Effects Of The Heat Treatment On Microstructure And Properties In2026Al Alloys

The recent development trend of the addition of Zr in the Al alloyswas reviewed at home and abroad. The present paper designed the2026aluminum alloy with minor Zr, and the effects of added content of Zr on microstructure and machinability of Al-3.95Cu-1.32Mg-0.52Mn alloys was studiedto obtain the most suitable added content. By the heat treatment, the evolution rules of the microstructures and properties in2026alloys, in the different heat-treatment situation, were studied by the means of hardness test, room temperature tensile test, optical microscopy and electronic microscopy analysis. The main conclusions are as follows:(1) The refinement result of the Al-3.95Cu-1.32Mg-0.52Mn with0.11%Zr addition is comparatively better, and has no the coarse phase of Al3Zr. In2026Al alloys, a part of Zr element is solved in the Al matrix, and the remaining part is formed to be the phase of Al3Zr.(2) The more effective method of homogenization treatment is determined as420℃/8h+490℃/16h, then the alloys were hot rolled after staying warm for45min at450℃; The aim of two-stage homogenization is to obtain the fine precipitation of Al3Zr phase.(3) Compared with alloys homogenized at490℃only, the tensile strength and yield strength of two-stagehomogenized (420℃/8h+490℃/16h)2026Al alloys were raised23Mpa and12Mpa in the hot rolled state.(4) The reasonable solution treatment of2026Al alloys is to heat at498℃for2h, then quenched in water and aged at190℃(5) The room temperature (25℃) delayed has no obvious effect on the artificial peak aging hardness in Al-3.95Cu-0.52Mn-0.11Zr alloys, however, it can reduce the peak artificial aging hardness of Al-3.95Cu-1.32Mg-0.52Mn-0.11Zr alloys. When the presaging temperature is50℃, the pre-aging treatment is conductive to the improvementof peak artificial hardness in Al-3.95Cu-0.52Mn-0.11Zr alloys, however, it still has a negative effect on that of Al-3.95Cu-1.32Mg-0.52Mn-0.11Zr alloys. On conclusion, it had better to avoid the low temperature presaging treatment to obtain the better properties in2026Al alloys.