Method for evaluating galvanic corrosion under thin liquid film

Abstract

The invention discloses a method for evaluating galvanic corrosion under a thin liquid film. The method comprises the following steps: (1) preparing a lap joint sample; (2) preparing a control sample; (3) carrying out a salt spray test; (4) carrying out corrosion evaluation, namely measuring the average corrosion depths of the to-be-tested sample A, the to-be-tested sample B, the control sample A0 and the control sample B0, namely Ztst-A, Ztst-B, Zref-A and Zref-B, detecting and judging whether the Ztst-A is obviously different from the Zref-A and the Ztst-B is obviously different from the Zref-B according to statistics t, and if the Ztst-A is obviously different from the Zref-A and the Ztst-B is obviously different from the Zref-B, calculating respective galvanic effect values of the material A and the material B. According to the method, the description of the corrosion degree is quantified by using the corrosion depth data, the galvanic couple effect between different metals can be evaluated more accurately, and objective comparison is facilitated.

Description

technical field [0001] The invention relates to metal materials, in particular to an evaluation method for galvanic corrosion under a thin liquid film. Background technique [0002] With the tightening of energy saving and emission reduction requirements, the application proportion of lightweight materials in industrial products is increasing. The resulting galvanic corrosion between different materials has also attracted the attention of many engineers. Therefore, how to economically and effectively evaluate the level of galvanic effect between galvanic couple combinations in the atmospheric environment has become one of the concerns of the industry, especially the automotive industry. [0003] Chinese invention patent CN111141661A discloses a method for evaluating galvanic corrosion of a mechanically connected structure of dissimilar metal sheets in an automobile, comprising the following steps: (1) evaluating two kinds of sheet materials of the mechanically connected str...

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Problems solved by technology

[0004] The above-mentioned patents have the following defects: 1. The processing procedure of the sample to be corroded is complicated. First, the polarity of the two materials must be distinguished, and then an anodic plate with holes is made according to the polarity, and cathodic bolts and nuts are made, and then a connection test is formed. 2. The accuracy is poor, galvanic corrosion only occurs in a limited area, and the weight loss caused by galvanic corrosion before and after the test is very small, and the weight loss by corrosion is used for evaluation. The level of galvanic corrosion cannot be accurately evaluated; 3. The risk level of galvanic corrosion between mechanical structures can only be qualitatively obtained, and the degree of galvanic corrosion at the same risk level cannot be compared

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