X70管线钢热浸渗铝处理后盐雾腐蚀行为

利用热浸渗技术对X70管线钢表面进行了渗铝处理，通过SEM和EDS观察了X70管线钢渗铝处理前后表面微观形貌和化学元素的变化，采用XRD分析了其盐雾腐蚀前后表面物相，研究了渗铝处理对X70管线钢盐雾腐蚀的影响。试验结果表明，盐雾腐蚀后未处理试样表面点蚀较为严重，热浸渗铝处理后试样表层形成一层致密的Al2O3层，有效地阻止了腐蚀性介质Cl-离子和基体活性铁的接触；热浸渗铝后X70管线钢渗铝层组织有多种析出物，其表层黑色物质为FeAl，有效地抑制了表面点蚀的发生；未处理试样表面含铁量高，产生活性铁原子，是盐雾腐蚀发生点蚀主要因素。

Salt spray corrosion behaviours of X70 pipe line steel by hot-dipped-aluminum treatment

The surface of X70 pipeline steel was processed with the technique of hot-dipped aluminum, the morphologies and the change of chemical elements of X70 pipeline steel before and after hot-dipped aluminum were observed with SEM (Scanning Electron Microscope) and EDS (Energy Dispersive Spectrdmeter), respectively, its phase before and after the salt spray corrosion were analyzed with XRD (X-Ray Diffractomer), the effect of hot-dipped aluminum treatment on salt spray corrpsion of X70 pipeline steel were researched. The results show that pitting corrosion of the primitive sample is relatively serious after the salt spray corrosion, a dense Al2O3 layer is formed on the sample by hot-dipped aluminum, which availably prevents the contact between the corrosive medium Cl- ion and active Fe of the substrate; there are a number of educts in the dipped aluminum layer of X70 pipeline steel after hot-dipped aluminum treatment, the dust-colour material on its surface is FeAl, that effectively restrains the occurring of surface corrosive pitting; the content of Fe in the sample in primitive state is higher, produce the active irons, that is the main factor of corrosive pitting.