E550钢埋弧焊接接头在模拟海洋大气环境中的腐蚀行为

采用增重测量、锈层截面观察、物相定量分析和电化学实验等方法研究了低合金耐候钢E550埋弧焊焊接接头在室内干湿循环加速腐蚀中的行为。结果表明:E550钢焊接接头的腐蚀速率低于母材。E550母材与焊缝的成分差异导致焊接接头不同部位的电位不同,并引起电偶腐蚀。电偶腐蚀对常规的大气腐蚀产生了抑制作用,造成焊接接头腐蚀前沿平整,锈层缺陷减少。随着表面锈层的生长,焊接接头表面不同部位的电位发生不同程度变化,并造成反复发生极性逆转,使腐蚀变得均匀,减弱了电偶腐蚀的局部腐蚀特征。

Corrosion behavior of submerged arc welded joint of E550 steel in simulated marine atmospheric environment

The atmospheric corrosion behavior of submerged arc welded joint of low alloy weathering steel E550 during accelerated corrosion in laboratory dry and wet cycle was studied by mass gain measurement,rust cross section observation,phase quantitative analysis and electrochemical experiment.The results show that the corrosion rate of the welded joint of the E550 steel is lower than that of the base metal.The difference of composition between E550 base metal and weld metal leads to the difference of potential in different parts of welded joint and leads to galvanic corrosion.The galvanic corrosion can inhibit the conventional atmospheric corrosion,resulting in the smooth of corrosion fronts of the welded joint and the reduction of rust layer defects.With the growth of surface rust layer,the potential of different parts of the welded joint changes in varying degrees,and leads to repeated polarity reversal,which makes the corrosion uniform and weakens the local corrosion characteristics of galvanic corrosion.