Fatigue properties of 6061-T6 aluminum alloy butt joints processed by vacuum brazing and tungsten inert gas welding

Lin, Hsin-Yi; Hwang, Jiun Ren; Fung, Chin Ping

doi:10.1177/1687814016643454

Cited by 8 publications

(3 citation statements)

References 19 publications

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“…AWS D1.2 specifies a strength reduction of 40% associated with the HAZ formed during metal inert gas (MIG) welding of 6061, or a minimum retained strength of 165 MPa [41]. In addition, published data indicate comparable strength levels in tungsten inert gas (TIG) welded 6061, 169 -174 MPa [42].Thus, the results indicate AFSD provides some improvement in strength relative to 'acceptable' strength levels associated with relevant fusion processes, such as MIG and TIG welding.…”

Section: Discussionmentioning

confidence: 99%

Repair of Aluminum 6061 Plate by Additive Friction Stir Deposition

Martin

Luccitti

Walluk

2021

Preprint

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The deposition of new alloy to replace a worn or damaged surface layer is a common strategy for repairing or remanufacturing structural components. For high-performance aluminum alloys common in the automotive, aerospace, and defense industries, however, traditional fusion-based deposition methods can lead to solidification cracking, void formation, and loss of strength in the heat affected zone. Solid state methods, such as additive friction stir deposition (AFSD), mitigate these challenges by depositing material at temperatures below the melting point. In this work, a solid state volumetric repair was performed using AFSD of aluminum alloy 6061-T6 to fill grooves machined into the surface of a plate of 6061-T651. The groove-filling process is relevant to replacement of cracked or corroded material after removal by localized grinding. Three groove geometries were evaluated by means of metallographic inspection, tensile testing, and fatigue testing. For the process conditions and groove geometries used in this study, effective repairs were achieved to a depth of 3.1 – 3.5 mm. Below that depth, the interface between the substrate and AFSD filler exhibited poor bonding associated with insufficient shear deformation. The mechanical properties of the filler alloy, the depth of the heat affected zone, and areas for further optimization are discussed within the context of precipitation hardened aluminum alloys.

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Section: Discussionmentioning

confidence: 99%

Repair of Aluminum 6061 Plate by Additive Friction Stir Deposition

Martin

Luccitti

Walluk

2021

Preprint

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“…During microstructural analysis, it was observed that the grain re nement has taken place in the order of SZ < TMAZ < HAZ < BM, with average grain size of 4.77 µm in the SZ, 9.6 µm in the TMAZ, 56.73 µm in the HAZ, and 83 µm in the BM. Since the AA6061 is a heat treatable alloy, the precipitations of Mg 2 Si in Al 6061 are responsible to enhance the strength of the alloy [40]. Several investigations have demonstrated that the hardness of the aluminum alloys was mostly affected by precipitate distribution rather than grain size [41].…”

Section: Micro-hardnessmentioning

confidence: 99%

Effect of copper donor material-assisted friction stir welding of AA6061-T6 alloy on downward force, microstructure, and mechanical properties

Bhukya

Maniscalco

et al. 2022

Int J Adv Manuf Technol

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In this research, Copper (Cu) donor material assisted friction stir welding (FSW) of AA6061-T6 alloy was studied. Cu assisted FSW joints of AA6061-T6 alloy were prepared at a constant tool rotational rate of 1400 rpm and various welding speeds at 1 mm/s and 3 mm/s. The Cu donor material of different thickness (i.e., 20%, 40%, and 60%) with respect to the workpiece thickness was selected to assist the FSW joining at the plunge stage. It is observed that the downward force generated in the FSW process was gradually decreased after introducing Cu donor material with incremental thicknesses with respect to workpiece at the plunge stage. Post-weld analysis was characterized in terms of microstructure, and mechanical properties. The results of microstructure analysis at the stir zone (SZ) show the formation of ner grains due to dynamic recrystallization and plastic deformation. Microhardness tests reveal that the hardness decreased from the base metal (BM) to the SZ across the heat affected zone (HAZ) and thermo-mechanically affected zone (TMAZ). The lowest value of hardness appeared in the TMAZ and HAZ where tensile failure occurs. With increasing welding speed, the average hardness in the SZ decreased due to lower heat input and faster cooling rate. Tensile test plots show no signi cant change in ultimate tensile strength with or without Cu donor material. Fractography of tensile tested samples shows both ductile and brittle like structure for given welding parameters. This proposed work of FSW with Cu donor material is promising to increase tool life due to the decrement of the downforce during plunge and throughout the welding stage. Meanwhile, the inclusion of donor material did not compromise the weld quality in terms of the mechanical properties and micro-hardness. What Is Your Main Contribution To The Field?The main contribution in this research is on the novel and solid experimental approaches to examine whether donor material can assist friction stir welding (FSW) processes. To investigate this research question, Copper (Cu) was adopted as the donor material to assist the FSW of Al 6061. Through comparing experiments with and without donor material inclusion in FSW, it was found that the donor material induces drastic decreasing in downward force during FSW processes, which will increases the lifetime of the FSW tools. Meanwhile, the post-weld analysis identi ed no signi cant change occurred in the mechanical properties and microstructure of the welded joints, which is desired for industrial applications. The implementation of the donor material is promising to increase the lifetime of the FSW tools without compromising the mechanical properties FSW joints. The proposed approach is also economical for industrial application due to its effective potential to enhance the life of friction stir tools. What is novel? In theory, in experimental techniques, or a combination of both?This paper presents the novel experimental approach of introducing a Copper (Cu) donor material during the initial stage of friction sti...

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“…Although it has a perfect melting temperature, its wettability is much worse than that of Al-Si alloy, and more importantly, the corrosion resistance of Al-Zn alloy is much lower than that of Al-Si alloy, which makes it difficult to be used in heat exchangers [ 17 , 18 ]. Mg can break oxide film on the surface of aluminum alloys in vacuum conditions since Mg has stronger atomic activity and higher vapor pressure than Al, making Al-Mg alloy often used as a vacuum brazing filler metal [ 19 , 20 , 21 ]. However, due to the low production efficiency of vacuum brazing technology and the pollution of Mg steam to equipment, its application is not as wide as that of NOCOLOK flux brazing technology.…”

Section: Introductionmentioning

confidence: 99%

Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

Gao

Qin

2022

Materials

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3003 aluminum alloy was widely used for the manufacturing of heat exchangers in the automotive industry by employing controlled atmosphere brazing (CAB) with NOCOLOK flux brazing technology. However, commercially available filler metals for NOCOLOK flux brazing technology are usually required to be carried out at a relatively high temperature, causing the assembled heat exchanger to be partially molten or easily deformed. A new low-melting-point brazing filler metal Al-5.0Si-20.5Cu-2.0Ni was prepared by using melt-spinning technology and then applied to CAB of 3003 aluminum alloy in this research. The solidus and liquidus of brazing filler metal was 513.21 °C and 532.48 °C. All elements were evenly distributed and free from elemental segregation. The microstructure of brazing filler metal was uniform, and the grain size was less than 500 nm. As the brazing temperature reached 575 °C, the void in the joint disappeared completely. The morphology of CuAl2 was sensitive to the brazing temperature and dwell time. The appearance of net-like CuAl2 brazed at 575 °C for 20 min was more beneficial to improve joint mechanical properties. The leakage rate of the joint was qualified to be 10−10 Pa·m3/s when the brazing temperature was 570 °C or higher. The maximum shear strength of 76.1 MPa can be obtained when the joint was brazed at 575 °C for 20 min. More dwell time induced growth of the interfacial layer and reduced joint shear strength. The open circuit potential and corrosion current density test indicated that the brazing filler metal Al-5.0Si-20.5Cu-2.0Ni had better corrosion resistance than that of 3003 aluminum alloy.

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Fatigue properties of 6061-T6 aluminum alloy butt joints processed by vacuum brazing and tungsten inert gas welding

Cited by 8 publications

References 19 publications

Repair of Aluminum 6061 Plate by Additive Friction Stir Deposition

Repair of Aluminum 6061 Plate by Additive Friction Stir Deposition

Effect of copper donor material-assisted friction stir welding of AA6061-T6 alloy on downward force, microstructure, and mechanical properties

Controlled Atmosphere Brazing of 3003 Aluminum Alloy Using Low-Melting-Point Filler Metal Fabricated by Melt-Spinning Technology

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