Texture Development in a Friction Stir Lap-Welded AZ31B Magnesium Alloy

Naik, B. S.; Chen, D.L.; Cao, X.; Wanjara, P.

doi:10.1007/s11661-014-2372-4

Cited by 20 publications

(8 citation statements)

References 59 publications

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“…With increasing welding energy, the hardness in the NZ linearly decreased due to increase in the grain size. Similar results were obtained during USW and FSSW of AZ31 Mg alloy[42,80,140].Grain boundaries are major barriers to the slip of dislocations. This means that finer grains at a lower welding energy would have a greater resistance to localized plastic deformation, i.e., a higher hardness or strength, due to more grain boundaries compared with larger grains at a higher welding energy.…”

supporting

confidence: 82%

Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

Macwan¹

2021

Preprint

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Lightweighting has been regarded as a key strategy in the automotive industry to improve fuel efficiency and reduce anthropogenic environment-damaging, climate-changing, and costly emissions. Magnesium (Mg) alloys and Aluminum (Al) alloys are progressively more used in the transportation industries to reduce the weight of vehicles due to their high strength-to-weight ratio. Similarly, high strength low alloy (HSLA) steel is widely used to reduce gauge thickness and still maintain the same strength, and thereby reduce vehicle weight as well. A multi-material design of automotive structures and parts inevitably involve similar Mg-to-Mg and dissimilar Mg-to-Al, Al-to-steel, and Mg-to-Cu joints. Ultrasonic spot welding (USW) – a solid-state joining technique has recently received significant attention due to its higher efficiency in comparison with conventional fusion welding techniques. In this study, USW was used to generate similar joints of low rare-earth containing ZEK100 Mg alloy sheets and dissimilar ZEK100-to-Al5754, Al6111-to-HSLA steel, and Mg-to-Cu joints at different levels of welding energy or welding time. To optimize welding process and identify key factors affecting the weld strength, microstructural evolution, microhardness test, tensile lap shear test, fatigue test, and fracture analysis were performed on similar and dissimilar ultrasonic spot welded (USWed) joints. Dynamic recrystallization and grain coarsening were observed during Mg-to-Mg similar welding while rapid formation and growth of interface diffusion layer were observed in all dissimilar joints in the present study. It was due to significantly high strain rate (~103 s-1) and high temperature generated via frictional heating during USW. The interface diffusion layer was analyzed by SEM, EDS and XRD phase identification techniques which showed the presence of eutectic structure containing intermetallic compounds (IMCs). As a result, brittleness at the interface increased. The Zn coating in dissimilar USWed Al-to-steel joints eliminated the formation of brittle IMCs of Al-F, which were replaced by relatively ductile AlZn eutectic. The optimum welding energy or welding time during similar and dissimilar USW of lightweight alloys with a sheet thickness of 1-2 mm was in the range of ~500 J to 2000 J (~0.25 s to 1 s).

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confidence: 82%

Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

Macwan¹

2021

Preprint

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“…Typical coarse grains are expected in this zone compared to the SZ and TMAZ, which then decreases steadily across TMAZ and SZ [42,161]. However, there are results that suggest small grain sizes at BM with coarse grain observed for TMAZ and SZ [157]. This is generally affected by tool rotational and welding speeds.…”

Section: Base Metal (Bm)mentioning

confidence: 90%

“…The process does not have welding defects such as shrinkage, hot fracturing and porosity, significantly reduces the thermal stresses induced in the metals [49,156]. A typical friction stir welding process is shown in Figure 6 [157].…”

Section: Friction Stir Welding (Fsw)mentioning

confidence: 99%

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Welding of magnesium and its alloys: an overview of methods and process parameters and their effects on mechanical behaviour and structural integrity of the welds

et al. 2021

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An overview of welding methods and process parameters and its effects on mechanical behaviour and structural integrity of magnesium and its alloys are discussed. These alloys are less dense and beneficial structural alloys for improved energy efficiency, eco-friendliness and driver of circular economic model for sustainable design and innovative ecosystem. While the application of Mg-alloys is projected to increase, understanding the mechanical behaviour and structural integrity of welded joints are critical. Thus, fusion and solid-state welding processes of these alloys are discussed with emphasis on mechanical characterization. Laser welding is the most effective fusion welding technique for most Mg alloys whereas, the predominant solid-state method is friction stir welding. The importance of process variables such as heat inputs, welding velocity (speed) and post weld treatments on the microstructural evolution, on mechanical and physical properties of the distinct zones of the weld joints are described. The weldment is the most susceptible to failure due to phase transformation, defects such as microporosity and relatively coarse grain sizes after solidification. The implication of the design of quality weld joints of Mg alloys are explored with areas for future research directions briefly discussed.

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“…The texture distributions in SZ of Mg alloys can be optimized by adjusting FSW parameters673031323334. However, the extent of texture redistribution was usually limited by this method.…”

mentioning

confidence: 99%

Comparative study on twinning characteristics during two post-weld compression paths and their effects on joint enhancement

Liu

Xin

et al. 2016

Sci Rep

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Friction stir welding (FSW) has promising application potential in Mg alloys. However, the texture distribution in stir zone (SZ) is usually complicated for Mg alloys, which deterioriates the joint performance. In this study, the texture distribution in SZ was tailored by applying two kinds of post-weld compression deformation along normal direction (ND) or welding direction (WD) of the FSWed AZ31 Mg alloy plates. The twinning behavior and texture change in the various regions of SZ were then evaluated by electron back scatter diffraction (EBSD) characterization. The effect of texture change on the joint performance was discussed in terms of Schmid factors (SFs) for basal slip and extension twinning. The results showed that profuse extension twins were formed through the whole SZ for the sample subjected to compression along ND, whereas they were observed mainly in SZ-side for the sample compressed along WD. Most of the twins were present in the forms of twin bands or chains. The directions of the twin bands or chains were related to the habit plane traces of selected twin variants. The ND post-weld compression had better strengthening effects on the joints compared to the WD compression, and the underline mechanism was discussed.

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Texture Development in a Friction Stir Lap-Welded AZ31B Magnesium Alloy

Cited by 20 publications

References 59 publications

Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

Ultrasonic Spot Welding of Similar and Dissimilar Alloys for Automotive Applications

Welding of magnesium and its alloys: an overview of methods and process parameters and their effects on mechanical behaviour and structural integrity of the welds

Comparative study on twinning characteristics during two post-weld compression paths and their effects on joint enhancement

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