The influence of welding parameters on macrostructure and mechanical properties of Sc-modified AA2519-T62 FSW joints

Abstract

In this investigation, a 5 mm thick extrusion of AA2519-T62 alloy has been welded using friction stir welding method. The various sets of process parameters have been involved within the range of 400–1200 rpm tool rotation speed and 100–800 mm/min welding speed. Selected joints have been subjected to the macrostructure analysis, microhardness measurements, tensile and low cycle fatigue testing (at ε = 0.3%), and fractography analysis. It has been stated that imperfection-free macrostructure is obtained for welds produced with lowest welding speed: 100 mm/min and tool rotation speed within the range of 400–800 rpm. The highest joint efficiency (85%) has been obtained for the sample characterized by the presence of voids in the upper part of the stir zone. Considering macrostructure analysis and established mechanical properties of the joints, it may be concluded that the best set of welding parameters for AA2519-T62 is within the range of 600–800 rpm tool rotation speed with welding speed of 100 mm/min for used MX Triflute tool.

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

“…The type of tool used was an MX Triflute (ESAB, Gothenburg, Sweden) and the tilt angle was set to 2°. These parameters were selected based on the previous study performed by authors [ 34 ]. The obtained joint was sectioned perpendicular to the welding direction.…”

“…Vuherer et al analyzed fatigue behavior of AA2024 T-351 aluminum alloy sheets joined by FSW with various parameters and based on the results they described the relationship between welding velocity and basic fatigue properties focusing on the issue of heat input and coarse of microstructure [ 32 ]. Based on our own research, we can state that post-weld heat treatment decreases the fatigue strength of AA2519 FSW joints significantly [ 33 ] and the optimal welding parameters for welding of AA2519-T62 lie within the range of 600–800 rpm tool rotation speed and 100 mm/min welding velocity, giving relatively high joint efficiency (around 80%) and good fatigue properties [ 34 ]. Considering the issue of high complexity, which is evident in the behavior of FSW joints during cyclic loading in the low cycle fatigue regime, a number of factors have to be taken under examination, susceptible to the high plastic strain amplitude (e.g., heat-affected zone, low-hardness zone, stir zone/thermo-mechanically affected zone interface) [ 34 , 35 , 36 , 37 ].…”

“…Based on our own research, we can state that post-weld heat treatment decreases the fatigue strength of AA2519 FSW joints significantly [ 33 ] and the optimal welding parameters for welding of AA2519-T62 lie within the range of 600–800 rpm tool rotation speed and 100 mm/min welding velocity, giving relatively high joint efficiency (around 80%) and good fatigue properties [ 34 ]. Considering the issue of high complexity, which is evident in the behavior of FSW joints during cyclic loading in the low cycle fatigue regime, a number of factors have to be taken under examination, susceptible to the high plastic strain amplitude (e.g., heat-affected zone, low-hardness zone, stir zone/thermo-mechanically affected zone interface) [ 34 , 35 , 36 , 37 ]. LCF is important from the point of view of estimating the durability of structural elements at the design stage of the structure, during its operation, as well as in the analysis of the assessment of the structure life (and the possibility of its extension).…”

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

“…In recent years, friction stir welding (FSW) has been introduced as a very efficient technology in joining aluminum alloys in solid state by the local stirring of a plasticized material from both elements to be welded [ 7 , 8 , 9 ]. The overall performance of aluminum alloy FSW joints is very good, but when it comes to the precipitation-hardened alloys (2XXX and 7XXX series), a reduction in mechanical properties is inevitable [ 8 , 10 , 11 , 12 ]. The reason is directly concerned with unfavorable evolutions of the strengthening phase undergoing during a thermal cycle of the welding process [ 13 ].…”

Study on the weldability of AA2519 armor grade aluminium alloy

“…These additions cause grain refinement (during solidification -casting or welding), increase in strength (due to presence of nano-precipitates), and increase in temperature of recrystallization and grain growth (by pining of grain boundaries) [2][3]. This version of the alloy is the subject of series of investigations at the Military University of Technology (MUT) including explosive welding [4] and post-processing [5], friction stir welding [6][7][8], and laser beam welding. The joining of AA2519 causes some problems including two major ones of metallurgical and of technical nature.…”