Home / Resources / Product Information / Stainless Grades / Precipitation Hardening Grades /
Penn Stainless inventory now includes Alloy 17-4 (Alloy 630, UNS S17400) in sheet, plate, round bar, and true bar. Custom 17-4PH tubular products available upon request.
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.
Specifications: UNS S17400
Alloy 17-4 is commonly used for applications requiring high strength and a moderate level of corrosion resistance. Some applications that frequently use Alloy 17-4 include:
- Nuclear waste casks
- Paper mills
- Oil fields
- Mechanical components
- Chemical process components
- Food industry
- ASTM/ASME: UNS S17400
- EURONORM: X5CrNiCuNb16.4
- AFNOR: Z6CNU17-04
- DIN: 1.4542
- Withstands corrosive attacks better than any of the standard hardenable stainless steels.
- Comparable to Alloy 304 in most media.
- Corrosion resistant in some chemical, petroleum, dairy, and food process industries.
- Subject to crevice or pitting attack if exposed to stagnant sea water for any length of time.
- Successfully welded by most common fusion and resistance methods.
- Should not be joined by oxyacetylene welding.
- Generally no pre-heating required.
- Inter-pass temperature must be limited to 248°F.
- Better toughness is obtained in the weld after a complete heat treatment.
Elevated Temperature Use:
- Excellent resistance to oxidation to approximately 1100°F.
- Long-term exposure to elevated temperature can result in reduced toughness in the precipitation hardened conditions.
Processing – Hot Forming:
- To forge, heat uniformly to 2150 / 2200°F and hold for half hour per inch.
- Preferred temperature range for hot forming is at 650-900°F, while the steel is still austenitic.
- To ensure the best condition for the hardening operations, the forgings must be re-heat treated at 1875-1925°F.
- Cool forgings to below 90°F to ensure grain refinement.
Processing – Cold Forming:
- Alloy 17-4 is limited to mild operations since in the annealed (solution treated) condition the material is hard.
- For severe cold working the material should be heat treated to condition H1150. This will help prevent possible cracking.
- Bend radius in excess of 7T is often required.
- To improve stress corrosion resistance after cold forming, re-aging at the precipitation-hardening temperature is recommended.
- Can be machined in both solution-treated and precipitation-hardening conditions.
- Machining conditions may vary with hardness of material.
- High-speed tools or preferably carbide tools with standard lubrication are normally used.
|Carbon (C)Max||Manganese (Mn)Max||Silicon (Si)Max||Chromium (Cr)||Nickel (Ni)||Copper (Cu)||Phosphorus (P)Max||Sulfur (S)Max|
|Tensile Strength (MPa)||1100|
|Elongation A5 (%)||15|
|Proof Stress 0.2% (MPa)||1000|
|Elongation A5 (%)||15|
Typical Physical Properties of Stainless Steels
|Modulus of Elasticity||196 GPa|
|Electrical Resistivity||0.080×10^-6 Ω.m|
|Thermal Conductivity||18.4 W/m.K|
|Thermal Expansion||10.8×10^-6 /K|