondestructive test クリープ疲労交流電位差法有限要素法

项目摘要

Creep-fatigue tests were carried out using Inconel 738LC conventional cast and Rene80H directionally solidified Ni-base superalloys. Two strain waves were used in tests. They were fast-fast (pp) and slow-fast waves. The strain rate in fast straining was 0.1/s and that of slow straining 0.001%/s. Fatigue lives in cp tests were compared with those in pp tests and the effect of coating on fatigue life was also discussed. Ac potential method was applied to coated and uncoated specimens for detecting crack damage for the two types of specimens fatigued under pp and cp waves.Fatigue lives under cp wave ware far smaller than those under cp wave for both kinds of specimens. Cracks were initiated at the surface of specimens and propagated into specimens in pp test for coated and uncoated specimens. Cracks were also initiated at the surface of specimens in cp tests for uncoated specimens but they initiated at the intercface between coating and base metal in cp test for coated specimens.The crack damage was monitored for coated and uncoated specimens in pp and tests utilizing the rectangular ac current potential method and FFT analyzer. The potenitial method could detect the cracks initiated at the surface of specimens and at the interface with a sufficient accuracy. Especially, ac potential at low frequencies had a relative high accuracy. The ac potential method was available to the crack detection initiated at the interface between coating and base metal.

对Inconel 738 LC常规铸造镍基高温合金和Rene 80 H定向凝固镍基高温合金进行了蠕变疲劳试验。试验中采用了两种应变波。它们是快-快（pp）和慢-快波。快应变速率为0.1/s，慢应变速率为0.001%/s。比较了CP试验和PP试验的疲劳寿命，并讨论了涂层对疲劳寿命的影响。采用交流电位法对有涂层和无涂层试样进行裂纹损伤检测，发现两种试样在cp波和pp波作用下的疲劳寿命远小于cp波作用下的疲劳寿命。在pp试验中，涂层试样和未涂层试样的裂纹均从试样表面萌生并向试样内部扩展。用矩形交流电位法和FFT分析仪对涂层和未涂层试样的裂纹损伤进行了监测。电位法能以足够的精度检测出试样表面和界面处的裂纹。特别是低频交流电位具有较高的准确度。交流电位法适用于涂层与基体界面裂纹的检测。