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,
Sharon Steel Corporation the Sharon Steel Hoop Corporation in 1933. Aided by improvement in business conditions, the Sharon Steel continued to expand its sales volume and to make further improvements in production facilities during the thirties. Equipment for the production of terne and tin coating was added, a new product under the trade name of “Galvanite” was produced, and other specialties were added to the company's line of products. New electric furnaces were installed at the Lowellville Works to make stainless steel ingots to be converted into stainless steel strip on the Sharon finishing mills. A great change came about in the company