钎焊后自然时效对3003/6xxx/3003复合铝合金性能和组织的影响

以6xxx系铝合金为芯材,3003铝合金为两侧皮材,经熔炼、铸造、复合、热轧、冷轧及成品退火制备了厚度为1.5 mm的3层复合铝合金。在600 ℃下模拟钎焊,经空冷后进行1、5、10、15、20、25、30 d的自然时效。结果显示：复合铝合金的强度、维氏硬度在自然时效初期快速增加,20 d后上升缓慢,30 d时抗拉强度、屈服强度、芯材维氏硬度达到最大,分别为242.3 MPa、122.9 MPa、84.0;芯材晶粒尺寸钎焊后较钎焊前略微长大,经不同自然时效时间的芯材晶粒平均尺寸大小相当,表明自然时效不改变芯材晶粒的大小;钎焊后以及经自然时效之后芯材中标识出的第二相为不规则的AlFeSiMnCu相。

Effects of the natural aging time after brazing on properties and microstructures of 3003/6xxx/3003 cladding aluminum alloy

Taking 6 xxx series aluminum alloy as core material and 3003 aluminum alloy as coating material on both sides, three layer cladding aluminum alloy with thickness of 1.5 mm was prepared by melting, casting, cladding, hot rolling, cold rolling and annealing. Natural aging was carried out for 1, 5, 10, 15, 20, 25, 30 d with air cooling by computational simulations of the brazing process at 600 ℃, respectively. The results show that the strength and hardness of the cladding aluminum alloy increase rapidly at the initial stage of natural aging, then slowly increase after 20 d. At 30 d, the tensile strength, yield strength and core Vickers hardness reach the maximum of 242.3 MPa, 122.9 MPa and 84.0, respectively. The average grain size of the core material after brazing increase slightly, and remains with different natural aging time after brazing, indicating that the natural aging does not change the grain size of the core material. The secondary phase identified in the core material after brazing and natural aging is irregular AlFeSiMnCu phase.