0Cr13Ni5Mo马氏体不锈钢在静置长江水中的腐蚀原因探讨

Corrosion Reason of 0Cr13Ni5Mo Martensitic Stainless Steel Under Static Fresh Water Condition in Yangtze River

由0Cr13Ni5Mo马氏体不锈钢与Q345碳钢复合的复合钢板焊接制作的某大型水利排砂钢管设施,在静止长江淡水条件下出现严重点蚀.通过距焊缝不同距离的不锈钢表面的腐蚀电位、点蚀击穿电位、重钝电位的电化学研究以及其金相组织和元素(Cr,C)含量变化等分析发现:焊接加工中的热效应导致马氏体不锈钢某些部位的表面Cr含量降低,晶粒与晶界处出现C的聚集,金相组织粗大,从而优先产生点蚀.讨论了不同焊接工艺热影响作用,焊接电流越大,热效应越明显.

The large water conservancy facilities, which have serious point corrosion under static fresh water condition in Yangtze River,is weld by the compound steel plate of the 0Cr13Ni5Mo martensitic stainless steel and the Q235 carbon steel. By the electrochemistry research of corrosion electric potential, point corrosion electric potential and other electric potential of the stainless steel surface with different distance from the welding line, as well as the analysis of content variety of its metallography organization and the element（Cr, C）,it can be seen that hot effect in the process of welding causes Cr content on the surface of some parts of martensitic stainless steel lower, C is accumulated between crystalloid boundary, and the metallography organization becomes bulky . Therefore it is preferential to produce point corrosion. Heat influence actions of different welding technologies are discussed, and the more big welding electric current is, the more obvious the heat effect.