X70高钢级管线钢焊接接头盐雾腐蚀机理

发布时间：2018-07-02 09:04

本文选题：X管线钢 + 焊接接头　；参考：《焊接学报》2015年05期

【摘要】：利用中性盐雾试验对X70高钢级管线钢焊接接头进行室温腐蚀,通过扫描电镜和能谱仪观察了X70管线钢焊接接头盐雾腐蚀前后表面微观形貌和化学元素的变化,并采用EDS对盐雾腐蚀后焊接接头表面进行了面扫描分析.利用XRD讨论了其盐雾腐蚀前后表面物相,分析了X70管线钢焊接接头盐雾腐蚀后表面腐蚀膜的组成、作用和腐蚀机理.结果表明,盐雾腐蚀后失效主要形式是点蚀和剥落腐蚀,活性Cl-离子破坏了试样表面的钝化膜,与Fe原子接触,是发生点蚀的主要原因;焊接过程中产生的残余拉应力成为腐蚀的应力源,使材料在腐蚀介质中发生应力腐蚀开裂,在与晶间腐蚀共同作用下发生剥落腐蚀;腐蚀膜达到一定厚度后覆盖在试样表面,阻隔试样与腐蚀介质的接触,有利于抑制腐蚀的持续进行.
[Abstract]:The welded joints of X70 high grade pipeline steel were corroded at room temperature by neutral salt spray test. The surface morphology and chemical elements of X70 pipeline steel welded joints before and after salt spray corrosion were observed by SEM and EDS. EDS was used to analyze the surface of welded joints after salt spray corrosion. The surface phase before and after salt spray corrosion of X70 pipeline steel was discussed by XRD, and the composition, effect and corrosion mechanism of the corrosion film after salt spray corrosion of welded joint of X70 pipeline steel were analyzed. The results show that the main failure forms after salt spray corrosion are pitting corrosion and exfoliation corrosion. Active Cl- ions destroy the passivation film on the surface of the sample and contact with Fe atoms, which is the main reason for the pitting corrosion. The residual tensile stress produced in the welding process becomes the stress source of corrosion, which causes the material to crack in the corrosive medium and exfoliate under the joint action of intergranular corrosion, and the corrosion film reaches a certain thickness and covers the surface of the sample. Blocking the contact between the sample and the corrosion medium is beneficial to the inhibition of the continuous corrosion.
【作者单位】：常州大学机械工程学院;常州大学江苏省材料表面科学与技术重点实验室;
【基金】：江苏省自然科学基金资助项目(BK2009104) 江苏省普通高校研究生科研创新计划资助项目(XM2011-388)
【分类号】：TG406;TG142.31

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