Influence of Ultrasonic Rolling on Corrosion Resistance of 7075 Aluminum AlloyEI北大核心CSCD

表面纳米化处理是一种有效改善耐腐蚀性能的手段，但受表面粗糙度和残余应力等因素的影响，其相关机制并不清晰。 运用透射电镜(TEM)和扫描电镜(SEM)研究经超声表面滚压工艺(USRP)处理后 7075 铝合金的组织和性能。结果表明： 经 1 道次和 15 道次 USRP 处理后，7075 铝合金表面粗糙度减小并且引入了残余压应力。滚压 15 个道次的试样表面能获得平均晶粒尺寸为 52 nm 的纳米晶。相较于未处理试样，经 1 道次和 15 道次 USRP 处理后试样的耐腐蚀性能均显著提高。其中， 滚压 15 个道次试样的耐腐蚀性能提升更为显著。这主要是因为纳米晶可以使材料表面形成更加致密的钝化膜，导致其耐腐蚀性能显著提高，而表面粗糙度降低和引入残余压应力是提升耐腐蚀性能的次要因素。对比分析残余应力、表面粗糙度和表面纳米晶对 7075 铝合金耐腐蚀性能的影响，揭示了 7075 铝合金经表面纳米化处理后耐腐蚀性能提升的机制。

Influence of Ultrasonic Rolling on Corrosion Resistance of 7075 Aluminum Alloy

Surface nanocrystallization is an effective means to improve corrosion resistance, but it is affected by factors such as surface roughness and residual stress, and the related mechanism is not clear. The microstructure and corrosion properties of 7075 aluminum alloy treated by ultrasonic surface rolling process (USRP) are investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that after 1 pass and 15 passes of USRP treatment, the surface roughness of 7075 aluminum alloy is reduced and residual compressive stress is introduced. After 15 passes of rolling, nanocrystals with an average grain size of 52 nm can be obtained on the surface of the sample. Compared with the untreated sample, the corrosion resistance of the sample after 1 pass and 15 passes of USRP treatment is significantly improved. Among them, the corrosion resistance of the 15-pass rolling sample has been improved more significantly. This is mainly because the presence of nanocrystals can form a denser passivation film on the surface of the material, leading to a significant improvement in its corrosion resistance. The reduction of surface roughness and the introduction of residual compressive stress are secondary factors to improve the corrosion resistance. This paper analyzes the effects of residual stress, surface roughness and surface nanocrystals on the corrosion resistance of 7075 aluminum alloy, and reveals the mechanism of the corrosion performance of 7075 aluminum alloy after surface nanocrystallization.