Enhancing mechanical properties of friction stir welded joints of Al-Si-Mg alloy through post weld heat treatments

This work developed dissimilar friction stir welded joints of AA6082-T6 and AA7050-T7 under different cooling environments namely conventional air, forced air, and water-cooling. Characteristics of developed weld joints were studied for macrostructure, microstructure, microhardness, tensile properties, and fractography. AA6082-T6 dominated in weld nugget macrostructure and proportion of same increased with increasing cooling rate, while weld width reduced remarkably with an increase in heat extraction rate. Welds had interlocking lobes-based flow structures superimposed over an intercalated lamellar layer of both metals. The cooling environment significantly affected the proportion of low/high angle grain boundaries, tensile properties, and hardness of weld nugget zones. The tensile specimens of all-welded joints were fractured from minimum hardness location in a ductile mode.

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“…Prolonged aging leads to the formation of few coarser precipitates and precipitate free zone resulting in reduced ductility. 34–36…”

Section: Resultsmentioning

confidence: 99%

Influence of cooling environment on microstructure and mechanical properties of AA6082-T6 and AA7050-T7 dissimilar friction stir welds

Singh

Upadhyay

Sharma³

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…9 During FSW of these precipitate hardening aluminum alloys, the thermal cycle prevailing in the welded joint causes coarsening and dissolution of precipitates in thermomechanically affected zone (TMAZ) and heat-affected (HAZ). [10][11] Further, softening due to the weld thermal cycle weakens the welded joints. 12 The extent of softening depends on the initial temper condition of base metal (BM) and weld thermal cycle.…”

Section: Introductionmentioning

confidence: 99%

“…9 During FSW of these precipitate hardening aluminum alloys, the thermal cycle prevailing in the welded joint causes coarsening and dissolution of precipitates in thermo-mechanically affected zone (TMAZ) and heat-affected (HAZ). 10–11…”

Section: Introductionmentioning

confidence: 99%

Effect of in-process cooling on microstructure and mechanical properties of dissimilar AA2014 and AA7075 friction stir welded joints

Kumar

Upadhyay

Misra

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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Heat-carrying capacity of a cooling medium is critical as it governs microstructure evolution and tensile properties during friction stir welding (FSW). In this research, three cooling techniques: conventional air-cooling (CAC), forced air-cooling (FAC), and water flow cooling (WFC), were employed to study the effect on microstructure and mechanical properties in dissimilar FSW of AA2014 and AA7075. In-process cooling significantly influenced weld microstructure, zone size, microhardness, and tensile properties, which varied with the cooling medium. Water flow cooling was the most effective cooling technique due to its higher heat carrying capacity than CAC and FAC. Water flow cooling resulted in a drastically refined grains structure of smaller size in all zones, had higher tensile strength, elongation, and heat-affected (HAZ) hardness than CAC and FAC. Greatly refined grain structure and less dissolution of precipitates in weld nugget zone (WNZ) along with smaller HAZ and thermo-mechanically affected zone (TMAZ) are responsible for improved weld properties of WFC than the FAC and CAC. Forced air-cooling resulted in a higher microhardness value at WNZ, followed by WFC and CAC. Fractured surfaces of the tensile specimen were scrutinized by scanning electron microscope. Cooling did not affect the fracture side and location; however, fracture mode changed with cooling medium viz. ductile for FAC and WFC and mixed-mode for CAC.

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“…The post-weld heat treatment (PWHT) has been targeted in the present research to improve the joint mechanical properties. PWHT can be a combination of solution heat treatment and aging treatment or merely an aging treatment after welding [17]. Applying bulk or local PWHT on AA2ÂÂÂ series leads to a fine and dense reprecipitation in the NZ [18], resulting in recovering the joint mechanical properties [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatments on microstructural and mechanical characteristics of dissimilar friction stir welded 2198/2024 aluminum alloys

Khalilabad

Zedan

Texier

et al. 2021

Journal of Adhesion Science and Technology

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Enhancing mechanical properties of friction stir welded joints of Al-Si-Mg alloy through post weld heat treatments

Cited by 10 publications

References 15 publications

Influence of cooling environment on microstructure and mechanical properties of AA6082-T6 and AA7050-T7 dissimilar friction stir welds

Influence of cooling environment on microstructure and mechanical properties of AA6082-T6 and AA7050-T7 dissimilar friction stir welds

Effect of in-process cooling on microstructure and mechanical properties of dissimilar AA2014 and AA7075 friction stir welded joints

Effect of heat treatments on microstructural and mechanical characteristics of dissimilar friction stir welded 2198/2024 aluminum alloys

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