铸锭均火冷却速度对6061铝合金组织与性能的影响

Effect of homogenization cooling rate on the microstructure and properties of 6061 aluminum alloy billets

采用光学显微镜、扫描电子显微镜观察组织,常温拉伸力学性能、布氏硬度和电导率等测试方法,试验研究了6061铝合金铸锭均匀化后冷却速度对其显微组织、力学性能和电导率的影响。结果表明,与均匀化后风冷冷却的铸锭相比较,均匀化后随炉冷却的铸锭晶界处有明显的粗大化合物,尺寸可达15μm,该粗大化合物在后续挤压生产中难以破碎溶解;均匀化后随炉冷却的铸锭相比于风冷却铸锭生产的挤压型材强度值与硬度值较低,但断后伸长率与电导率较高。

The effects of homogenization cooling rate on the microstructure, mechanical properties and conductivity of 6061 aluminum alloy billets were investigated by optical microscopy （OM）, scanning electron microcopy （SEM）, tensile test at room temperature, Brinell hardness and whirlpool conductivity analysis. The results show that the billet cooling down with furnace with slow cooling rate after homogenization, compared with the blast-cooled billet with fast cooling rate, is prone to form the coarse cluster of equilibrium phase, whose size approaches 15μm along the grain boundary. It is difficult to be broken and dissolved during the extrusion process. The billets with slow cooling rate can lead to lower strength and Brinell hardness but higher elongation and conductivity of profiles, compared with the billet with fast cooling rate.