Research on the Properties and Low Cycle Fatigue of Sc-Modified AA2519-T62 FSW Joint

Abstract

The aim of this research was to examine the mechanical and fatigue properties of friction stir welded Sc-modified 5 mm thick AA2519-T62 extrusion. The joint was obtained using the following parameters: 800 rpm tool rotation speed, 100 mm/min tool traverse speed, 17 kN axial, and MX Triflute as a tool. The investigation has involved microstructure observations, microhardness distribution analysis, tensile test with digital image correlation technique, observations of the fracture surface, measurements of residual stresses, low cycle fatigue testing, and fractography. It was stated that the obtained weld is defect-free and has joint efficiency of 83%. The failure in the tensile test occurred at the boundary of the thermo-mechanically affected zone and stir zone on the advancing side of the weld. The residual stress measurements have revealed that the highest values of longitudinal stress are localized at the distance of 10 mm from the joint line with their values of 124 MPa (the retreating side) and 159 MPa (the advancing side). The results of low cycle fatigue testing have allowed establishing of the values of the cyclic strength coefficient (k′ = 504.37 MPa) and cyclic strain hardening exponent (n′ = 0.0068) as well as the factors of the Manson–Coffin–Basquin equation: the fatigue strength coefficient σ′f = 462.4 MPa, the fatigue strength exponent b = −0.066, the fatigue ductility coefficient ε′f = 0.4212, and the fatigue ductility exponent c = −0.911.

Effect of Welding Parameters on Mechanical Properties and Microstructure of Friction Stir Welded AA7075-T651 Aluminum Alloy Butt Joints

“…Compared to the base material, the tested joints have generally smooth fracture surfaces ( Figure 9 c,e). In both samples, the fracture mechanism is dominated by a transgranular ductile rupture, which is reflected in the mixed participation of large and fine dimples ( Figure 9 d,f) [ 40 ]. The locations of failure in these two samples are the same and the only difference is their microhardness: 100–105 HV0.1 in the case of S10 and 115 HV0.1 for F4.…”

The Influence of Tool Shape and Process Parameters on the Mechanical Properties of AW-3004 Aluminium Alloy Friction Stir Welded Joints

“…During the tests, it was observed that pin shape had a significant impact on the appearance of the joint produced as more material outflow on the retreating side of the joint was seen in joints made with the cylindrical threaded pin. Material outflow is a common defect [24,35,55]. The amount of outflow is associated with the shape of the pin and the process parameters [17,21,24].…”

Induction Assisted Hybrid Friction Stir Welding of Dissimilar Materials AA5052 Aluminium Alloy and X12Cr13 Stainless Steel

“…The insufficient tool rotation speed (600 rpm) cause the settling of large X12Cr13 SS particles in the retreating side of the weldment and thereby reduces the joint strength. Also, this leads to the propagation of fracture along with the bimetallic interface in the nugget zone [20]. The lack of material movement is visible in the joint produced by 600 rpm due to the insufficient heat generated by the tool.…”