17-4 stainless steel for 17-4 include components which require high hardness and/or corrosion resistance at temperatures of up to . Specific applications for 17-4 include the petroleum and chemical industries, as well as use in aircraft parts. 17-4 stainless steel SAE type 630 stainless steel (more commonly known as 17-4; also known as UNS 17400) is a grade of martensitic precipitation-hardened stainless steel. It contains approximately 15–17.5% (17) chromium and 3–5% (4) nickel, as well as 3–5% copper. 17-4 can be heat treated to high levels of strength and hardness, and features corrosion resistance and machinability comparable to austenitic 304 stainless. Being martensitic,
Stainless steel both the Petronas Twin Towers and the Jin Mao Building, two of the world's tallest skyscrapers. The Parliament House of Australia in Canberra has a stainless steel flagpole weighing over . The aeration building in the Edmonton Composting Facility, the size of 14 hockey rinks, is the largest stainless steel building in North America. La Geode in Paris is a nearly spherical building. The dome is composed of 6433 polished stainless steel equilateral triangles that form the sphere that reflects the sky. Stainless steel is quite frequently used for pedestrian and for road bridges. Product forms are tubes (Helix bridge),