Residual Magnetism
Residual magnetization is the persistence of a magnetic field in a metal after removing the external magnetizing source. This can lead to damage and reduction of mechanical properties.
Physico-Chemical Mechanism of Action
Residual magnetization occurs when metals like steel or nickel are magnetized in a magnetic field. The magnetic dipoles within the material align and remain aligned even after removing the external field.
Metallurgical Relevance & Welding Risks
Residual magnetization can cause damage such as cracks or distortion. It impairs mechanical properties and can make the material more susceptible to corrosion. In the workshop, it can particularly cause problems when processing steel sheets or in magnetic machines.
Workshop Practice & Instructions
To avoid residual magnetization, metals should be demagnetized before welding. This can be done with a special machine that generates a strong magnetic field and then gradually reduces it. When processing steel sheets, it is especially important to ensure they are fully demagnetized.