2524铝合金是高抗损伤容限的新型航空高强铝合金。采用高功率光纤激光器焊接2 mm厚2524铝合金，研究了原始包铝表面、去除包铝层表面氧化膜和去包铝层时的焊接结晶裂纹倾向，借助光学显微镜和电子显微镜分析了焊缝组织形态。结果表明，去氧化膜时结晶裂纹倾向最大，去包铝层后结晶裂纹倾向最小。不同表面状态对结晶裂纹的影响与焊缝组织晶粒大小、共晶形态及其数量密切相关。2524铝合金表面包铝层的存在稀释了焊缝合金元素，共晶数量较少，对裂纹“愈合”作用减弱，因此结晶裂纹倾向大；而包铝层表面氧化膜在焊接时卷入焊接熔池，成为异质形核核心，焊缝组织细小、晶界共晶分布不连续，从而可降低结晶裂纹倾向。

Aluminum alloy (AA) 2524 is a new aircraft material with high damage tolerance and high strength. Bead-on-plate welding of AA2524 with a thickness of 2 mm using a high power fiber laser is presented. Solidification cracking susceptibility and microstructures of the joints for the original alclad-including surface (OS), oxide-film removed surface (OR) and alclad removed (AR) surface are investigated by optical microscopy (OM) and electron microscope. The results indicate that the OR and the AR joints have the maximum and minimum solidification cracking susceptibility, respectively. Different surface status joints have different grain sizes, morphologies and quantities of eutectic, leading to the different solidification cracking susceptibilities. The alclad on the surface of AA2524 can dilute the alloying elements in joints, reduce the quantity of eutectic and weaken the healing effect, thus increasing the solidification cracking susceptibility. The oxide-film on the surface of alclad can be involved in welding pool, act as heterogeneous nucleation site playing an important role in refining grain size, promote a discontinuous eutectic distribution and reduce the solidification cracking susceptibility.