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 it is reasonable to ask why rubber brake hose is used at all, instead of always using braided stainless steel hose. The most typical reason is cost, but also use case. Braided stainless steel hose is typically more expensive than rubber. When the cost difference is extrapolated across hundreds or thousands of units, it is quite compelling to opt for the rubber option, especially when the use case exhibits that the operator will not need or want the additional capabilities offered by a brake system equipped with braided stainless steel brake lines. It thus stands to reason that braided stainless