30CrMnSiA镀镉层厚度优化研究

目的基于GJB 594A《金属镀覆层和化学覆盖层选择原则与厚度系列》,综合考虑防腐蚀和疲劳性能,对30CrMnSiA镀镉层厚度进行优化。方法开展30CrMnSiA镀镉5个厚度系列的疲劳试验,计算材料的DFRcutoff,研究镀层厚度对疲劳性能的影响。通过中性盐雾试验,研究镀层厚度对材料抗腐蚀性能的影响规律,最后综合考虑疲劳及抗腐蚀性能,提出优化后的镀镉层厚度范围。结果镀层厚度控制在5~25μm时,材料的DFRcutoff下降幅度在15%以内,厚度超过25μm后基体材料的DFR_(cutoff)值下降20%。在中性盐雾环境下,厚度控制在12~25μm时,能满足海军飞机一般钢结构件抗腐蚀性能的要求,当厚度超过25μm后,继续增加镀层厚度对抗腐蚀性能的提升并不明显。结论镀镉使材料的疲劳性能降低,其抗中性盐雾腐蚀能力与镀层厚度成正比。针对海军飞机使用环境特点,推荐30CrMnSiA钢结构件的镀镉厚度范围为12~18μm,取上限值。

Thickness Optimization Study on 30CrMnSiACadmium Plated Layer

Objective To optimize the thickness of the 30CrMnSiA cadmium plating by comprehensive consideration of the corrosion resistance and fatigue properties based on the Selection principle and thickness series for metallic and chemical coatings of GJB594A.Methods Influences of the thickness of cadmium plating on the fatigue property and the corrosion resistance were studied by five thickness series fatigue tests to calculate the DFRcutoff value and neutral salt spray test of 30CrMnSiA steel. Finally, the plated thickness after optimization was put forward by comprehensive con-sideration of the corrosion resistance and fatigue property.Result The fatigue property declined by 15% when the plating thickness was controlled in 5 ~ 25μm, and declined by 20% when the thickness was more than 25μm. In neutral salt fog environment, the plating thickness controlled in 12 ~ 25μm could meet the design requirement for general steel structure corrosion protection. If the thickness exceeds 25μm, increasing the plating thickness its influences on the improvement of corrosion resistance was not obvious.Conclusion Cadmium plating decreases the fatigue property of materials. The cor-rosion resistance was proportional to the plating thickness in the neutral salt-frog environment. According to the envi-ronment characteristics of naval aircraft, it is recommended to adopt the upper limit value of 12 ~18μm for thickness of the 30CrMnSiA steel cadmium plating.