热带海洋环境下海水中微生物对45钢腐蚀行为的单因素影响

通过在热带海洋环境下对比45钢在自然海水和无菌海水中的腐蚀行为, 研究了微生物单因素对碳钢腐蚀行为的影响. 实验结果表明, 微生物对45钢平均腐蚀速率的影响与微生物种类和含量密切相关. 锈层中的微生物主要由假单胞菌、弧菌、铁细菌、硫杆菌、硫酸盐还原菌组成. 其中好氧菌、兼性厌氧菌、厌氧菌的含量均随浸泡时间呈规律性变化, 这也导致在不同浸泡时间下, 微生物的作用及作用机理的不同.

THE SINGLE EFFECT OF MICROBE ON THE CORROSION BEHAVIORS OF 45 STEEL IN SEAWATER OF TROPICAL OCEAN ENVIRONMENT

Biological elements have significant impact on lifetime prediction of marine carbon steel facilities. Microbe can produce pitting, crevice corrosion, selective dealloying and stress-oriented hydrogen-induce cracking, which accelerates both localized and average corrosion rates of carbon steel. The formation of microbe films can also reduce the steel corrosion rate through inhibition of oxygen diffusion and depletion of oxygen in the electrolyte and metal/solution interface. A comparing study of the corrosion behaviors of 45 steel in natural seawater and in sterile seawater in tropic condition shows that in most of immerging periods, the bacterial activity at the interface accelerates the average corrosion rate of the steel. However, when the corrosion time is 28 d, the biofilms inhibit the corrosion of 45 steel. The species and contents of microbe significantly influence the corrosion behavior of the steel. The microbe in the corrosion product mainly consists of Pseudomonas, Vibrio, Crenothrixandleptothrix, Thiobacillus, and Sulfate-reducing bacteria. The content of aerobe does not change with increasing the immerging time, but the content of anaerobe increases with increasing immerging time. The regular change of the content of microbe with the immerging time leads to the different microbe corrosion mechanisms for 45 steel.