| In this paper, heat treatment effect on metallographic organization and performance of AZ91D and AZ31 magnesium alloy has been investigated. AZ91D magnesium alloy was treated by aging treatment, solution treatment and solution plus aging treatment. AZ31 magnesium alloy was treated by annealing treatment and deep cryogenic treatment. Observed the samples'metallographic structure, and tested their mechanical properties and the corrosion rate in NaCl solution. The experiment result showed:Aging treatment can improve AZ91D magnesium's corrosion resistance. Solid solution reduces the alloy'sβ(Mg17Al12) phase significantly and the hardness dropped dramatically. However the toughness increases from 6.23J/cm2 to 12.86J / cm2.And the corrosion resistance in NaCl solution reduces heavily, corrosion rate increases from 3.081mm / a up to 7.400mm / a, corrosion resistance decreased by 1.4 times. After aging and solid solution,β(Mg17Al12) phase re-precipitates, and its distribution is diffuse. The hardness and toughness is improved. Its corrosion resistance will remain basically unchanged.For the AZ31 magnesium alloy, the annealing treatment reduces its hardness, but its corrosion resistance is improved. Deep cryogenic treatment enables grain refinement. X-ray diffraction analysis shows that after deep cryogenic treatment the grain has produced a preferred orientation rotation. After 7 hours'deep cold treatment at -155℃AZ31 magnesium alloy's hardness and tensile strength are increased by 28.6% and 28.1%, but the corrosion rate from the rolling state of 4.862mm / rises up to 9.265mm / a. Corrosion resistance decreases by 90.6% as result. |
PDF Full Text Request