How to test the corrosion resistance of Metal parts?

The corrosion resistance performance of Metal parts directly determines their service life.The testing core is to simulate the actual usage environment and evaluate the corrosion resistance of the surface protective layer(such as galvanizing,anodizing)or substrate.The following is a 500 word core testing method and application instructions:

The mainstream detection method is based on salt spray testing,combined with targeted scenario testing.Neutral salt spray test(NSS)is the most commonly used standard method.The accessories are placed in an atomizing environment of 5%sodium chloride solution(temperature 35℃),and the corrosion condition is evaluated by continuous spray:ordinary galvanized parts need to be free of obvious corrosion for 96 hours,and hot-dip galvanized and Dacromet process accessories are required to be≥720 hours,which is suitable for outdoor general scenarios.Acid salt spray testing(CASS)simulates marine and acidic industrial environments,with a pH value of 3.1-3.3 and a temperature of 50℃.It has higher testing intensity and is commonly used in precision electronics and automotive parts.The qualification requirement is no pitting corrosion for≥48 hours.

For special scenarios,specialized testing is required:humidity and heat testing(temperature 40℃,humidity 90%)simulating rainforest and humid environment,continuous testing for 7-30 days,observing whether the accessories have mold spots or rust;Immersion testing involves immersing accessories in saltwater or acidic alkaline solutions(such as 3%sulfuric acid solution)to evaluate their performance under long-term exposure to corrosive media.It is suitable for plumbing fittings and chemical equipment accessories.

Electrochemical testing is the core means of precise evaluation,which quickly quantifies corrosion rate and protective layer impedance through methods such as polarization curves and electrochemical impedance spectroscopy(EIS).It is suitable for quality control of R&D stages or high-end accessories.In addition,outdoor exposure testing(placed in a natural environment for 6-12 months)can truly reflect the corrosion resistance of accessories under sunlight and rain,but the cycle is long and is often used for long-term performance verification of products.

The determination of test results should be based on industry standards(such as GB/T 10125,ASTM B117),with a focus on observing whether there is pitting,rust spots,or coating peeling on the surface of the accessories,and recording the time of the first occurrence of corrosion.In actual testing,corresponding methods should be selected based on the usage scenarios of accessories to ensure that the testing results are consistent with the actual usage effects,providing scientific basis for product selection and quality control.