17-4 stainless steel 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, 17-4 is magnetic. 17-4 is capable of being hardened up to approximately 44 Rc when heat treated to condition H900. Overaging (aging beyond the peak strength condition) improves resistance to stress corrosion cracking. Uses
Stainless steel on the surface. A final finish can then be applied to achieve the desired aesthetic appearance. Most of the world stainless steel production is produced by the following process Hot rolled coils are pickled in acid solutions to remove the oxide scale on the surface, then subsequently cold rolled (Sendzimir rolling mills), annealed in a protective atmosphere, until the desired thickness and surface finish is obtained. Further operations such as slitting, tube forming, etc. can be carried out in downstream facilities. Hot rolled bars are straightened, then machined to the required tolerance and finish. Wire rod coils are subsequently processed