Evaluation of Microstructure and Mechanical Properties of 5182 Aluminum Alloy Ingots with Large-Sections

Abstract

ABSTRACT The microstructure and mechanical properties of continuously-cast 5182 aluminum alloy ingots with large-sections are not uniform，which depends on the diameter of ingots and the position where the sample locates. For the Φ160 ingot, the outer layer and middle layer have fine and uniform α-Al grains, while the centre appears the coarse α-Al dendrite. In contrary, the middle and centre layers appear the coarse α-Al dendrite, only the outer layer has the fine α-Al grains for the Φ380 ingot. The (FeMn)Al 6 and Mg 2 Si phases coexist in the primary α-Al grain boundaries and the Mg 2 Al 3 phases precipitate in the α-Al grains. By homogenously annealing, the Mg 2 Si and (FeMn)Al 6 phases are broken-up into dispersive islands and particles and the Mg 2 Al 3 phases precipitate more sufficiently in the forms of fine particles and short flakes. The elongation is largely enhanced; while the yield strength, tensile strength and hardness receive much less influence by the heat treatment. However, the homogenous annealing at 495 o C for 24 h is not enough for adjusting the microstructure of the Φ380 ingot.