Critical pitting temperature
The critical pitting temperature is the point above which pitting corrosion occurs on a metal surface under certain conditions. It indicates the corrosion resistance of materials.
Physical-Chemical Mechanism of Action
The critical pitting temperature (CPT) is the minimum temperature at which pitting corrosion can occur on a metal surface under defined test conditions (e.g., humidity and pH). This process is triggered by chemical reactions between the metal and the environment, leading to corrosion products.
Metallurgical Relevance & Welding Risks
A CPT that is too low means the material can corrode quickly under normal shop conditions. This can lead to cracks, deformation, and reduced component life. In welding, it's especially important to consider the CPT to ensure a stable weld.
Shop Practice & Action Guidelines
To determine the critical pitting temperature, metallurgists run specific tests. In the shop, select materials and welding processes so that the CPT exceeds expected operating conditions. This can be achieved by choosing proper protective measures, adequate cooling, and using corrosion-resistant materials.