Grade 416 steel is a free-machining stainless steel with a machinability of 85%, highest of all stainless steels. With most of the free-machining stainless steels, the machinability can be improved by adding sulphur, which leads to the formation of manganese sulphide inclusions. Addition of sulphur also reduces the formability, weldability and corrosion resistance of 416 steels to below that of grade 410. Because of their high machinability and low cost, grade 416 steels are available in highly tempered, hardened or unhardened forms.