AZ-31

Wrought magnesium alloy AZ31 with a thick section of 20 mm was prepared by squeeze casting (SC) and permanent steel mold casting (PSMC).The porosity measurements of the SC and PSMC showed that the SC AZ31 had a porosity of 1.13%, which was the 57% lower than that (2.66%) of the PSMC AZ31 counterpart.The microstructure analyses and phase identification indicated that the cast AZ31 alloy consisted of a primary α-Mg phase, eutectic Al-Mg-Zn phases and Al-Mg-Mn intermetallics.The fine primary α-Mg dendrites and a high amount of the intermetallic phase were present in the SC AZ31 alloy.The yield strength (YS), ultimate yield strength (UTS), elongation (ef), elastic modulus (E) and strain hardening rate of the cast AZ31 specimens were evaluated by tensile testing.The measured engineering stress vs. strain curves showed that the SC AZ31 alloy exhibited 49.5 MPa in YS, 194.3 MPa in UTS, 13.8% in ef, and 36.2 in modulus, while the YS, UTS, and ef of the PSMC AZ31 specimen were only 49.5 MPa, 173.1 MPa, and 9.2%.The results of the tensile testing evidently showed that the YS, UTS, ef, and E of the SC AZ31 alloy were 23%, 12%, 50%, and 24% higher than those of the PSMC counterpart.The calculated resilience and tensile toughness indicated that the SC AZ31 was more capable of resisting energy loads in elastic deformation and had an ability to absorb energy during plastic deformation without fracture than that of the PSMC AZ31.Also, the analyses of the true stress vs. strain curves revealed that, upon the onset of plastic deformation, the strain hardening rate of the SC AZ31 sample was 7,400 MPa, which was 10% higher than that (6,700 MPa) of the PSMC AZ31 specimen.The obtained mech. properties showcased the fit of the casting process to wrought magnesium AZ31 alloy, which was squeeze casting.The low porosity level, fine dendritic structure and a high content of intermetallic phase should be somewhat responsible for high mech. properties of the SC AZ31 alloy.