From time to time we receive calls stating stainless steel fasteners we supplied are magnetic and there must be something wrong with them since stainless is non-magnetic.
This is a myth and one of the bigger misconceptions in the fastener industry and we will explain in more detail to calm some of the confusion…
Some alloys, particularly 410 and 18-8 types, which include 302 and 304SS, may exhibit magnetic properties after being subjected to the severe stresses produced when cold forming (for example: forming the head during fastener manufacturing processes). This is especially true when cold forming smaller items such as screws. Cold forming occurs in the wire drawing, forming, and thread rolling process. Each of the processes will, typically, create enough martensite (a change from austenite) to produce a measurable degree of magnetism.
Without a complete annealing treatment of the post cold worked part, it will never have zero magnetism. We have additional professionally researched articles that will provide additional information should it be needed.