微量元素Cr对船用耐蚀钢焊接接头组织和性能的影响

Effect of Trace Element Cr on Microstructures and Properties of Welded Joints of Marine Corrosion Resisting Steels

为了探讨货油舱下底板模拟腐蚀环境下微量元素Cr对耐蚀钢焊接接头组织、力学性能和腐蚀性能的影响,分别使用不含Cr的焊丝和含微量Cr的焊丝焊接耐蚀钢,对所得焊接接头进行研究.对比分析无Cr及含微量Cr的焊接接头的组织及性能.结果表明,Cr元素的微量添加在一定程度上抑制了先共析铁素体,并且细化了针状铁素体.焊缝中微量Cr的存在对接头的力学性能影响大,无论添加与否接头的抗拉强度均比母材抗拉强度要高,且冲击水平也未发生大的改变,硬度分布相似.焊缝中添加微量Cr元素并未明显改善它的耐腐蚀性,相反,使得焊缝金属自腐蚀电位下降、腐蚀速率增高.

To explore the effects of trace element Cr on microstructure,mechanical performances and corrosive nature of welded joints in the virtual environment in which the bottom plates of cargo oil tanks were taken as the prototype,different joints were researched by adding wires with Cr or without Cr. The corrosion rate of the joint was calculated by weight loss of the samples before and after corrosion.However,the micro and macro morphology of the corroded samples were described by scanning electron microscope（ SEM） and optical microscope（ OM）,and the element distribution was measured by EDS.In addition,the polarization curve was measured in the preset corrosion environment. The results indicate that the minor addition of Cr inhibits the eutectoid ferrite to some extent and refines the acicular ferrite.The mechanical performance of the joints is little affected by the addition of Cr,and the tensile strength of the base metal is lower than that of the joint,and the shock level was not changed greatly. However the impact level is the same and the hardness distribution is similar. No significant changes are observed in anti-corrosion nature by adding trace amounts of Cr,but the corrosion potential of the weld metal decreases,meanwhile,the corrosion rate increases.