Effect of different initial tempers on creep aging behavior of 2195 aluminum-lithium alloy

Five kinds of 2195 aluminum-lithium alloys with different initial tempers were obtained through different heat treatment methods. The creep aging test with a constant stress of 140 MPa, at 180 °C, mechanical tensile test at room temperature and the scanning electron microscope (SEM) observation were used to study the dependence of microstructure and properties on the initial tempers of 2195 aluminum-lithium alloy under creep aging forming conditions. The results show that the creep deformation of the alloy with re-solution initial temper is the largest, followed by the solid solution, over-aging and peak aging tempers, while the aged alloy with the regression temper has the smallest creep deformation. The order of yield and tensile strength from high to low is re-solution > solid solution > peak aging > over-aging > regression treatment. The order of elongation to fraction from large to small is solid solution > re-solution > peak aging > over aging > regression treatment. Finally, the high-strength and ductility mechanism of the creep-aged alloy with the re-solution temper was revealed: uniformly distributed fine strengthening phase (T1 phase) within the grain and narrowed precipitation-free zone at grain boundaries.