Stir zone material flow patterns during friction stir welding of heavy gauge AA5056 workpieces and stability of its mechanical properties

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 4 2021 Fig. 8. Structure of samples 2.4 ( а , b ) and 2.5 ( c, d ) in the tool outlet zone, cut in the horizontal section according to the scheme shown in Fig. 1 а c b d Fig. 9. Change of microhardness measured according to the scheme shown in Fig. 2 in the stir zone and near-weld zone main structural zones also show the absence of signi fi cant hardening of the material and slight differences in the hardness values in the different thickness sections of the joint. Thus, scatter of microhardness values on the whole sample is essential (from 745 to 1045 MPa, i.e., 40 % from the minimum value), which is much higher than an increase of microhardness in the central part of the stir zone (from 745 to 975 MPa or 31 % from the minimum value) concerning microhardness of base metal.