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
New South Wales stainless steel carriage stock New South Wales stainless steel carriage stock The New South Wales stainless steel carriage stock was a type of passenger carriage operated by the New South Wales Government Railways from 1961 until 1993. These carriages were mainly used on interstate trains such as the Southern Aurora, which ran between Sydney and Melbourne, its slower counterpart the Spirit of Progress and the Brisbane Limited. They were also used on the Gold Coast Motorail to Murwillumbah. With the demise of locomotive-hauled trains, the majority of the carriages passed to the Australian Railway Historical Society, Canberra and New South Wales Rail Transport Museum