Passive Layer Analytics
Passive layer analytics is the detection of chromium-iron oxides on passivated stainless steel surfaces using electrochemical or spectroscopic methods. It shows the protection against pitting corrosion.
Physico-chemical mechanism of action
Passive layer analysis examines chromium-iron oxides on stainless steel surfaces that have formed due to corrosion processes. These oxides form a thin layer that protects the material from further corrosion.
Metallurgical relevance & risks during welding
A missing or too thin passive layer can lead to increased pitting corrosion. This can result in cracks and loss of mechanical properties of the material. Therefore, it is important to analyze the passive layer before welding and stabilize it if necessary.
Workshop practice & instructions
Before welding the stainless steel workpiece, the surface should be treated with a corrosion-inhibiting agent. This can be done by passivation or chromating. The passive layer should then be checked using spectroscopic methods (e.g., Raman spectroscopy) to ensure it is stable and sufficiently thin. If protection is lacking, additional treatment should be carried out.