Metallurgical factors affection Vickers hardness of friction stir welded joint of 7075 aluminum alloy

The repair of high strength, high performance 7075 aluminum alloy is essential for a broad range of aerospace and defense applications. However, it is challenging to implement it using traditional fusion welding-based approaches, owing to hot cracking and void formation during solidification. Here, the use of an emerging solid-state additive manufacturing technology, additive friction stir deposition, is explored for the repair of volume damages such as through -holes and grooves in 7075 aluminum alloy. Three repair experiments have been conducted: double through-hole filling, single through-hole filling, and long, wide-groove filling. In all experiments, additive friction stir deposition proves to be effective at filling the entire volume. Additionally, sufficient mixing between the deposited material and the side wall of the feature is always observed in the upper portions of the repair. Poor mixing and inadequate repair quality have been observed in deeper portions of the filling in some scenarios. Based on these observations, the advantages and disadvantages of using additive friction stir deposition for repairing volume damages are discussed. High quality and highly flexible repairs are expected with systematic optimization work on process control and repair strategy development in the future.

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Exploring the effects of SiC reinforcement incorporation on mechanical properties of friction stir welded 7075 aluminum alloy: Fatigue life, impact energy, tensile strength

Materials Science and Engineering A ◽

10.1016/j.msea.2013.11.068 ◽

2014 ◽

Vol 595 ◽

pp. 173-178 ◽

Cited By ~ 47

Author(s):

Mohsen Bahrami ◽

Nader Helmi ◽

Kamran Dehghani ◽

Mohammad Kazem Besharati Givi

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Aluminum Alloy ◽

Fatigue Life ◽

Impact Energy ◽

7075 Aluminum Alloy ◽

Friction Stir ◽

Life Impact ◽

Sic Reinforcement

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Study on the Microstructure and Mechanical Properties of Welding Joints of 7A05 Aluminum Alloy by FSW

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.496-500.110 ◽

2014 ◽

Vol 496-500 ◽

pp. 110-113

Author(s):

Dong Gao Chen ◽

Jin He Liu ◽

Zhi Hua Ma ◽

Wu Lin Yang

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Friction Stir Welding ◽

Welding Speed ◽

Welded Joint ◽

Optical Microscope ◽

Nugget Zone ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Welding Joints

The7A05 aluminum alloy of the 10mm thickness was welded by the friction stir welding. The microstructure and mechanical Properties of the welded joint was researched by the optical microscope, etc. The results showed: the microstructure of the weld nugget zone and the thermal mechanically affected zone were refined as the welding speed increasing when the rotate speed is constant. As the welding speed increasing the strength of extension of the welded joint is increasing at first and then stable basically. but the yield strength had no obvious change.

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Microstructure and nanomechanical behavior of friction stir welded joint of 7055 aluminum alloy

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2020.11.016 ◽

2021 ◽

Vol 61 ◽

pp. 311-321

Author(s):

Wen Wang ◽

Shengnan Yuan ◽

Ke Qiao ◽

Kuaishe Wang ◽

Shengyi Zhang ◽

...

Keyword(s):

Aluminum Alloy ◽

Welded Joint ◽

Friction Stir ◽

7055 Aluminum Alloy

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Study on the Precipitation Behavior of Precipitates of 7075 Aluminum Alloy Friction Stir Welding Joint

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1003.37 ◽

2020 ◽

Vol 1003 ◽

pp. 37-46

Author(s):

Hao Zhu ◽

Shao Kang Dong ◽

Ze Ming Ma ◽

Jun Wang

Keyword(s):

Aluminum Alloy ◽

Friction Stir Welding ◽

Strain Hardening ◽

Strengthening Effect ◽

7075 Aluminum Alloy ◽

Friction Stir ◽

Microhardness Distribution ◽

Fine Grain ◽

Fine Grain Strengthening ◽

Precipitated Phases

In this work, the microhardness of 7075 aluminum alloy friction stir welding (FSW) joint was measured by a micro vickers hardness tester, the microstructure of the joints was characterised by microscope, the precipitated phases among the welding nugget zone (WNZ), thermal mechanical affected zone (TMAZ), heat affected zone (HAZ) were affirmed by X-ray diffractometer (XRD) and the lattice fringe of transmission electron microscopy (TEM) high resolution image. Based on this, the precipition behavior of precipitated phases was studied. The results show that the microhardness distribution of the 7075 aluminium alloy FSW joints is heterogeneous in comparison with the base metal (BM). The precipitates in the joint mainly include MgZn rod shape and AlCuMg in elliptical shape. In the WNZ, the main precipitate is AlCuMg, and the fine grain strengthening effect is better, so the microhardness in this zone is relatively high. In the TMAZ, the quantity of AlCuMg decreased while the MgZn2 increased relatively in comparison with the WNZ. At the same time, the effect of the fine grain strengthening was weakened, though the strain hardening increased. Therefore, the microhardness in the TMAZ still decreased. In the HAZ, the quantity of MgZn2 increased furtherly, and there is no strain hardening and fine grain strengthening, so the microhardness of the HAZ was the lowest among the FSW joints. Besides, through comparative tests, the optimal process parameters of friction stir welding of 7075 aluminum alloy were obtained.

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Evolution of Microstructure and Mechanical Properties in a Single-Stage Aged 7075 Aluminum Alloy Pulse Variable Polarity Plasma Arc Welded Joint

Metals ◽

10.3390/met9040428 ◽

2019 ◽

Vol 9 (4) ◽

pp. 428

Author(s):

Guowei Li ◽

Yahong Liang ◽

Furong Chen ◽

Yongquan Han ◽

Li Sun

Keyword(s):

Tensile Strength ◽

Aluminum Alloy ◽

Aging Temperature ◽

Welded Joint ◽

Single Stage ◽

Precipitate Size ◽

7075 Aluminum Alloy ◽

Plasma Arc ◽

Variable Polarity ◽

Variable Polarity Plasma Arc

A 7075 aluminum alloy was successfully welded by pulsed variable polarity plasma arc welding (PVPPAW) and the single-stage aging behavior of the 7075 aluminum alloy PVPPAW joint was systematically investigated. The results demonstrated that the tensile strength of the welded joints initially increased and then decreased with the increase of the single-stage aging temperature and time. After single-stage aging at 490 °C for 80 min and at 130 °C for 24 h, the tensile strength of the welded joint was 551 MPa, which was increased by 38.5% compared to the as-welded joint. Moreover, the conductivity was 25% international annealed copper standard (IACS) at room temperature, and the resistance to stress corrosion was improved. The main strengthening phases of the weld center were η′ and η phase. The average precipitate size slightly increased with the increase of the single-stage aging temperature, but no obvious change was observed with the increase of the single-stage aging time. The area fraction was initially increased and then decreased with the increase of the single-stage aging temperature and time.

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