Characterisation of short fatigue cracks in titanium alloy IMI 834 using X-ray microtomography

被引：47

作者：

Chapman, T. P. ^{[1
]}

Kareh, K. M. ^{[1
]}

Knop, M. ^{[1
]}

Connolley, T. ^{[2
]}

Lee, P. D. ^{[3
]}

Azeem, M. A. ^{[4
]}

Rugg, D. ^{[4
]}

Lindley, T. C. ^{[1
]}

Dye, D. ^{[1
]}

机构：

[1] Univ London Imperial Coll Sci Technol & Med, Royal Sch Mines, Dept Mat, London SW7 2BP, England

[2] Diamond Light Source Ltd, Didcot OX11 0DE, Oxon, England

[3] Univ Manchester, Sch Mat, Manchester M13 9PL, Lancs, England

[4] Rolls Royce Plc, Derby DE24 8BJ, England

来源：

ACTA MATERIALIA | 2015年 / 99卷

基金：

英国工程与自然科学研究理事会;

关键词：

Titanium; Fatigue; Tomography; Vacuum; HIGH-CYCLE FATIGUE; PROPAGATION; TI-6AL-4V; TOMOGRAPHY; DAMAGE; MICROSTRUCTURE; ENVIRONMENT; BEHAVIOR; CLOSURE; GROWTH;

D O I：

10.1016/j.actamat.2015.07.069

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

A first attempt at the three-dimensional evaluation of naturally initiated surface connected and internal fatigue cracks is presented. Fatigue crack initiation and growth in air and vacuum environments have been investigated through X-ray microtomography in air and vacuum environments at elevated temperatures (350 degrees C), accompanied by post-mortem electron microscopy of the fracture surfaces. In vacuum (<10(-5) mbar), multiple internal and surface-connected crack initiation was observed, but only the surface-connected cracks grew. In contrast, fewer cracks formed in air, these were mostly surface-connected and all were observed to grow. In all instances the initiation features were associated with globular primary a. An improved fatigue life was found in vacuum, which was mostly a consequence of delayed initiation, but was also due to slower fatigue crack propagation. The non-propagation of internal cracks was taken to imply that even the good laboratory vacuum obtained here was insufficient to simulate the conditions obtained for an internal crack in a component. The crack shape evolved towards a semi-circular shape a/c = 1 in air during fatigue crack growth, whilst the vacuum cracks remained semi-elliptical (a/c similar or equal to 1.4). This was taken to imply that oxide-induced crack closure played a role in fatigue crack growth in air. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：49 / 62

页数：14

共 33 条

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