Thermal Simulation Of Al-mg-sc Alloys And Low Temperature Performance And Corrosion Behavior

Al-5.8Mg-0.3Mn-0.2Sc-0.12Zr alloy ingot was made by the method of ingot metallurgy. This alloy was treated by homogenization, hot rolling, and then cold rolling to board with 2.2 mm thickness. The flow stress behavior during isothermal compression, the tensile property of low temperature and the corrosion behaviors of alloy was studied. The conclusions can be summarized as follows:(1) During hot compression deformation of the alloy, the flow stress increases with increasing strain and fall down after a peak value, then tends to be constant. The peak value increases with the test temperature's reduction and strain rate's increase.(2) The alloy's four characteristic constant were obtained as follows: stress exponent n=5.71, stress level parameterα=0.0088, structure factor A=2.1×10¹⁰, deformation activation energy Q=151.27KJ/mol. So, under the deformation condition, the relation of the flow stress, strain rate and the deformation temperature is showed as follows:(3) The main softening mechanism during hot compression deformation of the alloy is dynamic recovery. Under some conditions, the alloy can show continuous dynamic recrystallization. The critical conditions of dynamic recrystallization of the alloy are calculated to be:(4) Tensile strength of Al-Mg-Sc alloy board markedly increases with the test temperature's reduction. This is main because that with the temperature's reduction, short distance resistance of dislocation increases rapidly, and then the yield strength increases.(5) Al-Mg-Sc alloy board's elongation under low temperature deformation is not lower, but higher than room temperature's. The obstruction of plane glide during low temperature deformation is the main reasons for low temperature plasticity's improve. (6) In the different stability annealing temperature, the resistance to intergranular corrosion of the Al-Mg-Sc alloy increases with the increasing annealing temperature. Descending order of the intergranular corrosion sensibility of the alloy is: unannealed> 130°C/lh>230°C/lh> 340℃/1h>500℃/1h.(7) In the different stability annealing temperature, the resistance to exfoliation corrosion of the Al-Mg-Sc alloy increases firstly, then decreases and reaches the best at 340℃with the increasing annealing temperature. Descending order of the exfoliation corrosion sensibility of the alloy is: unannealed> 130℃/1h>230℃/1h>500℃/1h>340℃/1h.(8) The resistance to exfoliation corrosion and intergranular corrosion of the Al-Mg-Sc alloy decrease firstly and then increase secondly with the increasing annealing time at the annealing temperature 130℃. Descending order of the corrosion sensibility of the alloy is: 130℃/12h> 130℃/24h>130℃/4h>130℃/1h.(9) The resistance to stress corrosion of Al-Mg-Sc alloy is strong.