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17-4PH Annealed

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.

17-4PH annealed stainless steel is commonly used for applications requiring high strength combined with moderate corrosion resistance. Industries and components frequently utilizing 17-4PH stainless steel include:

  • Aircraft: 17-4PH provides excellent strength-to-weight ratio, ensuring durability and reliability in critical aviation components.
  • Nuclear waste casks: 17-4PH offers reliable corrosion resistance and high mechanical strength necessary for safely storing hazardous materials long-term.
  • Paper mills: Annealed stainless steel withstands harsh chemical environments and mechanical stress, prolonging the lifespan of essential machinery and reducing maintenance downtime.
  • Oil fields: It delivers strong performance in challenging environments, resisting corrosion and stress cracking, crucial for drilling and extraction equipment.
  • Mechanical components: It’s ideal for gears, valves, and fasteners, thanks to its combination of toughness, high strength, and machinability.
  • Chemical process components: 17-4PH provides resilience against aggressive chemicals and moderate corrosion environments, supporting consistent performance and durability.
  • Food industry: Annealed stainless steel ensures clean operations, resists corrosion, and that it’s easy to clean. This makes it perfect for food processing equipment and machines.
  • Aerospace: 17-4PH demanding aerospace requirements by offering excellent mechanical properties, reliability under stress, and resistance to corrosive elements at high altitudes.

Adding 17-4PH annealed stainless steel into these applications ensures reliable performance, durability, and resistance to environmental and operational stresses.

Overview

General Properties

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

Applications:

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:

  • Aircraft
  • Nuclear waste casks
  • Paper mills
  • Oil fields
  • Mechanical components
  • Chemical process components
  • Food industry
  • Aerospace

Standards:

  • ASTM/ASME: UNS S17400
  • EURONORM: X5CrNiCuNb16.4
  • AFNOR: Z6CNU17-04
  • DIN: 1.4542
Resistance

Corrosion Resistance:

  • 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.
Properties

Weldability:

  • 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.

Machinability:

  • 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.
Properties

Chemical Composition

Carbon (C)Max Manganese (Mn)Max Silicon (Si)Max Chromium (Cr) Nickel (Ni) Copper (Cu) Phosphorus (P)Max Sulfur (S)Max
0.07 1 1 16.5-17.5 3-5 3-5 0.04 0.3

Mechanical Properties

Grade 17-4PH Annealed
Tensile Strength (MPa) 1100
Elongation A5 (%) 15
Proof Stress 0.2% (MPa) 1000
Elongation A5 (%) 15

Typical Physical Properties of Stainless Steels

Property Value
Density 7.75 kg/m^3
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