Microstructure and Properties of an АА 2139 Alloy Welded Joint Produced by Linear Friction Welding

Abstract

Microstructure and mechanical properties of a solid-phase joint produced by linear friction welding of AA2139 alloy samples have been studied. It has been shown that the weld formed as a result of LFW of two rectangular-shaped samples does not have macroscopic defects and has a high strength. It has been that the microstructure transforms significantly in the weld line during plastic deformation and deformation heating.

Linear Friction Welding of a Commercial Aluminum Alloy

“…However, the zone length is 2.0 -2.5 mm, which is less than in samples after LFW of D16T, where this value was 4 -5 mm [3,13]. Fine equiaxed grains are observed in the structure of this zone, mainly along the boundaries of initial coarse grains, which were also observed in D16T after LFW [3,14]. Grains with a size of about 4 -8 µm are observed in the weld zone (Fig.…”

“…The analysis of the microstructure evolution during LFW of the AA2139 alloy with the results obtained previously in [14] allows evaluating the impact of geometrical parameters connected with dimensions of welded surfaces and time of heating and cooling during LFW. In [14] the friction Materials Engineering and Technologies for Production and Processing II duration during LFW of samples with a section 26х13 mm from the AA2139 alloy in the state identical to State 2 was only 1.3 sec. This is almost three times less than it was during the current studies performed on samples of 80×25 mm (3.5 s.).…”

“…Both contact zone increase during LFW of samples and increase of the heating time and growth of the weight of a billet heated (heated zone volume) during LFW significantly effect the length and structure of zones typically identified during LFW. Thus, for example, grain boundaries are not revealed by etching in samples with a section of 26х13 [14], which testifies to a much higher level of hardening of the microstructure during plastic deformation and smaller sizes of fragments, which form during recrystallization processes during LFW of the AA2139 alloy. The microhardness measurements on the samples after LFW conducted across the weld seam line are displayed in Fig.…”

“…The authors of works [11,12] presented the modeling results for LFW of samples from AA2024 and AL-Cu-Mg alloys. Possibility of defect-free weld joint production from D16 and 2139 alloy of the Al-Cu-Mg system by the LFW technique is described in papers [13,14].…”

“…Thus, it can be very attractive to get major progress in using Al alloys to produce a first-stage of gas-turbine compressor. In [14] possibility for producing weld joints of this alloy with a high level of strength was shown. However, introduction of the technology into production of real items requires the impact of the initial structure, sample sizes, welding regime parameters on properties of weld joints to be studied.…”