Regularities of Friction Stir Processing Hardening of Aluminum Alloy Products Made by Wire-Feed Electron Beam Additive Manufacturing

Friction stir processing of additive workpieces in the sample growth direction (the vertical direction) and the layer deposition direction (the horizontal one) was carried out. The hardening regularities of aluminum-silicon alloy A04130 and aluminum-magnesium alloy AA5056 manufactured by electron beam additive technology were studied. For each material, 1 to 4 subsequent tool passes were performed in both cases. It was found that the formation of the stir zone macro-structure does not significantly change with the processing direction relative to the layer deposition direction in additive manufacturing. The average grain size in the stir zone after the fourth pass for AA5056 alloy in the horizontal direction was 2.5 ± 0.8 μm, for the vertical one, 1.6 ± 0.5 μm. While for the alloy A04130, the grain size was 2.6 ± 1.0 μm and 1.8 ± 0.7 for the horizontal and vertical directions, respectively. The fine-grained metal of the stir zone for each alloy in different directions had higher microhardness values than the base metal. The tensile strength of the processed metal was significantly higher than that of the additively manufactured material of the corresponding alloy. The number of tool passes along the processing line is different for the two selected alloys. The second, third and fourth passes have the most significant effect on the mechanical properties of the aluminum-magnesium alloy.