淬火速率对Al-5Zn-3Mg-1Cu铝合金厚板剥落腐蚀的影响

Effect of Quenching Rate on Exfoliation Corrosion of Al-5Zn-3Mg-1Cu Aluminum Alloy Thick Plate

采用末端淬火和腐蚀浸泡方法研究了淬火速率对Al-5Zn-3Mg-1Cu铝合金厚板剥落腐蚀性能的影响,结合金相显微镜、透射电镜和扫描透射电镜微观组织表征对影响机理进行了分析和探讨.Al-5Zn-3Mg-1Cu铝合金的剥落腐蚀性能随淬火速率的减小(2 160℃/min→100℃/min)而下降,腐蚀等级由P级变为ED级,最大腐蚀深度从15μm增加至530μm.淬火速率减小导致晶界析出相数量增加,其中Zn,Mg元素含量上升,无沉淀析出带宽化,是剥落腐蚀性能下降的主要原因.

The effect of quenching rate on the exfoliation corrosion of Al-5Zn-3Mg-1Cu alununum alloy thick plate was investigated by means of end-quench technique, corrosion immersion test, optical microscopy, transmission electron microscopy and scanning and transmission electron microscopy. The resistance to the exfoliation corrosion of Al- 5Zn-3Mg-1Cu aluminum alloy thick plate decreases with the decrease of quenching rate （from 2 160 ℃/min to 100 ℃/min）, and exfoliation corrosion rate is from P to ED with the maximum corrosion depth increasing from 15μm to 530μm The decrease of quenching rate leads to a larger amount of second phase particles at grain boundaries, a higher concentration of Zn and Mg in them and wider precipitate free zone near grain boundaries, which was the main reasons for lower resistance to exfoliation corrosion.