Effect of Mg Content on Vibration Fracture Resistance of Friction Stirred Al–Mg Alloys

Abstract

In this study, the effect of Mg content on friction stirred Al-Mg alloy is discussed, and the experimental results indicate that grains of parent plate which are refined through FSP (friction stir processing) are effective in enhancing tensile properties of materials through FSP and improving the vibration fracture resistance of friction stirred specimens. It should be noted that the deterioration of vibration fracture resistance can be recognized as Mg content increases, the grain size actually has been refined by FSP. From crack propagation result, an intergranular crack propagation feature can be recognized in the specimen with higher Mg content, and it is reasonable to suggest that the precipitation of phase plays an important role in the deterioration of vibration fracture resistance. However, all cross-sectioned microstructures at stir zone show that distinct finer grains which can be acquired by dynamic recrystallization during FSP. That meaningful improvement of uniform elongation on friction stirred specimens can be recognized is not only resulted from controlling the grain size factor, but also microstructural characteristics factor which are resulted from high temperature shear deformation.

Microstructures and high temperature mechanical properties of friction stirred AZ31–Mg alloy

“…The friction stir process (FSP) [1][2][3][4] is an innovative process that developed from friction stir welding (FSW) [5,6]. FSP was adopted in this study because its friction rotation between the tool and specimen can produce a plastic deformation flow to obtain finer recrystallized grains and improve the material characteristics.…”

Vibration fracture resistance of 5052H112 aluminum alloy processed by cold rolling and friction stirring

“…The D-N curves also show a distinct plateau stage of maximum deflection in-between the initial ascending stage and the final descending stage, except for H112 and FS specimens. Based on our previous investigation [9], the deflection amplitude dropping from its peak indicates a deviation of the actual vibration frequency from the resonant frequency. Therefore, the vibration life in this study as shown in Fig.…”

“…The 5052 alloys processed by hot rolling (H112) and subsequent friction stirring using a best set of fixed FS parameters were compared with those processed by cold rolling with various rolling reductions. Based on previous experimental results [9,10], the vibration fracture resistance depends on vibration test conditions and material characteristics, respectively. The major difference between hotrolled and cold-rolled specimens is the microstructural feature, which depends mainly on the imposed prior strain.…”