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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.
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Properties
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.
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Applications
Uses for 17-4 include components which require high hardness and/or corrosion resistance at temperatures of up to 600 °F (316 °C). Specific applications for 17-4 include the petroleum and chemical industries, as well as use in aircraft parts.
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Composition
Source of the article : Wikipedia
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