| Al-Mn-Zn-X Alloy belongs to the A1-Mn series which strength can not be improved by heat treatment. A1-Mn series alloys is widely used in chemical equipment, civil hardware and air-conditioning with good corrosion resistance, formability, high ductility, well electric and thermal conductivity, excellent specific strength, corrosion resistance and formability. The flow stress behaviors of Al-Mn-Zn-X aluminum alloy were studied by compression test at the deformation temperature ranges from 350℃to 500℃and the strain rate ranges from 0.01s-1 to 10s-1 on Gleeble-1500 system. The relationship of flow stress, strain rate, deformation temperature and deformation degree were studied by compression test of Al-Mn-Zn-X aluminum alloy at high temperature, and the flow stress model was identified. Microstructure evolution of Al-Mn-Zn-X alloy was studied by optical microscopy (OM) and transmission electron microscopy (TEM). The mechanical properties of continuous extrusion tube were analyzed by tensile test and scanning electron microscopy(SEM).The results showed that the strain rate and deformation temperature had obvious effects on the flow stress of Al-Mn-Zn-X alloy during compression at high temperature. the true stress-true strain curves exhibited a peak stress at critical strain. The flow stress decreased monotonically until high strains after reaching the peak stress by dynamic recovery. The peak stress level decreased with the increasing of deformation temperature and decreasing of strain rate, which can be represented by the Zener-Hollomon parameter Z. In the hyperbolic sine equation the hot deformation activation energy was 171.638kJ/mol. It was found that with the increasing of strain rate the thermal effect became more significant. The correction of flow stress for deformation heating at high strain rates was accomplished for the precision of the constitutive equation.The deformation microstructures of Al-Mn-Zn-X aluminum alloy at high temperature compression were evaluated by LnZ. The dynamic recovery was the dominative restoring mechanism with high LnZ value; the main soften mechanisms of the alloy transform from dynamic recovery to geometric dynamic recrystallization (GDRX) with lnZ value decreasing; discontinuous dynamic recrystallization(CDRX) was found in some deformation condition.The grain size of Al-Mn-Zn-X Alloy extruded tube by CONFORM process was small. The result showed that CONFORM process can refine grains. The fracture mode of Al-Mn-Zn-X Alloy tube was dimple-coalescence fracture. The Al-Mn-Zn-X Alloy extruded tube by CONFORM process had great plasticity. The elongation was above 29% and the tensile strength was above 126MPa. |
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