再生7050铝合金热处理工艺研究

Heat Treatment Process of Recycled 7050 Aluminum Alloy

利用光学显微镜、直读光谱仪、万能试验机等手段,研究了再生7050铝合金铸锭均匀化热处理、板材固溶及时效处理工艺。结果表明,再生7050铝合金中主元素Cu、Mg、Zn偏析率均保持在8%以下,低倍组织无裂纹、气孔等铸造缺陷;铸锭经470℃×20 h的均匀化热处理后,晶界处非平衡凝固条件下形成的共晶组织消失;板材经过475℃×0.5 h的固溶处理后,晶界处第二相回溶较彻底,伸长率达到34%;再经过120℃×24 h的时效处理后,晶内弥散析出颗粒状析出相,板材的力学性能达到最高,其中抗拉强度为608 MPa、屈服强度为539 MPa,同时伸长率为17.5%。

The homogenization heat treatment for ingots,solid solution and aging treatment for plate of recycled 7050 aluminum alloy were investigated by optical microscope,direct reading spectrometer,universal testing machine and other experimental methods.The results indicate that the segregation rates of the main elements Cu,Mg,and Zn in the recycled 7050 aluminum alloy remains below 8%,absence of casting defects including cracks and pores in the macrostructure.After homogenization heat treatment of the ingots at 470℃for 20 h,eutectic structure generated under non-equilibrium solidification conditions at the grain boundary diappears.After solution treatment of the plate at 475℃for 0.5 h,the second phases at grain boundary are completely dissolved,where the elongation reaches 34%.Then after aging treatment at 120℃for 24 h,granular precipitates are precipitated dispersedly in the grains,and the mechanical properties of plate present satisfied effect,where the tensile strength,yield strength and elongation reach 608 MPa,539 MPa and 17.5%,respectively.