Magnetic properties of austenite
Channel: bhadeshia123
Date: 09/11/2020

It is sometimes the case that when buying stainless steel cookers, the customer will take a magnet to check whether the steel is austenitic or ferritic; if it is not, than the cooker is said to be made of quality steel, even though both are stainless.

There is a misconception that austenite is "nonmagnetic". I will show this talk that austenite is a most peculiar phase, even in pure iron, where it can be ferromagnetic or antiferromagnetic below the Curie and Neel temperatures respectively. You might wonder how this is established in pure iron, or why austenite has such a large thermal expansion coefficient than ferrite or nickel, or why the addition of sufficient nickel causes the expansion coefficient to go to zero. I hope to explain these and other effects using both theory and experiments reported over half a century.