期刊
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
卷 517, 期 1-2, 页码 334-343出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2009.04.051
关键词
Magnesium alloy; Cyclic deformation; Low cycle fatigue life; Strain ratio; Strain rate
类别
资金
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- AUT021 Network of Centres of Excellence
- Canada-China-USA Collaborative Research Project on the Magnesium Front End Research and Development (MFERD)
- CANMET-MTL
- Premier's Research Excellence Award (PREA)
- Canada Foundation for Innovation (CFI)
- Ryerson Research Chair (RRC)
Magnesium alloys are increasingly used in automotive and aerospace industries for weight reduction and fuel economy improvement. Low cycle fatigue (LCF) behavior of these alloys is an important consideration for the structural applications. The objective of the present investigation was to identify influences of strain ratio and strain rate on cyclic deformation characteristics and fatigue life of an AZ31 extruded alloy. As the strain ratio decreased, stronger cyclic hardening rate, more asymmetric hysteresis loop, smaller stress amplitude, lower mean stress, and higher initial plastic strain amplitude were observed due to increasing compressive stresses. This was considered to be associated with the twinning during cyclic deformation in the compressive phase, and detwinning in the tensile phase. The residual twins acting as barriers to dislocation slip and pile-up were considered to be the main cause for the occurrence of cyclic hardening. Fatigue life increased with decreasing strain ratio and increasing strain rate. Fatigue crack initiation occurred at the specimen surface due to the presence of larger grains near the surface, and fatigue crack propagation was characterized by a mixture of striations and dimple-like ductile fracture features. (C) 2009 Elsevier B.V. All rights reserved.
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