2A12/5052异种铝合金激光焊接头的组织与性能

Microstructure and properties of laser welded joints of 2A12/5052 dissimilar aluminum alloy

利用光学显微镜、扫描电镜、X射线衍射仪和拉伸实验机、显微硬度计等研究了2A12/5052异种铝合金激光焊接接头的组织和性能。结果表明：当焊接功率为1800 W、焊接速度为0.02 m/s、离焦量为0时,焊缝成形最好,此时焊缝强度达到最大为200 MPa;焊缝处组织主要为α-Al和少量的S（CuMgAl_2）相;2A12侧热影响区组织为α-Al、θ相（CuAl_2）和S相（CuMgAl_2）,5052侧热影响区组织为α-Al;焊接接头硬度在2A12侧热影响区最高,其次是焊缝,硬度最低为5052侧热影响区。

Microstructure and properties of laser welded joints of 2 A12/5052 dissimilar aluminum alloys were investigated by means of optical microscope, scanning electron microscopy（SEM）, X-ray diffractometer（XRD）, tensile test machine and microhardness test. The results show that when the laser power is 1800 W, welding speed is 0.02 m/s and the defocusing is zero, the weld formation is the best, and the maximum strength of weld seam is 200 MPa. The microstructure of the weld seam consists of α-Al and a small amount of S（CuMgAl_2） phase. The microstructure of the heat-affected zone of near 2 A12 side is α-Al, θ phase（CuAl_2） and S phase（CuMgAl_2）, and the microstructure of the heat-affected zone of near 5052 side is α-Al. The hardness of welded joint is the highest in heat affected zone of 2 A12 side, followed by weld seam, and the lowest hardness is in heat affected zone of 5052 side.