摘要
The effect of rolling to a total effective strain of 2 at the liquid nitrogen temperature and subsequent natural and artificial aging on the structure and service properties of the pre-quenched hot-pressed 2024 aluminum alloy was investigated.Using optical and electron microscopy,and X-ray analysis,it was found that the cryorolling did not qualitatively change the type of the initial coarse-fibered microstructure,but produced a well-developed nanocell substructure inside fibers.Further aging led to decomposition of the preliminary supersaturated and work-hardened aluminum solid solution and precipitation of strengthening phases in the statically recovered and/or recrystallized matrix.As a result,the rolled and naturally aged alloy demonstrated the yield and ultimate tensile strengths(YS=590 MPa,UTS=640 MPа)much higher than those in the pressed andТ6-heat treated alloy at equal elongation to failure(El^6%).Artificial aging at a temperature less than conventional T6 route could provide the extra alloy strengthening and the unique balance of mechanical properties,involving enhanced strength(YS=610 MPa,UTS=665 MPа)and ductility(El^10%),and good static crack resistance(the specific works for crack formation and growth were 42 and 18 k J/m^2,respectively)and corrosion resistance(the intensity and depth of intercrystalline corrosion were 23%and 50μm,respectively).
在液氮温度和应变为2条件下对预淬火热压2024铝合金进行轧制,研究轧制和后续天然和人工时效对其结构和服役性能的影响。利用光学显微镜、电子显微镜和X射线分析发现,深冷轧制并没有定性地改变最初粗纤维组织的类型,而是在纤维内部产生发育良好的纳米晶胞亚结构。进一步时效导致初步过饱和、加工硬化铝固溶体的分解,也导致静态回复和/或再结晶基体中强化相的沉淀。相比于压制和Т6热处理态的合金,轧制和自然时效态的合金表现出更高的屈服强度(YS=590 MPa)和极限抗拉强度(UTS=640 MPа),而两种合金的断裂伸长率相当(El^6%)。低于常规T6路线温度的人工时效可以进一步提高合金的强度且保持良好的综合力学性能,包括较高的强度(YS=610MPa,UTS=665MPа)与延性(El^10%)、良好的静态裂纹阻力(裂纹形成和生长功分别为42和18k J/m^2)和良好的耐腐蚀性(晶间腐蚀的强度和深度分别为23%和50μm)。
作者简介
Corresponding author:Stanislav KRYMSKIY,Tel:+7(347)282-38-56,E-mail:stkr_imsp@mail.ru
