300 series stainless steels are classified as austenitic, and are hardenable only by cold working methods. Very popular, easy to machine and inexpensive we keep an inventory of domestic 300 series steels in several sizes. This material is used in industries from comercial to aerospace. Fast Lane has a lot of experience with 300 series stainless steel. We have made many different parts on all our machines, from the 5 axis mill down to our 12mm Swiss machine.