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 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.
Proportion by mass (%)
- ^ "UNS S17400 Stainless Steel Precipitation Hardening Grade".
- ^ a b c d e "Type 630; 17 Cr-4 Ni; UNS 17400" (PDF). Outokumpu.com. Retrieved June 5, 2016.
- ^ a b c "North American Stainless - Long Products Stainless Steel Grade Sheet" (PDF). North American Stainless. Retrieved June 5, 2016.
- ^ "Stress Corrosion Properties of High-Strength Precipitation Hardening Stainless Steels in 3.5% Aqueous Sodium Chloride Solution" (PDF). Retrieved September 6, 2016.
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