喷射成形7055高强铝合金的热处理工艺优化及其应用

基于两次挤压处理后的喷射成形7055铝合金,采用SEM、光学显微镜、硬度仪和拉伸试验机等分析手段研究了试验合金在不同时效工艺下的组织和性能。结果表明,相较于单级时效工艺,经过120 ℃×6 h+160 ℃×2 h双级时效处理后,析出相呈短棒状均匀分布于基体,其沿长度方向上的平均尺寸为500 nm,宽度方向平均尺寸为10 nm,时效峰值硬度达196.4 HV0.05。采用双级时效工艺处理的试验合金在298、398、498和598 K的抗拉强度分别为855、792、688和360 MPa,断后伸长率分别为14%、11%、9%和8%。采用该双级时效处理工艺处理的喷射成形7055铝合金应用于轮毂紧固件产品的制备,并对其进行硫酸阳极氧化处理,可使得紧固件试样同时兼具高强度、高硬度以及高耐蚀性能,有望得到更广泛的应用。

Optimization of heat treatment process of spray-formed 7055 high strength aluminum alloy and its application

Based on the spray-formed 7055 aluminum alloy after twice extrusion treatment, the microstructure and properties of the tested alloy under different aging processes were studied by means of SEM, optical microscope, hardness tester and tensile testing machine. The results show that compared with the single-stage aging process, after two-stage aging treatment at 120 ℃ for 6 h and at 160 ℃ for 2 h, the precipitates are uniformly distributed in the matrix with shape of short rod, which the average size along the length and width direction is 500 nm and 10 nm, respectively, and the aging peak hardness is 196.4 HV0.05. The tensile strength of the tested alloy treated by two-stage aging process at 298, 398, 498 and 598 K is 855, 792, 688 and 360 MPa, respectively, and the elongation after fracture is 14%, 11%, 9% and 8%, respectively. The spray-formed 7055 aluminum alloy treated by the two-stage aging treatment process is applied to the preparation of hub fastener products, and is subjected to sulfuric acid anodizing treatment, which can make the fastener specimens have high strength, high hardness and high corrosion resistance at the same time, and it is expected to be more widely used.