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AISI 630 – SS 630

SS 630, contains approximately 17.5% chromium, 5% copper, and additional nickel, molybdenum, and other elements.
The maximum carbon content is 0.07%. It is analytically the same with the materials 17-4 ph.

AISI 630 is a martensitic, hardenable, stainless steel with high wear resistance, good corrosion resistance and high yield strength.

The combination of excellent mechanical properties and high corrosion resistance allows AISI 630 to be used in maritime environments, although it is susceptible to stress corrosion cracking in stagnant seawater. Notched impact strength is excellent at sub-zero temperatures.

SS630 is machinable both in the solution-annealed and hardened condition, whereby the machinability depends on the hardness. SS 630 is used in the aerospace, chemical, petrochemical and petroleum industries, in medical and dental technology, in plant construction and in shipbuilding. 630 ss for oil and gas industry.

International identifiers

ASTM A564-89 17-4PH, JIS SCS24 / SUS630, AFNOR Z7CNU15-05 / Z7CNU17-04, 1.4542, 1.4548

Chemical composition

AISI 630 C Si Mn P S Cr Mo Ni Cu Nb
min. bis bis bis bis bis 15 bis 3 3.0 5xC
max. 0.07 0.7 1.0 0.04 0.03 17.5 0.6 5 5.0 0.45


This steel alloy exhibits special properties such as suitability for low temperatures and operation up to approximately 315 °C. Notable for its high strength, toughness, and age-hardenable capability, the steel allows strength enhancement through cold forming with subsequent aging.


Forging of AISI 630 stainless steel occurs in a temperature range from 1180°C to 950°C, with cooling to room temperature taking place in the surrounding air.


Optimal welding conditions are essential, considering the stable presence of copper. To prevent stress cracking, the material must undergo solution annealing shortly after welding, followed by aging.

Corrosion resistance

SS 630 is suitable for use in marine environments, showcasing excellent mechanical properties and corrosion resistance. However, additional protection is needed against crevice corrosion caused by standing seawater.


AISI 630 is machinable in both the age-hardened and solution-annealed conditions, with machinability varying depending on the hardness state.

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Popular steel:
ss 440b, ss 17-4ph