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
Braided stainless steel brake lines tubing such as galvanized or stainless steel pipe, as this would prevent any expansion along the hydraulic fluid path, providing the most direct transfer of operator input force to the friction surfaces, and in fact most of the length of a brake line is made of stainless steel. However, hard tubing will not endure the motions caused by articulation of suspension components. For example, an automobile wheel is not hard-mounted to the automobile's frame or unibody chassis. It is instead mounted to a suspension component which allows that wheel to move in response to road irregularities and steering inputs. Because