Effect of pre-homogenizing treatment on microstructure and mechanical properties of hot-rolled AZ91 magnesium alloys

Abstract

To improve the homogeneity and rolling formability of as-cast AZ91 magnesium, the effects of pre-homogenizing treatment on microstructure evolution, deformation mechanism, mechanical properties and tensile fracture morphology of hot-rolled AZ91 magnesium alloy were studied. The results showed that the amount of coarse β-Mg17Al12 phase decreases dramatically, being distributed along the grain boundaries as small strips after homogenizing. Twining plays a dominant role in the deformation mechanism of AZ91 alloys in the experimental condition, while dynamic recrystallization (DRX) considerably occurred in homogenized-rolled alloys, contributed to microstructure uniformity and β-Mg17Al12 phase precipitated refinement. The tensile strength of homogenized-rolled AZ91 alloys increases dramatically with elongation declining slightly in contrast to homogenized alloys. The fracture surface of homogenized-rolled specimen exhibits more ductile fracture with the manifestation of a large amount of dimples distributing higher density in matrix, while the micro cracks are prone to initiate around the Mg/Mg17Al12 phase interface and grain boundaries owing to the fragile interface bonding of two phases.

Enhancement of Mechanical Properties and Rolling Formability in AZ91 Alloy by RD-ECAP Processing

“…After post-ECAP rolling process, both of the UTS and YS are remarkably increased in these two rolled alloys, i.e., the C-ECAP + R and H-ECAP + R samples, of which the UTS are increased to 386 MPa and 366 MPa, respectively; and the YS are increased to 370 MPa and 337 MPa, respectively. In addition to the increased UTS and YS, the rolled alloys possess moderate ductility with elongation of ~7.2% and ~8.8%, respectively, which resemble the findings obtained by other researchers [41,42]. Indeed, some evidence on moderate elongation can also be found in Figure 5.…”

A Novel Approach to Fabricate Protective Layered Double Hydroxide Films on the Surface of Anodized Mg‐Al Alloy

“…Magnesium alloys also have a series of other advantages including good castability, good vibration and shock adsorption, recyclability, stiffness, and high damping capacity. Therefore, magnesium alloys are increasingly being utilized in automobile, aerospace, biomedical, architecture, and electronic industries . However, they are highly reactive and have poor corrosion resistance due to their lower electrode potentials, which is one of the major drawbacks limiting their applications at a larger scale.…”

Influence of Continuous Bending Process on Texture Evolution and Mechanical Properties of AZ31 Magnesium Alloy

“…9. It is well known that magnesium alloys are inclined to form of cleavage fracture or quasi-cleavage fracture due to their limited slip systems [1,36,37]. As can be seen in Fig.…”

“…As the lightest metal structural materials, magnesium alloys are of great interest in the 3C, transportation and aerospace industries due to their low density, high specific strength, high specific stiffness, recyclability and so on [1][2][3]. However, magnesium alloy sheets exhibit poor ductility and formability at ambient temperature due to their hexagonal close-packed (HCP) crystal structure, which hinder their widespread industrial applications.…”