目的 通过有限元仿真，预测飞机用钛-钢搭接件腐蚀部位和腐蚀深度。方法 采用动电位极化，测得温度为40 ℃、pH=4.0的5%NaCl溶液中TC18钛合金、30CrMnSiNi2A高强度钢和30CrMnSiNi2A镀锌钢三种材料的极化曲线。以极化曲线及其拟合的电化学动力学参数作为边界条件，建立异种材料搭接件电偶腐蚀仿真模型。通过模型计算分别得到镀锌层完好和镀锌层完全破坏后的表面电位分布和局部电流密度分布，并与实验室腐蚀试验结果进行对比。结果 腐蚀前期，镀锌钢紧固件表面优先发生腐蚀，表面镀锌层腐蚀从点蚀开始，并慢慢扩大，逐渐由局部腐蚀发展成均匀腐蚀；直到第5周期镀锌层基本完全破损，紧固件30CrMnSiNi2A基材裸露，30CrMnSiNi2A由初始时的阴极极性转变为阳极极性，并与TC18钛合金形成新的电偶对，腐蚀在钢板表面迅速扩展。将第3周期和第7周期腐蚀试验后搭接区的腐蚀形貌分别与镀锌层完好和镀锌层完全破损的仿真电位分布结果进行对比，可以看出，腐蚀形貌与低电位区的几何形状基本类似。根据法拉第定律，结合电流密度分布，预测腐蚀区域腐蚀深度，并与第3周期和第7周期腐蚀试验结果进行对比分析，结果发现，模型预测的腐蚀深度与第3周期和第7周期腐蚀试验结果相吻合。结论 试验结果与仿真结果具有较好的一致性，从而证明了仿真模型的正确性。

The work aims to use finite element simulation to predict the corrosion site and corrosion rate of titanium-steel lap joints for aircraft. Polarization curves of TC18 titanium alloy, 30CrMnSiNi2A high strength steel and 30CrMnSiNi2A galvanized steel were measured by potentiodynamic polarization in 5%NaCl solution at 40 ℃ and with pH=4.0. The simulation model of galvanic corrosion for lap joints was established with the polarization curve and its fitted electrochemical kinetic parameters as boundary conditions. The surface potential and local current density distribution under perfect and completely damaged state of galvanized layer were obtained through the model calculation, and the simulation results were compared with the experimental results. The corrosion occurred on the surface of galvanized steel fasteners preferentially at the early stage. Corrosion of zinc layer started from pitting corrosion and expanded slowly, and gradually developed from local corrosion to uniform corrosion. After five cycles, the zinc layer was completely broken and 30CrMnSiNi2A of fastener was exposed and changed from the cathodic polarity to the anode polarity. 30CrMnSiNi2A and TC18 formed a new couple pair and corrosion expanded rapidly on the surface of the steel plate. The corrosion morphology of lap area after third cycle and seventh cycle corrosion test was compared with the results of simulated potential distribution of intact galvanized layer and completely damaged zinc coating. The corrosion morphology was basically similar to that of low potential region of potential distribution. According to Faraday‘s law and current density distribution, the corrosion depth of corroded area was predicted and compared with the result of corrosion test after third cycle and seventh cycle corrosion test, the predicted corrosion depth of simulation model is agreement with the result of corrosion test after third cycle and seventh cycle corrosion. The experimental results are consistent with the simulation results, thus proving the correctness of the simulation model.