The difference between 304 and 440 stainless steel bearings

Stainless steel bearings have three type of materials: 440, 304, and 316. The 440 &304 are common stainless steel bearings.

The 440 material is definitely magnetic, which means that it can be sucked. 304 and 316 belong to micro-magnetism (many people say that it is incorrect that it is not magnetic), that is, it cannot be sucked by a magnet, but you can feel a little suction. Generally stainless steel bearing  are made of 304 material.

304 stainless steels is widely used too. Compared with 440, its price will be lower in terms of anti-corrosion ability and mechanical properties. The comprehensive performance is more comprehensive, so it is widely used. The disadvantage is that no further heat treatment can be performed to change its properties.

440 is a high-strength cutting tool steel (endnotes A, B, C, F, etc.), which can obtain higher yield strength after appropriate heat treatment, and belongs to the class of hard stainless steel. A common application example is "shaving blades.