Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy

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	Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy
	A. H. Feng; D. L. Chen; Z. Y. Ma
	2010
发表期刊	Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science
ISSN	1073-5623
卷号	41A 期号:4 页码:957-971
摘要	Microstructural changes and cyclic deformation characteristics of friction-stir-welded 7075 Al alloy were evaluated. Friction stir welding (FSW) resulted in significant grain refinement and dissolution of eta' (Mg(Zn,Al,Cu)(2)) precipitates in the nugget zone (NZ), but Mg(3)Cr(2)Al(18) dispersoids remained nearly unchanged. In the thermomechanically affected zone (TMAZ), a high density of dislocations was observed and some dislocations were pinned, exhibiting a characteristic Orowan mechanism of dislocation bowing. Two low-hardness zones (LHZs) between the TMAZ and the heat-affected zone (HAZ) were observed, with the width decreasing with increasing welding speed. Cyclic hardening and fatigue life increased with increasing welding speed from 100 to 400 mm/min, but were only weakly dependent on the rotational rate between 800 and 1200 rpm. The cyclic hardening of the friction-stir-welded joints exhibiting a two-stage character was significantly stronger than that of the base metal (BM) and the energy dissipated per cycle decreased with decreasing strain amplitude and increasing number of cycles. Fatigue failure occurred in the LHZs at a lower welding speed and in the NZ at a higher welding speed. Fatigue cracks initiated from the specimen surface or near-surface defects in the friction-stir-welded joints, and the initiation site exhibited characteristic intergranular cracking. Crack propagation was characterized by typical fatigue striations along with secondary cracks.
部门归属	[chen, d. l.] ryerson univ, dept mech & ind engn, toronto, on m5b 2k3, canada. [ma, z. y.] chinese acad sci, shenyang natl lab mat sci, inst met res, shenyang 110016, peoples r china.;dchen@ryerson.ca
关键词	Strength Aluminum-alloys Fatigue-crack-growth Mg-cu Alloys Zn-mg Dynamic Recrystallization Mechanical-properties Welding Parameters Residual-stresses Grain-refinement Butt Joints
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WOS记录号	WOS:000275445100024
引用统计	被引频次：124[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/31095
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	A. H. Feng,D. L. Chen,Z. Y. Ma. Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy[J]. Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,2010,41A(4):957-971.
APA	A. H. Feng,D. L. Chen,&Z. Y. Ma.(2010).Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy.Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science,41A(4),957-971.
MLA	A. H. Feng,et al."Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy".Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science 41A.4(2010):957-971.