New technique of filling friction stir welding

Abstract

A new technique of filling friction stir welding (FFSW) relying on a semiconsumable joining tool has been developed to repair the keyhole left at the end of friction stir welding (FSW) seam. The conventional nonconsumable tool of FSW was transformed, and a semiconsumable joining tool consisting of alloy steel shoulder and aluminium alloy joining bit was designed to create a solid state joint. Using the combined plastic deformation and flow of the consumable joining bit and the wall of the keyhole, the FFSW process is able to repair the keyhole with both metallurgical and mechanical bonding characteristics, and the FSW seam can be achieved without keyhole or other defects. The relative tensile strength and elongation of the FFSW joint are 84?3 and 98?9% of the base weld without defects respectively.

Investigation of vertical compensation friction stir-welded 7N01-T4 aluminum alloy

“…Therein, microhardness distribution in the top and bottom is 1 and 3 mm to the top surface, respectively. As commonly seen in the traditional FSW, the softening phenomenon is occurred in the VCFSW joint of 7N01 alloy, which is attributed to dissolution, reprecipitation, and coarsening of strengthening precipitates [31,32]. The average value of NZ is lower than BM but higher than that of HAZ and TMAZ, which is due to the fine and equaixed microstructures resulted from dynamic recrystallization of NZ.…”

Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

“…To avoid it, several methods have been developed. These include the refilling friction stir welding (RFSW) that adopts a telescopic stir-pin for welding [4][5][6], which is invented by GKSS (a national research centre in Germany ) at firstly, pinless or probeless friction stir spot welding [7][8][9], friction plug welding (FPW) [10][11][12][13], filling friction stir welding that adopts a retention pin [14], and fusion welding filling [15]. Although these techniques could effectively eliminate the keyhole in some cases, each appears to have some restrictions in practice.…”

Interface behavior and mechanical properties of 316L stainless steel filling friction stir welded joints

“…Recently, a new technique called filling friction stir welding (FFSW) has been proposed by Huang et al, where a semi-consumable tool consisting of a non-consumable shoulder and consumable joining bit is used to repair the keyholes in aluminum alloy FSW [15,16]. However, very little attention has been given to keyhole repair in austenitic stainless steel despite their potential industrial importance [17,18].…”