The 17-4 stainless steel grade is an age-hardening martensitic alloy that combines high corrosion resistance and strength. Unlike conventional martensitic steels, it weldable by all standard methods, and achieves hardening with simple low-temperature treatment over a short period of time.
Alloy 17-4 is a chromium-copper precipitation hardening stainless steel that is used for applications requiring high strength and a moderate level of corrosion resistance. It is one of the most widely used precipitation hardening grades, as it has high strength hardness up to about 572°F while demonstrating good corrosion resistance in all heat treated conditions. Alloy 17-4 has adequate resistance to atmospheric corrosion or in diluted acid salts where its corrosion resistance is equivalent to Alloy 304 or 430. Alloy 17-4 can be heat treated to a variety of temperatures to develop a wide range of properties. Its mechanical properties can be optimized with heat treatment where very high yield strength up to 180 ksi can be achieved. Alloy 17-4 should not be used at temperatures above 572°F or at very low temperatures.
17-4 Stainless Steel
This martensitic precipitation hardening stainless steel has a combination of high hardness and strength after suitable heat treatment. It also has similar corrosion and heat resistance to Grade 304. The two terms "Type 630" and "17-4PH" refer to the same grade.
Carbon: 0.07 max
Manganese: 1.00 max
Phosphorus: 0.040 max
Sulfur: 0.030 max
Silicon: 1.00 max
Chromium: 15.00 - 17.50
Nickel: 3.00 - 5.00
Copper: 3.00 - 5.00
Melting Point: 2560 - 2625°F (1404 – 1440°C)
Density: 0.282 lbs/in3 / 7.8 g/cm3
Modulus of Elasticity in Tension: 28.5 X 106 psi / 197 GPa