Microstructural evolution of 2519-T87 aluminum alloy obliquely impacted by projectile with velocity of 816 m/s

Target made of 2519-T87 aluminum alloy was obliquely impacted by a projectile. Microstructural evolution around the crater was investigated by optical microscopy （OM）, transmission electron microscopy （TEM）, and electron backscattered diffraction （EBSD）. The micro-hardness distribution near the crater after impact was studied. The results indicate that at the entering stage, the amount of adiabatic shear band （ASB） is the most, and the precipitates are as fine as those of the target material; the micro-hardness is higher than that at the other stages. At the stable-running stage, the amount of ASB reduces as the micro-bands increase; the precipitates tend to coarsen, which leads to the decrease of the micro-hardness. At the leaving stage, there is a large amount of micro-bands; the precipitates are refined, and the micro-hardness is higher than that at the stable-running stage. The difference in the micro-hardness of the impact stages is due to work hardening and precipitate coarsening, which is caused by adiabatic temperature rise in the alloy.

2519-T87装甲铝合金及其焊接性

介绍了一种新研制的、具有优良力学性能和抗弹性能的、适用于轻型装甲车辆的2519-T87铝合金。系统地研究了该合金的拉伸性能、断裂韧性、疲劳性能、抗弹和耐腐蚀性能。为了充分使用该合金,重点对其与自身及目前正在使用的装甲铝合金的焊接性进行了评价。试验结果表明:2519-T87本身是可焊的,并可与5083-H131进行焊接;同时还对多种填充金属、焊接参数及焊后热处理也进行了研究,以确定其对焊件力学性能、热裂敏感性、显微组织以及抗弹性能的影响。

高强铝合金的激光-MIG复合焊接的实验研究

以20 mm厚的高强铝合金2519-T87为研究对象,研究了激光-MIG复合焊接工艺的工艺参数、坡口形貌以及热处理制度对高强铝合金的平板对接接头的抗拉强度的影响。研究表明:采用类似双U型坡口比国外常用的双V型坡口更有利于复合焊的焊接;保护气体对焊接接头的气孔的形成比较敏感,从而影响焊接接头的抗拉强度,复合焊的保护气体一般采用He气中添加少量的Ar;送丝速度通过改变焊接热输入来影响焊缝组织的晶粒大小以及强化元素的烧损量对焊接接头的强度影响较大。焊后对接头进行合适的热处理,可以显著提升接头的抗拉强度。

高强铝合金的MIG焊焊接工艺

采用自行研制的焊丝对2519-T87高强铝合金进行了熔化极气体保护焊(MIG)焊接,研究了焊丝成分和焊接热输入对接头组织和力学性能的影响。结果表明:采用自行研制的3种焊丝焊接接头的抗拉强度均超过了美国的ER2319焊丝,其中采用8#丝的接头焊缝组织最为细小,可获得最高的接头抗拉强度,且随着焊接热输入的减小,焊缝中二次枝晶之间的间距随之减小,Cu元素的偏析程度随之减弱,接头的力学性能得到提高。