The Study on Heat Treatment Microstructure and Properties of Extruded Al-Mg-Si-Mn-Cr-Zr Alloy

Abstract In order to obtain a high-strength Al-Mg-Si aluminum alloy with tensile strength of more than 400MPa, trace amount Zr is added the 6082 an Al-1.0Mg-1.05Si-0.55Mn-0.15Cr-0.045Zr alloy. The mechanical properties and microstructure extruded were studied by performance test, metallography, scanning electron microscope (SEM), transmission (TEM), backscatter diffraction (EBSD) observation energy spectrum analysis. results show that, after 545°C×2h+170°C×8h heat treatment, has best properties. strength, yield elongation at break reached 423MPa, 402MPa 14%, respectively. strengthening mechanism mainly due large number dispersed needle-like β′ phases, sub-micron α-Al(MnCrFe)Si α-Al(MnFe)Si phases micron-level precipitated inside grains grain boundaries. precipitates phase, phase phase. After treated 545°C×2h+170°C×8h, β″ precipitations are uniformly in These can improve material. average size 7.41μm, bimodal structure composed low-angle boundaries high-angle formed.