Stainless steel as the common ferritic and austenitic stainless steels due to their low chromium content. Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim usually being to produce a 50/50 mix, although in commercial alloys the ratio may be 40/60. They are characterized by high chromium (19–32%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. Duplex stainless steels have roughly twice the strength compared to austenitic stainless steels. Their mixed microstructure provides improved resistance to chloride stress corrosion cracking in comparison to austenitic stainless steels Types 304 and 316. The properties of
Stainless steel are relatively poor conductors of electricity, with significantly lower electrical conductivity than copper. Ferritic and martensitic stainless steels are magnetic. Annealed austenitic stainless steels are non-magnetic. Work hardening can make austenitic stainless steels slightly magnetic. Galling, sometimes called cold welding, is a form of severe adhesive wear which can occur when two metal surfaces are in relative motion to each other and under heavy pressure. Austenitic stainless steel fasteners are particularly susceptible to thread galling, although it also occurs in other alloys that self-generate a protective oxide surface film, such as aluminum and titanium. Under high contact-force sliding this oxide