碳钢、低合金钢全浸没海洋环境下最大点蚀深度简化模型

腐蚀是导致老龄船舶结构失效的主要原因之一。结合基本点蚀原理,文章对碳钢、低合金钢海水全浸没点蚀的主要影响因素、具体点蚀进程做了简要解释与评述。基于Melchers点蚀深度模型及其相关实验数据,文中提出一种简化形式的新型点蚀最大深度模型,并采用该模型对三组我国船舶结构常用碳钢、低合金钢的青岛海域全浸没点蚀试验观测数据进行分析。通过对比验证,证明采用Weibull函数表示点蚀最大深度随时间变化关系是合适的。此外,依据青岛、厦门、榆林海域碳钢试验数据,文中还对海水环境因素,如:溶解氧浓度、平均温度、盐度、PH值等,以及钢材成分变化对新型最大点蚀深度模型各参数的影响进行了初步探讨,得出了相应的函数关系式及相关结论。

A Simplified Maximum Pit Depth Model of Mild and Low Alloy Steels in Marine Immersion Environments

For mild and low-alloy structural steels under marine immersion conditions, the main influencing factors and the specific process of pitting corrosion were summarized in this paper.Based on the corresponding pitting corrosion mechanics and Melchers' pitting corrosion model, a simplified maximum pit depth model is proposed, which will be more concisely to predict the statistical characteristics of maximum macro-pit depth.Then the new model is applied to the analysis of various corrosion gauge data from some long term field investigations in China.Comparing with other pitting corrosion models,it is more reasonable to describe the maximum pit-depth curve of mild and low-alloy steels in marine immersion conditions as a Weibull function of exposure periods. Furthermore, the potential influences of some seawater environmental factors on model parameters are discussed,including seawater temperature, dissolved oxygen, salinity, PH, etc. Since the variations in the composition contents of mild and low-alloy steels will also make a full impact on maximum pit depth,comparative analyses of the effect of steel composition contents on pit depth and the model parameters are also carried out.