Tensile Properties and Strain Hardening Behavior of a Friction Stir Welded AA2219 Al Alloy

Abstract

Microstructures, tensile properties and work hardening behavior of friction stir welded (FSWed) AA2219-T62 aluminum alloy (in its one-third bottom slice of a 20 mm thick plate) were evaluated at different strain rates. While the yield strength was lower in the FSWed joint than in the base metal, the ultimate tensile strength of the FSWed joint approached that of the base metal. In particular the FSW resulted in a significant improvement in the ductility of the alloy due to the prevention of premature failure caused by intergranular cracking along the second-phase boundary related to the presence of the network-like grain boundary phase in the base metal. While stage III and IV hardening occurred after yielding in both base metal and FSWed samples, the FSW led to stronger hardening capacity and higher strain hardening exponent and rate due to the enhanced dislocation storage capacity associated with the microstructural change after FSW. The fracture surface of the FSWed joint was mainly characterized by dimples and tearing ridges along with micropores.

Fiber Bragg Grating Sensors for the Detection of Metal Crack Initiation by Low Cycle Fatigue Test

“…Before FSW, the surface oxides were removed and then cleaned using ethanol. The FSW tool had a shoulder of 34 mm in diameter and a threaded (left-handed screw) cone-shaped pin of 13.5 mm in root diameter and 9.3 mm in tip diameter, and was rotated clockwise [26]. With a tool rotational rate at 300 rpm and traverse/welding speed of 80 mm/min the FSW was performed.…”

“…The cross section of the welded joint was ground with water abrasive papers, and then polished using diamond paste up to 1 μ m [26].It was then etched with Keller's reagent (1 ml hydrofluoric acid, 1.5 ml hydrochloric acid, 2.5 ml nitric acid and 95 ml distilled water), then the microstructure was examined using a light microscope in conjunction with an image analysis system [26]. Subsized tensile specimens with a gauge length of 35 mm (i.e., a parallel length of 32mm) and width of 6 mm in accordance with ASTM E8M standards, were cut perpendicularly to the welding directions (or the rolling direction for the base material) and sliced equally into three pieces (top, middle and bottom) in the thickness direction, and then machined to the required dimensions [26]. The gauge area of specimens was ground with SiC papers up to grit 600 along the loading axis to get rid of the cutting marks and to achieve a smooth surface [26] 3.3.4 Tensile properties and strain hardening behavior of FS W AA2219 Al Alloy:…”

“…Subsized tensile specimens with a gauge length of 35 mm (i.e., a parallel length of 32mm) and width of 6 mm in accordance with ASTM E8M standards, were cut perpendicularly to the welding directions (or the rolling direction for the base material) and sliced equally into three pieces (top, middle and bottom) in the thickness direction, and then machined to the required dimensions [26]. The gauge area of specimens was ground with SiC papers up to grit 600 along the loading axis to get rid of the cutting marks and to achieve a smooth surface [26] 3.3.4 Tensile properties and strain hardening behavior of FS W AA2219 Al Alloy:…”

Effect of Deformation Temperature, Strain Rate and Strain on the Strain Hardening Exponent of Copper/Aluminum Laminated Composites

“…Meanwhile, in order to satisfy the requirements of various industrial fields, thermal mechanical machining such as hot rolling and tension are necessary.However, there is little relevant research report [6,7]. Meanwhile, the strain hardening behaviours during the deformation process of Cu/Al laminated composites has not been investigated.On the other hand, sound bonding interface between copper and aluminum makes them as a whole and has unique characters during the isothermal compression of Cu/Al laminated composites, which is distinctly different from the deformation behaviour of copper alloy or aluminum alloy [8][9][10][11].…”