DP590双相高强钢焊缝在模拟酸雨溶液中的腐蚀行为

Corrosion Behavior of DP590 Dual-phase High-strength Steel Welding Seam in Simulated Acid Rain Solution

研究了DP590双相高强钢CO_2气体保护焊焊缝的组织与腐蚀性能。采用金相显微镜观察了焊缝和母材的微观组织,并用电化学测试、失重试验、腐蚀形貌观察方法研究了高强钢焊缝在不同p H值模拟酸雨中的腐蚀行为。结果表明,母材组织主要为等轴铁素体和珠光体组成,组织较均匀;焊缝组织主要是板条状贝氏体、铁素体和残余奥氏体。随着p H值的降低,焊缝和母材的自腐蚀电位均负移,自腐蚀电流密度增大,腐蚀速率加快,且同一p H值下焊缝的耐蚀性差于母材。焊缝较母材的耐蚀性差主要是由于受到明显的电偶腐蚀。

The microstructure and corrosion resistance of CO,. gas shielded arc welding seam of DP590 dual-phase high-strength steel were studied. The microstructure of welding seam and base metal was observed by metallographic microscope, and the corrosion behavior of high-strength steel welding seam in simulated acid rain solution with different pH values was studied by the electrochemical test, weight loss test and corrosion morphology observation. The results show that the microstructure of base metal consists of equiaxed ferrite and pearlite, and the mierostructure is homogeneous. The microstructure of welding seam is mainly lathy bainite, ferrite and retained austenite. With the decrease of pH value, the corrosion potential of welding seam and base metal shifts in negative direction, the corrosion current densities increase, and the corrosion rates increase. Under the same pH value, the corrosion resistance of welding seam is worse than that of base metal. The reason that the corrosion resistance of welding seam is worse than that of base metal is mainly due to obvious galvanic corrosion.