Sustainability of friction stir welded AA6082 plates through post-weld solution heat treatment

In this study, 6 mm thick AA6061-T6 plates were friction stir welded (FSWed) at different traveling speeds while Al2O3 nano-particles were incorporated between adjoining plates. The solution heat treatment was applied on samples for one hour at 540 ℃ and subsequently aged for 18 h at 180 ℃ to investigate the effect of post-weld heat treatment on mechanical properties of specimens. All joints were investigated macro- and micro-structurally. The microstructural characterization of the FSWed samples was carried out using scanning electron microscopy (SEM) and light microscopy techniques. Distribution of Al2O3 nano-particles in the stir zone was studied by SEM. The specimen FSWed at 40 mm/min exhibited the most homogeneous particles distribution. Tensile properties including ultimate tensile strength, elongation, and fracture surfaces were studied. Microhardness of specimens was also investigated. Surprisingly, all specimens exhibited inferior hardness compared to the as-received AA6061-T6 alloy. This phenomenon was attributed to the dissolution of precipitates during FSW process.

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Pengaruh Solution Heat Treatment terhadap Sifat Fisis dan Mekanik Proses Pengelasan Fssw AA6063-T5

Mekanika: Majalah Ilmiah Mekanika ◽

10.20961/mekanika.v17i1.35044 ◽

2018 ◽

Vol 17 (1) ◽

Author(s):

Ciptadi Natawiguna ◽

Nurul Muhayat ◽

Teguh Triyono

Keyword(s):

Heat Treatment ◽

Aluminum Alloy ◽

Temperature Variation ◽

Solution Heat Treatment ◽

Aluminum Matrix ◽

Physical And Mechanical Properties ◽

Hardness Test ◽

Holding Time ◽

Tensile Shear ◽

Friction Stir

Friction stir spot welding (FSSW) of aluminum alloy AA6063-T5 will decrease the strength and hardness. Physical and mechanical properties of aluminum alloy can be improved by heat treatment. Heat treatment is affected by temperature and holding time. The heat treatment process used for this research was solution heat treatment with temperature variation 470, 500, 530 oC and holding time 1 and 2 hours. The tests included microstructure test, tensile shear test and vickers hardness test. Result of the research, it was found that Mg2Si particles were precipitated from the grain boundaries part into the aluminum matrix with the coarser size and the distance was increasing as the temperature and the holding time increases. The highest shear tensile strength of 3735,2 N was obtained from the temperature variation of 470 oC and the holding time of 1 hour. The lowest tensile shear strength of 3172,6 N was obtained from temperature variation of 530 oC and 2 hours of holding time. The highest hardness value was obtained of 470 oC variation and 1 hour was 43,7 HVN and the lowest hardness value at 530 oC variation and 2 hours of holding time was 30,1 HVN.

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Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.3.2020.08.0612 ◽

2020 ◽

Vol 17 (3) ◽

pp. 8150-8159

Author(s):

Kulwant Singh ◽

Gurbhinder Singh ◽

Harmeet Singh

Keyword(s):

Heat Treatment ◽

Friction Stir Welding ◽

Magnesium Alloys ◽

Mechanical Performance ◽

Fuel Efficiency ◽

Research Work ◽

Grain Structure ◽

Tensile Fracture ◽

Friction Stir ◽

The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

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