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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/23661

Title: The influence of porosity on the fatigue crack growth behavior of Ti–6Al–4V laser welds
Authors: L. W. Tsay;Y.-P. Shan;Y.-H. Chao;W. Y. Shu
Contributors: NTOU:Institute of Materials Engineering
Date: 2006-11-01
Issue Date: 2011-10-20T08:07:02Z
Publisher: Journal of Materials Science
Abstract: Abstract:The effect of porosity––a common welding defect––on the fatigue crack growth rate (FCGR) in Ti–6Al–4V laser welds was investigated. The experimental results reveal that porosity was present in partial penetration welds over a narrow fusion zone (FZ) with martensite structure. The FCGR of the FZ was lower than that of the base plate. The fracture surface morphology of weld metal was much rougher as compared to that of the base plate. Randomly oriented martensite in the FZ led to local cleavage fracture along a preferred plane, thus, altering the crack growth direction significantly out of the primary crack plane. The zigzag crack path in the FZ resulted in a reduced FCGR at a given ΔK compared to the base plate. Besides, the porous weld showed a serration on the crack growth curve, and behaved the similar crack growth characteristics as the defect free one. SEM fractography revealed that the deflection of crack path around porosity together with local notch blunting as the crack tip pierced into porosity, balanced the increased FCGR for the occurrence of instant crack advance as the crack front reached the porosity at a low stress ratio. In contrast, the serration and drop in FCGR occurred sparingly at a high stress ratio as the crack front met the porosity.
Relation: 41(22), pp.7498-7505
URI: http://ntour.ntou.edu.tw/handle/987654321/23661
Appears in Collections:[材料工程研究所] 期刊論文

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