17-4 Precipitation Hardening also known as Type 630 is a chromium-copper precipitation hardening stainless steel used for applications requiring high strength and a moderate level of corrosion resistance. High strength is maintained to approximately 600 degrees Fahrenheit (316 degrees Celsius).
Alloy 17-4 PH is a precipitation hardening martensitic stainless steel with Cu and Nb/Cb additions. The grade combines high strength, hardness (up to 572°F / 300°C), and corrosion resistance.
Mechanical properties can be optimized with heat treatment. Very high yield strength up to 1100-1300 MPa (160-190 ksi) can be achieved.
The grade should not be used at temperatures above 572°F (300°C) or at very low temperatures. It has adequate resistance to atmospheric corrosion or in diluted acids or salts where its corrosion resistance is equivalent to Alloy 304 or 430.
Alloy 17-4 PH withstands corrosive attacks better than any of the standard hardenable stainless steels and is comparable to Alloy 304 in most media.
If there are potential risks of stress corrosion cracking, the higher aging temperatures then must be selected over 1022°F (550°C), preferably 1094°F (590°C). 1022°F (550°C) is the optimum tempering temperature in chloride media.
1094°F (590°C) is the optimum tempering temperature in H2S media.
The alloy is subject to crevice or pitting attack if exposed to stagnant seawater for any length of time.
It is corrosion resistant in some chemical, petroleum, paper, dairy and food processing industries (equivalent to 304L grade).
If you would like to know more about 17-4PH stainless steel then click 17-4PH Technical Data.