SAE Type 630 stainless steel (more commonly known as 17-4 PH, or simply 17-4; also known as UNS S17400) is a grade of martensitic precipitation hardened stainless steel. It contains approximately 15–17.5% chromium and 3–5% nickel, as well as 3–5% copper.[1] The name comes from the chemical makeup which is approximately 17% chromium and 4% nickel. SUS630 is the same as 17-4PH, and they both refer to the same grade. [2]

Properties

17-4 can be heat treated to high levels of strength and hardness, and features corrosion resistance[1] and machinability[3] 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.[1]

Overaging (aging beyond the peak strength condition) improves resistance to stress corrosion cracking.[4]

Applications

Uses for 17-4 stainless steel include components which require high hardness and corrosion resistance at temperatures of up to 600 °F (300 °C).[3] Specific applications for 17-4 include parts for aerospace, petroleum, chemical, and firearm industries.[1]

Composition

Proportion by mass (%)[1][3]
C Mn P S Si Cr Ni Cu Nb, Ta
0.07 max. 1.0 max. 0.04 max. 0.03 max. 1.0 max. 15.0–17.5 3.0–5.0 3.0–5.0 0.15–0.45

References

  1. ^ a b c d e "Type 630; 17 Cr-4 Ni; UNS 17400" (PDF). Outokumpu.com. Archived from the original (PDF) on December 23, 2015. Retrieved June 5, 2016.
  2. ^ "SUS 630(17-4PH)" (PDF). Atlas Steels. Retrieved April 23, 2021.
  3. ^ a b c "North American Stainless – Long Products Stainless Steel Grade Sheet" (PDF). North American Stainless. Retrieved June 5, 2016.
  4. ^ "Stress Corrosion Properties of High-Strength Precipitation Hardening Stainless Steels in 3.5% Aqueous Sodium Chloride Solution" (PDF). Archived from the original (PDF) on September 6, 2015. Retrieved September 6, 2016.

External links

SAE International
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