E690钢在青岛海域不同区带的初期腐蚀行为

Initial Corrosion Behaviour of E690 Steel in Different Seawater Corrosion Zones in Qingdao Sea Area

在青岛海域四个区带(大气区、飞溅区、潮差区、全浸区)对E690钢进行6个月的室外暴露试验,通过腐蚀速率测试、表面及截面形貌观察、腐蚀产物成分分析等,研究了该钢在不同区带的腐蚀行为。结果表明:经6个月暴露试验后,在潮差区该钢的腐蚀质量损失率和腐蚀速率最高,在大气区最低;该钢在四种区带环境中的腐蚀产物主要由α-FeOOH、γ-FeOOH和Fe_(3)O_(4)组成,不同区带对腐蚀产物的形成有显著影响,飞溅区氧气充足有利于Fe_(3)O_(4)形成,潮差区海水的周期性浸没使得电解液层持续存在,促进γ-FeOOH的形成;各区带试样均存在局部腐蚀,大气区及全浸区该钢表面的点蚀坑尺寸小、分布密集,而潮差区该钢表面的点蚀坑相互连结,尺寸及深度显著大于其他区带。

6-month outdror exposure experiment was carried out on E690 steel in four zones(atmospheric zone,splash zone,tidal differential zone and total immersion zone)in Qingdao seawater environment.The corrosion behaviour of E690 steel was studied by corrosion rate test,surface and cross-sectional morphology observation and corrosion product composition analysis.The results show that the corrosion mass loss rate and corrosion rate of the steel were the highest in the tidal differential zone and the lowest in the atmospheric zone after 6 months exposure test.The corrosion products of the steel in the four zones were mainly composed ofα-FeOOH,γ-FeOOH and Fe_(3)O_(4).The difference in zones had a significant effect on the formation of corrosion products.The sufficient presence of oxygen in the splash zone was conducive to the formation of Fe_(3)O_(4),and the periodic submergence of seawater in the tidal zone made the electrolyte layer persistent and promoted the formation ofγ-FeOOH.Localized corrosion existed in all zones.The corrosion pits on the surface of the steel in the atmospheric zone and the full immersion zone were small and densely distributed,while the corrosion pits on the surface of the steel in the tidal zone were connected to each other,and the size and depth were significantly larger than those in other zones.