Stainless steel duplex stainless steels are achieved with an overall lower alloy content than similar-performing super-austenitic grades, making their use cost-effective for many applications. Duplex grades are characterized into groups based on their alloy content and corrosion resistance. Precipitation hardening stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than the other martensitic grades. The most common, 17-4PH, uses about 17% chromium and 4% nickel. The designation "CRES" is used in various industries to refer to corrosion-resistant steel. Most mentions of CRES refer to stainless steel, although the correspondence is not absolute, because
Martensitic stainless steel announced two years later in a January 1915 newspaper article in "The New York Times". Brearly applied for a U.S. patent during 1915. This was later marketed under the ""Staybrite"" brand by Firth Vickers in England and was used for the new entrance canopy for the Savoy Hotel in 1929 in London. Martensitic stainless steel Martensitic stainless steel is a specific type of stainless steel alloy. Stainless steels may be classified by their crystalline structure into three main types: "austenitic", "ferritic" and "martensitic". Martensitic stainless steels can be high- or low-carbon steels built around the Type 410 composition of iron,