Q690高强钢对接焊缝加速腐蚀试验研究

Corrosion Characteristics of Butt Welds of Q690 High Strength Steel in Laboratory Test as an Enviormental Simulation of Ocean Splash Zone

为研究Q690高强钢对接焊缝在海洋浪溅区的腐蚀特性,进行室内加速腐蚀实验,通过对不同周期下的表面宏观与微观腐蚀形貌的观察以及质量损失率、蚀坑尺寸和腐蚀速率等参数的测定,分析了试件损伤程度随腐蚀周期的变化规律。结果表明:随着腐蚀周期增加,金属光泽逐渐变暗,焊缝连接处分布较多锈蚀物,质地较为疏松,局部区域存在剥落现象;当腐蚀100 d后,试件质量损失率为8.46%。根据激光扫描共聚焦显微镜分析结果可知,表面堆积物能够抑制腐蚀沿深度方向延伸,腐蚀过程是由针状点蚀逐渐向坑蚀过渡,焊缝区、热影响区的蚀坑平均深度分别约为311.01和333.24μm。研究结果对于海洋环境下国产高强钢耐久性评估具有重要意义。

The corrosion characteristics of butt welds of Q690 high strength steel in the ocean splash zone was studied via laboratory simulation with a desired accelerated corrosion scheme of cyclic immersion in artificial seawater and maintenance in hot and humid chamber, in terms of the macroscopic and microscopic corrosion morphology, mass loss, pit size, and corrosion depth etc., so that to acquire the corrosion regulation of the steel. The results show that as the corrosion cycle increases, the metal luster gradually darkens, more rusts emerge on the weld joints, the formed rust rather loose with pelling off can be seen at local areas. After 100 d of corrosion, the mass loss rate of the steel is 8.46%. The observation results of laser scanning confocal microscope(LSCM) show that surface deposits can inhibit corrosion from extending along the depth direction. The corrosion process gradually transforms from needlelike corrosion spots to corrosion pits, the average depths of pits in the weld zone and heat affected zone are about 311.01 and 333.24 μm, respectively. The research results are of great significance for the durability evaluation of domestic high strength steel in marine environment.