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17-4PH H900

Available upon request: Alloy 17-4 (H900, UNS S17400) in sheet, sheet coil, plate, round bar, processed flat bar and tubular products.

 

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

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.

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.

Chemical Properties:

TYPE Cr Ni Cu Cb + Ta C Mn P S Si
17-4 (H900) min: 15.0
max: 17.5
min: 3.0
max: 5.0
min: 3.0
max: 5.0
min: 0.15
max: 0.45
0.07
max
1.00
max
0.04
max
0.03
max
1.00
max

Mechanical Properties:

Hardening or Precipitation Treatment at 900°F
Thickness,
inches
Ultimate Tensile
Strength, ksi min.
0.2% Yield
Strength, ksi min.
Elongation % in 2″ min. Reduction in Area min. % Hardness,
Rockwell,
min. / max
Hardness, Brinell,
min. / max.
Under 0.1875″ 190 170 5 C40 – C48
0.1875″ to
0.625″
190 170 8 25 C40 – C48 388 / 477
0.625″ to 4.0″ 190 170 10 30 C40 – C48 388 / 477

Hardening or Aging Treatment at 900°F
Thickness,
inches
Ultimate Tensile
Strength, ksi min.
0.2% Yield
Strength, ksi min.
Elongation % in 2″ min. Reduction in Area min. % Hardness,
Rockwell,
min. / max
Hardness, Brinell,
min. / max.
Up to 3.0 in. incl. 190 170 10 40 40 388
Over 3.0 in. to
8.0 in. incl.
190 170 8 35 40 388

Physical Properties:

Heat Treated Condition H900
Density, lbs/in3 0.282
Electrical Resistivity, microhm-cm 77
Specific Heat, BTU/lb/°F (32-212°F) 0.10
Thermal Conductivity, BTU/hr/ft2/in/°F
300°F 124
500°F 135
860°F 156
900°F 157
Mean Coefficient of Thermal Expansion, in/in/°F
-100 to 70°F 5.8 x 10-6
70 – 200°F 6.0 x 10-6
70 – 400°F 6.0 x 10-6
70 – 600°F 6.3 x 10-6
70 – 800°F 6.5 x 10-6
70 – 900°F
Modulus of Elasticity, ksi 28.5 x 103
Modulus of Rigidity, ksi 11.2 x 103
Poisson’s Ratio (all conditions) 0.272

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