How to Test the Resistance of Metal Against Corrosion?

When subjected to severe environmental conditions, metals tend to corrode. However, every metal behaves differently in standard conditions. On one hand, due to strong nature metal is used widely for different applications. On the other hand, the corrosive property is a big set-back. Coating, plating, painting, etc. are some way outs of protection from surroundings. In some industries, it is very crucial to protect the metal parts like fasteners, springs, ball bearings, etc. as they are backbone behind the operation of products. E.g. In spring-loaded hinges, if spring fails to perform due to corrosion, the whole product fails.

What is the test procedure?

Testing can be done in two ways, accelerated weathering conditions, cyclic corrosion testing. Well, it is certainly not possible to simulate the environmental conditions in the lab without using any machine or device. Xenon test Chamber and Corrosion test chamber can be used for this.

Xenon test Chamber creates a cyclic pattern of different environmental conditions. The specimen that is to be tested is exposed to 5 environmental conditions, UV light, Rain, Condensation, Temperature (up to 60°C) and humidity. All these conditions run in a cyclic manner to see how far the specimen resist to it. This is a very harsh test in comparison to salt spray test. This test does not give any documented readings, results are analysed by visual inspection.

Corrosion Test Chamber is also called Salt spray chamber. In this test, the specimen is exposed to the salt laden humid environment at a certain temperature. NaCl solution is used to create the fog, in-built heaters raise the temperature of the chamber. The specimen is kept inside the insulated chamber for certain time period, mentioned by the international standard organisation. After the test cycle is over, a visual inspection of a specimen is done to check if it sustains in the fog or develops corrosion evidence. This is the most widely performed test to check the resistance of the metal.

Presto offers another testing instrument for checking its resistance against corrosion, Washometer. It’s a very simple machine to use. It has a rotator in between the chamber. The specimen is kept on the mesh rack and placed inside the chamber. The temperature is set to the intended range and chamber is filled with liquid. As you start the test, the rotator will start rotating creating a whirlpool. In this test, you are exactly washing the specimen at a certain temperature for certain period as per the testing standards. Any liquid which is non-inflammable and does not harm the body of the chamber can be used to perform the test.