退火温度对5052/AZ31B爆炸复合板组织与性能的影响

Effect of Annealing Temperature on Microstructure and Properties of 5052/AZ31B Explosive Composite Plate

将5052/AZ31B爆炸焊接复合板在300℃、350℃及400℃下进行退火处理,并研究了退火前后复合板的组织和性能。结果表明:退火过程中镁元素易于向铝侧扩散,扩散层主要位于靠近界面的铝侧;随着退火温度的升高,形成的扩散层逐渐变厚;退火前界面处物相组成为Mg基体、Al基体、Mg_(2)Al_(3)和Mg_(17)Al_(12),退火温度为300℃、350℃和400℃时,物相组成不变;当退火温度从300℃提高到400℃时,复合板的抗拉强度逐渐下降,而断面收缩率和断后伸长率逐渐升高;对拉伸断口的分析表明,复合板铝侧为韧性断裂,镁侧为脆性断裂;经300℃、350℃和400℃退火后,复合板界面结合区剪切强度分别为50.88 MPa、33.15 MPa及19.50 MPa,明显低于退火前的剪切强度(98.44 MPa);经300℃、350℃和400℃退火后,复合板硬度分别为158.1HV、146.3HV及152.6HV,明显高于退火前的硬度(129.6HV),且镁侧硬度变化较大。退火后界面结合区的高硬度是由于在扩散层中有硬脆相金属间化合物Mg_(2)Al_(3)和Mg_(17)Al_(12)生成。

The microstructure and properties of 5052/AZ31B explosive welded composite plates were studied after annealing at 300℃,350℃and 400℃.The results show that magnesium atom is easy to diffuse to the aluminum side during annealing,and the diffusion layer is mainly located at the aluminum side near the interface.With the annealing temperature rising,the diffusion layer becomes thicker.The phase composition at the interface before annealing was Mg matrix,Al matrix,Mg_(2)Al_(3)and Mg_(17)Al_(12),and they remained unchanged after annealing at 300℃,350℃and 400℃.When the annealing temperature rises from 300℃to 400℃,the tensile strength of the composite plate gradually decreases,while the reduction of area and the elongation after fracture increase.The morphology of the tensile fracture shows that the aluminum side of the composite plate presents ductile fracture while the magnesium side presents brittle fracture.The shear strength of the interface bonding zone of the composite plate is respective 50.88 MPa,33.15 MPa and 19.50 MPa after annealing at 300℃,350℃and 400℃,which is significantly lower than that before annealing(98.44 MPa).The hardness of the interface of the composite plate is respectively 158.1HV,146.3HV and 152.6HV after annealing at 300℃,350℃and 400℃,which is significantly higher than that before annealing(129.6HV),and the change of hardness at the magnesium side is great.The high hardness of the interface bonding zone after annealing is due to the formation of the hard and brittle intermetallic compounds Mg_(2)Al_(3)and Mg_(17)Al_(12)in the diffusion layer.