摘要
通过对2219-T87搅拌摩擦焊接头宏观形貌、金相组织观察以及显微硬度和力学性能的测试,探讨了2219-T87母材及接头的微观特征对力学性能的影响规律。结果表明:由于金属塑性流动状态及温度的不同,造成了前进边与后退边在微观组织特征方面存在较大的差异,并直接影响了其宏观性能,如硬度和强度;后退边在硬度和强度方面比前进边要差,接头强度性能最差的位置是后退边热影响区和热机影响区的交界处附近,形成接头的薄弱区。对母材和接头的SEM观察可知:母材断口存在大量宏观塑性变形特征,即为强韧性断口类型;而接头断口则由较浅的网状等轴韧窝及边缘处的剪切型韧窝构成。
The influence of microstructure on the mechanical properties of 2219-T87 aluminum alloy base metal and friction stir welded joints were investigated by observing the appearance and microstructure and testing the hardness and mechanical properties. It is found that since the state of plastic flow of metal and temperature are different, the microstructural characteristics have a great difference between the advancing side and retreating side, which directly affects their macroscopic properties such as hardness and strength; at the same time, the hardness and strength on the retreating side were worse than those on the advancing side, and the worst area of mechanical properties of the welded joint locates on the junction of thermomechanically affected zone and heat affected zone on the retreating side, forming the weakest areas of the joints. SEM observations show that the fracture surface of base metal is of a large number of macroscopic plastic deformation characteristics, which is the fracture toughness type; while the joint is of network shallow equiaxed dimples with some shear dimples.
基金
上海航天八院专项科研横向基金项目
关键词
铝合金
搅拌摩擦焊
微观组织
力学性能
aluminum alloys
friction stir welding （FSW）
microstructure
mechanical properties
