High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

Abstract

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailorwelded blank technology for aluminum alloys at high volumes. While frictionstir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of highvolume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy

“…One of the factors hindering the widespread application of FSW is its relatively slow welding speed, which is usually hundreds of millimeters per minute. Recent developments in tool and equipment for the FSW process have enabled an implementation of the higher welding speeds up to 3 m/min [18]. Previous research findings of the high-speed friction stir welding (HSFSW) [19][20][21][22][23][24][25][26] have demonstrated that the defect-free joints of various aluminum alloys (even by welding of ultra-thin sheets) can be observed after HSFSW through an adjustment of the welding parameters and tool geometry.…”

Friction Stir Weldability at High Welding Speed of Two Structural High Pressure Die Casting Aluminum Alloys

“…However, a lower hardness is expected for the coarser Si structure observed in the WN zone in comparison to base material in the present work. Concerning the hardness profile of the AlMg4Fe2 weld, the typical shape of friction stir weld in non-hardenable aluminum alloys [57] and in Al-Mg2Si composites [21] is observed. This shape consists of a zone of higher hardness in the center (nugget) surrounded by zones of lower hardness (TMAZ and HAZ).…”

Digital Image Correlation Characterization and Formability Analysis of Aluminum Alloy TWB during Forming

“…As TWBs can be produced of dissimilar alloys and dissimilar thicknesses, further weight reduction can be achieved for automotive applications based on structural design, which enables local design requirements to be matched with alloy and/or thickness. An example of such mass optimization was documented for a front-door inner panel, where 5 kg was reduced by using aluminum alloy tailor-welded blanks compared to steel tailor-welded blanks [ 5 ], and dissimilar thicknesses were used to enable local structural requirements at the door hinge without adding weight to the entire panel.…”

“…Several studies specifically evaluated the influence that strength or thickness ratios have on the overall formability of the TWB [ 7 , 10 ]. Other studies focus on the influence of welding methods and parameters on the formability of TWBs [ 5 , 11 , 12 , 13 ], with recent studies working to improve friction stir welding (FSW) with ultra-sonic vibration [ 14 ]. Numerous studies focus on the optimization of FSW specifically for the formability of TWBs.…”

“…Numerous studies focus on the optimization of FSW specifically for the formability of TWBs. These studies focus on tooling and weld parameters, with a consensus that increasing welding speed leads to improved formability [ 5 , 14 , 15 ]. Further evaluation of the influence of welding on the formability was reported by Parente et al [ 11 ], showing the influence of weld direction on the overall formability of TWBs.…”