| 3000 aluminum alloy is widely used in automotive air conditioning radiator as the key material in vehicle light-weighted, because of its excellent specific strength, corrosion resistance and formability. The compressive deformation behavior of Al-Mn-Si-X alloy during compression at elevated temperature and changes of microstructure was studied by isothermal hot compression on Gleeble-1500. The deformation temperature range from 350℃to 500℃and the strain rate range from 0.01s-1 to 20s-1. The relationship between flow stress and strain rate, deformation temperature and deformation degree of Al-Mn-Si-X alloy during compression at elevated temperature had been studied, and the flow stress model had been established. Microstructure evolution of Al-Mn-Si-X alloy during compression at elevated temperature had been analyzed by using optical microscope(OM), transmission electron microscope(TEM). The mechanical properties of continuous extrusion tube had been analyzed by tensile test and scanning electron microscopy(SEM).(1) The flow stress of new Al-Mn-Si-X alloy during compression at elevated temperature depends strongly on the strain rate and deformation temperature. The results show that the true stress-true strain curves exhibit a peak stress at critical strain, after which the flow stresses decrease monotonically until high strains. Flow stress depends on strain rate and deformation temperature. Flow stress is in inverse proportion to deformation temperature while it is in direct proportion to strain rate. The peak stress level decreases with increasing deformation temperature and decreasing strain rate, which can be represented by the Zener-Hollomon parameter Z in the hyperbolic sine equation with the hot deformation activation energy of 159.2kJ/mol.(2) Microstructure evolution of new Al-Mn-Si-X alloy during compression at elevated temperature has been analyzed by OM and TEM, with lnZ value decreasing, the fibrous tissue trend to grow up, dynamic recovery and dynamic recrystallization occurs; dislocation density decreases gradually; subgrain dimension trends towards increase; the main soften mechanisms of the alloy transforms from dynamic recovery to dynamic recrystallization. The main dynamic recrystallization is geometric dynamic recrystallization(GDRX), have also taken place in continuous dynamic recrystallization(CDRX). (3) Tensile properties of Al-Mn-Si-X alloy extruded tube during tension test has been analyzed by SEM. With the decrease of Si content, tensile strength trend to grow up, elongation tends to decrease and plastic decline; The main fracture mode is ductile fracture. |
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