Abstract:The microstructure and mechanical properties of 105 mm thick 5083 aluminum alloy hot rolled plate were investigated by metallurgical microscope, scanning electron microscope and tensile testing machine, and three major characteristic problems in mechanical properties inhomogeneity were explained. The results show that the mechanical properties of the rolled plate are inhomogeneous along the thickness direction. From the surface to the center, the strength shows an inverted “N” shape change and the elongation presents a semi “U” shape change. Several similar structural units composed of long fibrous grains (LFG) and short fibrous grains bands (SFGB) exist in a special layer (Layer 2) adjacent to the surface. This alternating layered distribution of LFG and SFGB is conducive to improving the plasticity by dispersing the plastic deformation concentrated on the boundary line (BL) between them. However, their different deformability will cause the alternation of additional stresses during the hot rolling, leading to the strength reduction. The closer the location to the center of the plate is, the more likely the recovery rather than the recrystallization occurs. This is the possible reason for the unnegligible difference in strength near the central region (Layer 4 and Layer 5).

Key words: aluminum alloy thick plate; mechanical properties; inhomogeneity; fibrous grains; dynamic recovery; dynamic recrystallization