A Study on Microstructure and Mechanical Properties of Micro Friction Stir Welded Ultra-Thin Al-1060 Sheets by the Shoulderless Tool

Abstract

The welding tool is the key of micro friction stir welding (μFSW), which affects the heat input and the plastic forming of weld metal. In this paper, 0.8-mm-thick ultra-thin 1060-H24 aluminum sheets μFSW butt joints were used to compare and analyze the influence of the conventional tool and shoulderless tool on weld shaping, microstructure and mechanical properties. Besides, by measuring the axial force, transverse force and weld temperature in μFSW process, the influence of these two different tools on the heat input and metal flow mechanism of the weld were analyzed. The results show that the weld generated by the shoulderless tool has narrower width, less heat input and metal involved in plastic forming resulting in smaller HAZ (heat affected zone). The hardness of NZ (nugget zone) is obviously increased compared with that of the base metal. The highest tensile strength can reach 108.6 MPa, accounting for 78.6% of the base metal and 117.3% of the joint by the conventional tool. But the welding defects have to be overcome for industrial application of the shoulderless tool.

Research on the Friction Stir Welding of Sc-Modified AA2519 Extrusion

“…Friction stir welding (FSW) is a solid-state welding process invented by The Welding Institute (TWI), which provides many advantages compared to conventional welding processes [1][2][3]. Using FSW it is possible to obtain high-quality joints of aluminum alloys, what makes this technology very attractive for the automotive, aerospace, and shipbuilding industry [2,4,5]. Recent research indicates that this technology also provides wide possibilities in the manufacturing of light-alloy based metal-ceramic composites, welding of dissimilar alloys, and modification of surface [6][7][8][9][10].…”

“…tool rotation speed and tool traverse speed [38,42]. Although the most commonly aluminum alloys used in industry were widely examined in terms of the parameters-properties relationship, publications on the Sc-containing aluminum alloys are still a significant research gap [1,2,5,10,33,38,40]. In the case of AA2519 alloy, only a few investigations are concerned with the influence of friction stir welding on the properties of the joint [10,20,43].…”

Weldability Investigation and Optimization of Process Variables for TIG‐Welded Aluminium Alloy (AA 8006)

“…e AA2024 was successfully applied with a new welding approach by TIG β FSP to improve the mechanical properties of the TIG-welded joints. ey find that TIG welding joint defects and porosities are fully reduced by the FSP method and the microstructure and mechanical properties of the welded joint were increased by using of FSP; it has been altered [19] effectively. Using the FSP on the TIG-welded joint, the ductility and the tensile strength of the welding joint AA5083-H112 FSP and TIG were improved [20].…”

Shoulderless Friction Stir Welding: a low-force solid state keyhole joining technique for deep welding of labile structures

“…However, with a typical opening angle between 70 and 160 • [19] contact area and so normal forces increase fast with increasing welding depth analogous to the standard FSW process, e. g. exactly quadratic for a 90 • opening angle as used by Lammlein et al [10]. Accordingly, Zhang et al report very similar normal force values compared to their standard FSW reference process when applying EWI's concept to FSW [22].…”