Free Iron Test
The Free Iron Test is an analytical method for detecting unbound iron particles on passivated stainless steel surfaces. It serves quality control and helps avoid foreign corrosion.
Physicochemical Mechanism of Action
The Free Iron Test uses a chemical reaction between the stainless steel and a solvent that indicates unbound iron. This solvent reacts specifically with free iron ions, forming a visible product that signals the presence of unbound iron.
Metallurgical Relevance & Welding Risks
Unbound iron can cause corrosion because it acts as an electrolyte and creates a galvanic contact between the stainless steel and other metals or environmental substances. This can lead to cracks and wear of the components. The Free Iron Test helps ensure the stainless steel surface is protected against corrosion.
Workshop Practice & Instructions
To perform the Free Iron Test, you bring a stainless steel sample into contact with a special test agent. The reaction is visually observed and documented. A positive result shows the presence of unbound iron and indicates a compromised surface. In that case, corrosion protection measures should be taken, like passivating the steel or applying a corrosion-inhibiting lubricant.