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

Feng, A.H.; Chen, D.L.; Ma, Zheng

doi:10.1007/s11661-009-0152-3

Cited by 116 publications

(64 citation statements)

References 59 publications

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“…1-Schematic illustration of friction-stir-welded 6061Al-T651 joints showing fatigue specimen machining, microindentation hardness test path, and various zones (BM, HAZ, TMAZ, and NZ) across the weld. [32] *JEOL is a trademark of Japan Electron Optics Ltd., Tokyo, Japan. section of 32 9 6 9 5.6 mm in size, were machined perpendicular to the FSW direction, as indicated in Figure 1.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

“…Our previous work on frictionstir-welded 7075Al-T651 alloy has indicated that cyclic hardening and fatigue life increased with increasing welding speed, but were only weakly dependent on the pin tool rotational rate; the cyclic hardening of the friction-stir-welded joints exhibited a two-stage character. [32] To date, no LCF information of the friction-stirwelded 6xxx-series aluminum alloy is available in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Low-Cycle Fatigue of a Friction-Stir-Welded 6061 Aluminum Alloy

Feng

Chen

2010

Metall Mater Trans A

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Strain-controlled low-cycle fatigue (LCF) tests and microstructural evaluation were performed on a friction-stir-welded 6061Al-T651 alloy with varying welding parameters. Friction stir welding (FSW) resulted in fine recrystallized grains with uniformly distributed dispersoids and dissolution of primary strengthening precipitates b¢¢ in the nugget zone (NZ). Two low-hardness zones (LHZs) appeared in the heat-affected zone (HAZ) adjacent to the border between the thermomechanically-affected zone (TMAZ) and HAZ, with the width decreasing with increasing welding speed. No obvious effect of the rotational rate on the LHZs was observed. Cyclic hardening of the friction-stir-welded joints was appreciably stronger than that of base metal (BM), and it also exhibited a two-stage character where cyclic hardening of the frictionstir-welded 6061Al-T651 alloy at higher strain amplitudes was initially stronger followed by an almost linear increase of cyclic stress amplitudes on the semilog scale. Fatigue life, cyclic yield strength, cyclic strain hardening exponent, and cyclic strength coefficient all increased with increasing welding speed, but were nearly independent of the rotational rate. Most friction-stirwelded joints failed along the LHZs and exhibited a shear fracture mode. Fatigue crack initiation was observed to occur from the specimen surface, and crack propagation was mainly characterized by the characteristic fatigue striations. Some distinctive tiremark patterns arising from the interaction between the hard dispersoids/inclusions and the relatively soft matrix in the LHZ under cyclic loading were observed to be present in-between the fatigue striations.

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Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microstructure and Low-Cycle Fatigue of a Friction-Stir-Welded 6061 Aluminum Alloy

Feng

Chen

2010

Metall Mater Trans A

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“…He carried out the hardness testing to determine the response of the FSWed specimens to different aging times. Feng et al [5] studied the microstructural changes and cyclic deformation of FSWed AA7075-T651. Su et al [6] investigated the microstructural evolutions of friction stir-processed AA7075-T6 in different regions behind the pin tool.…”

Section: Introductionmentioning

confidence: 99%

“…Despite a large number of investigations conducted on the properties of Al7075 joined by FSW [3][4][5][6][7][8], there is almost no work on the FSW of AA7075 with O temper. Almost all the past works on the FSW of AA7075 are pertaining to T6 or T651 condition which exhibits the highest strength before welding.…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution and mechanical properties during the friction stir welding of 7075-O aluminum alloy

Dehghani

Ghorbani

Soltanipoor³

2014

Int J Adv Manuf Technol

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In the present work, the AA7075-O was subjected to friction stir welding. The rotating and welding speeds were 630 rpm and 32 mm/min, respectively. The diameters of shoulder and pin were 30 and 5.7 mm, respectively. The length of threaded pin was 4.8 mm. The tensile, bending, and hardness tests were carried out on the friction stirwelded specimens. The results show that the strength of friction stir-welded sample was about 15 % (i.e., 25 MPa) higher than that of base metal. By contrast, the ductility of base metal was as much as twice that of friction stirwelded one. According to the obtained hardness profile, the maximum hardness was obtained for the stirred zone with a continuous decrease toward the base metal. This resulted in the formation of cracks after bending specimens prepared from weldment, while there was no sign of crack in the bent specimens taken from base metal. Besides, there are microstructural evolutions from the weldment toward the base metal. These include the variations in the size and distribution of precipitates. The precipitates were coarser in the heat-affected zone, while they were finer in the stirred zone.

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“…The 7075 aluminium alloy, in which zinc is the main alloying element, is a precipitation hardened alloy. It is one of the strongest aluminium alloys which is used in many spatial structures and places that require high strength-to-weight ratio [5][6]. Titanium and its alloys have high specific strength and good corrosion resistance and because of these two desirable properties, they have been widely used in the aerospace industry.…”

Section: Introductionmentioning

confidence: 99%

Friction Stir Welding of Dissimilar Joints Between Commercially Pure Titanium Alloy and 7075 Aluminium Alloy

2017

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SummaryIn this study, a joint between commercially pure titanium alloy and 7075 aluminium alloy was butt welded by using friction stir welding at a rotational speed of 1120 rpm and a traverse speed of 50 mmmin -1 . The evaluation of hardness and microstructure was performed by using scanning electron microscopy. The phases in the weld area were identified by applying the X-ray diffraction technique and the Energy Dispersive X-ray Spectroscopy (EDS) analysis was used for the evaluation of intermetallic compounds of the weld area. The weld zone is cone-shaped and consists of aluminium and titanium particles that play an important role in increasing hardness and tensile strength. The weld area has three zones, namely the titanium base metal zone, the aluminium base metal zone, and the titanium-aluminium intermetallic compound mixed zone. It was also observed that the joint area on the aluminium side includes the stirred area, the thermo-mechanically affected zone, and the heat-affected zone, while the titanium joint area contains the stirred zone and the heat-affected zone. The hardness value of the weld area was around 360 HV, which means that in this area, compared to the base metal of titanium and aluminium, hardness has increased by 6% and 20%, respectively. This can be attributed to severe plastic deformation and formation of intermetallic compounds of titanium and aluminium in this area.

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

Cited by 116 publications

References 59 publications

Microstructure and Low-Cycle Fatigue of a Friction-Stir-Welded 6061 Aluminum Alloy

Microstructure and Low-Cycle Fatigue of a Friction-Stir-Welded 6061 Aluminum Alloy

Microstructural evolution and mechanical properties during the friction stir welding of 7075-O aluminum alloy

Friction Stir Welding of Dissimilar Joints Between Commercially Pure Titanium Alloy and 7075 Aluminium Alloy

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