Corrosion resistance testing of metal materials

Thread Content

The last edit to this post was made by yx5494 on 2021-4-29 at 14:06. The evaluation methods for testing metal corrosion resistance can be divided into three categories: gravimetric methods, visual surface inspection methods, and electrochemical testing methods. 1. Gravimetric method: The gravimetric method is the most fundamental, as well as the most effective and reliable quantitative evaluation method in the study of a material’s corrosion resistance. Although the gravimetric method has the drawback of being unable to study the corrosion mechanism of materials, it can characterize a material’s corrosion resistance in a relatively accurate and reliable manner by measuring the change in weight of the material before and after corrosion. For this very reason, it has been widely used in corrosion research, serving as the basis for the identification and comparison of many modern analytical and evaluation methods in electrochemistry, physics, and chemistry. The gravimetric method is divided into two types: the weight-increase method and the weight-decrease method. Both use the difference in weight of the sample before and after corrosion to determine the corrosion rate. In the former case, the sample is weighed along with all the corrosion products after the corrosion test, while in the latter case, the sample is weighed after all the corrosion products have been removed. 2. Surface observation method 2.1 Macroscopic observation involves a visual analysis of the material’s morphology before and after corrosion, as well as before and after the removal of corrosion products. Attention should also be paid to the shape and distribution of these corrosion products, as well as their thickness, color, density, and adhesion ； At the same time, attention should also be paid to changes in the corrosive medium, including the color of the solution, as well as the shape, color, type, and quantity of the corrosion products in the solution. Although this kind of observation is quite rough, any detailed study of clothing relies on this method. 2.2 Microscopic observation involves performing metallographic examinations or fracture analysis on the corroded specimens, or using scanning electron microscopes, transmission electron microscopes, electron probes, etc. to analyze the microstructural features and phase composition; this enables the study of fine corrosion characteristics and corrosion kinetics. 3. Electrochemical testing method: The electrochemical testing method is a modern approach that can be used to study material corrosion quickly and accurately. Since most material corrosion is of the electrochemical type, electrochemical testing methods are widely used in corrosion studies. Compared with the weight method and surface observation method, electrochemical testing can not only study the corrosion rate of materials but also delve deeper into the corrosion mechanisms of these materials. Testing standards: ASTM D6294/D6294M-2013 – Standard test method for corrosion resistance of ferrous metal fastener assemblies used in roofs and waterproof roofs; ASTM F482-2003 – Standard test method for evaluating the corrosion resistance of aircraft metals by complete immersion in maintenance chemicals; ASTM D6294-1998(2003) – Standard test method for corrosion resistance of ferrous metal fastener assemblies used in roofs and waterproof roofs; ASTM D6294/D6294M-1998(2009)e1 – Standard test method for corrosion resistance of ferrous metal fastener assemblies used in roofs and waterproof roofs; ASTM D6294-1998 – Standard test method for corrosion resistance of ferrous metal fastener assemblies used in roofs and waterproof roofs; KS D ISO 9226-2003 – Corrosion resistance of metals and alloys. Atmospheric corrosion. Determination of corrosion rates using standard specimens. The above content was compiled by me; please indicate the source when reproducing it