Dynamic Passive Layer
The breathing passive layer is a stabilized layer on the metal that absorbs oxygen and can repair itself automatically. This prevents permanent corrosion.
Physicochemical Mechanism of Action
The breathing passive layer forms on the metal surface through a chemical reaction with oxygen. It consists of a protective film that stores oxygen and reduces direct contact between the metal and the environment.
Metallurgical Relevance & Risks in Welding
The breathing passive layer is especially important in corrosion-prone steel. When damaged by mechanical forces or chemical influences, the layer repairs itself by absorbing oxygen again and stabilizing. This prevents permanent corrosion of the metal.
Workshop Practice & Instructions for Use
To maintain and protect the breathing passive layer, the following measures should be taken:
• When welding steel, use a clean weld without pores or cracks.
• Keep the cooling time after welding short and controlled to preserve the passive layer.
• Use suitable protective agents like silicon or chromium compounds to promote oxygen absorption.