Magnetic vs. Non-Magnetic Metals

Galvanized Steel

Galvanizing is the process of applying a protective zinc coating to steel in order to prevent rusting. Even though zinc is a nonmagnetic metal, the coating is so thin that the magnetic properties of the steel are not hindered. Since ferrous metals are prone to rust, galvanized steel is an excellent selection for projects that require magnetic properties in corrosive environments.

Hot-rolled Steel

Hot rolled steel has been roll-pressed at extreme temperatures, making the steel easier to form, and resulting in products that are easier to work with. After the process of hot rolling, the steel shrinks slightly as it cools, giving less control over the shape and resulting in scaled surfaces, slightly round edges, and small distortions. Because of this, hot-rolled steel is ideal for magnetic projects where precise shapes and tolerances are not as important as hardness and strength.

Carbon Steel Pipes

Cold-rolled Steel

Cold-rolled steel is hot-rolled steel that is further processed for more precise dimensions, closer tolerances, and a better surface finish. Cold-finished steel is distinctive by its aesthetic appearance, having well-defined corners, more uniformity, and a smooth surface. Because of this cold-rolled steel is best suited for magnetic projects that require accurate precision or where visual appeal is important. However, because cold rolled steel requires more processing than hot-rolled steel, it also comes with a larger price tag.

Ferritic & Martensitic Stainless Steel

Stainless steels are prized for their excellent corrosion resistance as a result of their high chromium concentration. There are various classifications of stainless, and not all of them have magnetic properties. Out of the various types, ferritic and martensitic stainless steels (the 400 series) possess magnetism due to their high iron concentration and atomic arrangement. Similar to galvanized steel, ferritic and martensitic stainless steels are best suited for projects that require magnetic properties in corrosive environments such as high-temperature, chemical, and outdoor use.

Iron

Iron, whether cast iron or wrought iron, is an alloy with very low carbon content. Its purity makes it more resistant to rusting than other ferrous metals. It is soft and ductile while still possessing tensile strength. Wrought iron is easily welded, can be reheated, and can be worked into various shapes – becoming stronger the more it is worked. Its malleability makes wrought iron a choice material for magnetic projects that require repeated fabrication and resistance to corrosive environments.

Although the above list may seem rather extensive, most common metals are non-magnetic.

Austenitic stainless steels, such as 304 and 316, contain a high amount of austenite which makes them mostly non-magnetic. However, the crystal structure of austenitic stainless steel can be altered through work-hardening or special heat treatment to form ferrite (found in ferritic stainless steels) in some locations making them partially magnetic.

Aluminum’s structure, similar to lithium and magnesium, makes it non-magnetic by nature. When under high enough magnetic fields most matter will exhibit some magnetic attraction. But under normal circumstances, aluminum isn’t visibly magnetic.

Lastly, Copper and its alloys aren’t magnetic but can interact with magnets to a certain extent due to their electrical conductivity.