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 about 0.4%) are mostly used for cutting tools: Cutlery, Razor blade steel, Blender blades, etc. Replacing some of the Carbon in martensitic stainless steels by Nitrogen is a fairly recent development. The limited solubility of Nitrogen has been increased by the PESR process (Pressure Electroslag Refining) in which melting is carried out under a high nitrogen pressure. Up to 0.4% N contents have been achieved leading to higher hardness/strength and higher corrosion resistance. As the PESR is expensive, lower but significant N contents have been achieved using the standard AOD process. They are magnetic. They are not as corrosion resistant