Corrosion Testing

What is corrosion?

Corrosion is a natural process of material degradation. 

Corrosion occurs when the materials of a given product are exposed to prolong adverse environmental conditions.

While generally harmless to humans, different adverse environmental condition (like presence of salt water in the air, changes in the atmosphere as well as changes in the temperature and humidity) can have negative effects on numerous materials, coatings and in turn lead to malfunctioning products and shorter product life spans.
Testing for corrosion, including rust or other type of material degradation, can significantly help to improve not only the performance of a given product, but also prolong its life span. Corrosion testing enables manufacturers to better understand how susceptible their products, materials and coatings are to real life changing environmental conditions such as humidity, temperature, presence of fresh water or salt water in the atmosphere, and much more. 

These valuable insights enable manufacturers to better engineer their final products by incorporating specific materials and coatings to help extend their products' performance.

What methods are used to test for corrosion?

There are different test methods and practices used for doing accelerated corrosion testing. The most popular one, also known as Salt Spray Test is ASTM B117. This test method was originally publish in 1939. Since then, the ASTM B117 become as very popular and  widely known corrosion testing protocol. 

Although the ASTM B117 is very popular, it often shows a poor correlation with actual life exposure. Nowadays there are more advanced corrosion accelerated testing practices such as ASTM G85 also known as a Standard Practice for Modified Salt Spray (Fog) Testing. 

Most modern salt spray testers can not only test to the ASTM B117 protocol, but also test to the more sophisticated ASTM G85. Contrary to the ASTM B117 protocol, which continuously exposes testing samples to a constant salt fog, the ASTM G85 test will alternate between a diluted salt fog at ambient temperature and a drying cycle at higher temperature. 

The ASTM B117 is still the most popular corrosion test protocol. As mentioned previously, the test was originally published in 1939. Since then, there has been a lot of historical testing data gathered around that test.  In additional, many people are not even aware that the  ASTM G85 corrosion test exists.

There exist numerous other tests related to corrosion testing and cyclic corrosion testing such as the SAE J1959 that tests for corrosion prevention in automobiles underbodies.

Who carries out the corrosion tests?

Corrosion testing is usually carried out either internally or externally.

Internally

Some corporations prefer to have their own internal material testing department. The material testing staff can work directly with the R&D, Manufacturing and Quality Control departments. This can speed up the internal material testing processes, but this option is also subject to potential data manipulation and subjective reporting. 

Externally

On the other hand, some companies and product manufacturers prefer to deal directly with third party material testing laboratories. This helps firms avoid expensive in-house laboratory set-up fees. In addition, an external lab provides an independent third party quality verification, objective performance review and recommendations.


What conditions can be tested for corrosion?

Corrosion testing can be very versatile. Numerous real world environmental conditions can be replicated and tested.

Some of the popular conditions include:
  • Presence of salt or fresh water in the atmosphere. As well as alternating between the two.
  • Presence of high humidity in the air or alternating between mild humidity to very high humidity.
  • Changing temperatures
  • Galvanic corrosion that happens when different types of metals are connected together and exposed to common environments. 

What products can be tested for corrosion?

Anything that has metal or polymer components  and is designed to typically operate outdoors can be tested for corrosion or material degradation.
  • Transportation including Shipping Containers, Motocycles, Trucks, Cars, ATVs, Skidoos, Snowmobiles, aircraft parts, etc
  • Electronics including servers, circuits, screens, phones, tablets, etc.
  • Wind turbines, solar panels, metal parts for bridges, ships, planes, etc,
  • Military equipment including gear, weapons, airborne and naval equipment, etc
  • Consumer goods such as outdoor speakers, microphones, etc. 
Technically, any physical non perishable goods can be tested for corrosion and material degradation.

Who manufactures corrosion testing equipment?

Here are the leading corrosion testing equipment manufacturers:
  • Q-Lab is a manufacturer or corrosion testing equipment. Q-Lab is headquarter in Westlake, Ohio, USA and has a worldwide distribution network. Q-Lab has been operating since 1956.
  • Presto Testing Instruments is a manufacturer or different testing equipment including salt spray testing chambers. Presto is based in Faridabad, Haryana, India and distributes their equipment across the globe.

How long do corrosion tests take?

Depending on the product's materials and coating material degradation can happen very quickly or gradually over long period of time. 

The testing duration can also be influenced by the end use of the product. For example, a decorative product for a bathroom it can be tested for 96 hours. However, a power utility product can be tested during  2,000 hours. 

Periodic product inspections should also be done to get a better understanding of the product’s behaviour. 

The test duration in a lab depends on the expected product life expectancy in the real world. The longer the product is expected to last and perform, the longer the product needs to be tested in a material testing lab.