压力管道金属材料焊接接头的流动加速腐蚀性能

通过温度、压力、流速可控的流动加速腐蚀实验机,模拟某冷凝水管线工况,对20钢分别与20钢、Q345R钢和304不锈钢焊接接头的流动加速腐蚀性能进行研究。通过扫描电镜(SEM)和能谱仪(EDS)对腐蚀产物进行表征。结果表明:腐蚀速率从大到小依次为20钢-20钢、20钢-Q345R钢、20钢-304不锈钢;相对于20钢母材,3种焊接接头的腐蚀电流均变小,腐蚀电位均向正方向偏移,构成电偶腐蚀时加速了母材的腐蚀速度。在介质流动的状态下,20钢-20钢焊接接头腐蚀产物膜为柱状,20钢-Q345R钢焊接接头腐蚀产物膜为分层片状结构,20钢-304不锈钢焊接接头腐蚀产物为网状结构,其覆盖率从大到小依次为20钢-Q345R,20钢-304不锈钢,20钢-20钢。

Characterization of flow-accelerated-corrosion of pressure piping welded joints

The flow-accelerated-corrosion properties of the welded joints of 20 steel-20steel,20 steel-Q345R steel,and 20 steel-304 stainless steel under an operation condition of condensate pipeline were tested by flow-accelerated-corrosion test apparatus by the controllable temperature,pressure and velocity.The corrosion products were charaterized by scanning electron microscope(SEM) and energy disperse spectroscopy(EDS).Results showed that the corrosion rate of welded joints of 20 steel-20 steel was the maximum,and that of 20 steel-304 stainless steel was the minimum.Compared with the parent metal,the corrosion current of the three welded joints became smaller,and the corrosion potential shifted to the postive direction,thus the galvanic corrosion systems were constituted and the corrosion rate of the parent metal of 20 steel accelerated.Under the conditions of media flowing,the structure of corrosion product film of the welded joints of 20 steel-20 steel,20 steel-345R steel,20 steel-304 stainless steel presented columnar,interdigited and reticulatied one,respectively.The coverage rate of corrosion product films decreased in following order: 20 steel-Q345R steel,20 steel-304 stainless steel,20 steel-20 steel.