904L Stainless

904L Stainless

Nickel (Ni) - 25.5
Copper (Cu) - 1.5
Chromium (Cr) - 20.5
Molybdenum (Mo) - 1.5
Iron (Fe) - 45.0
Manganese (Mn) - 1.0
Other

Key

Nickel
Copper
Chromium
Aluminum
Molybdenum
Iron
Titanium
Manganese
Cobalt
Other
  • Nickel (Ni) 25.5
  • Copper (Cu) 1.5
  • Chromium (Cr) 20.5
  • Molybdenum (Mo) 1.5
  • Iron (Fe) 45.0
  • Manganese (Mn) 1.0
  • Carbon (C) 0.01
  • Silicon (Si) 0.5
  • Phosphorus (P) 0.02
  • Sulfur (S) 0.02

UNS N08904

904L Stainless is the most common of the “4% Molybdenum” alloys. It was designed to be an upgrade to 316L and Alloy 20 without incurring the expense of Alloy C276. 904L Stainless has been surpassed in popularity by the “6% Molybdenum” alloys such as AL6XN®. Its availability in round bar is limited to metric sizes in 5mm increments. Consequently, inch-size diameter-headed bolts are relatively expensive to manufacture.

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Summary

  • Environment:
    Moderately Corrosive: Acids & Chemicals
  • Temperature Limit:
    850 °F / 454 °C
  • Ultimate Tensile (Typical):
    88 ksi / 605 mpa

Specifications & Technical Data

If your question isn’t answered below, download the complete technical data sheet here.

Specifications

  • Plate, Sheet & Strip: ASTM A240
  • ASTM B625

Physical Properties

Density lb/in3 0.287
g/cm3 7.95
Specific Heat Btu/lb•°F (32-212°F) 0.11
J/kg•°C (0-100°C) 450
Electrical Resistivity Microhm-in at 68°F 33.5
Microhm-cm at 20°C 95.2
Modules of Elasticity x 106 psi 28.0
GPa 190
Melting Range °F 2372 – 2534
°C 1300 – 1390
Thermal Conductivity Btu•in/ft2 •h•°F 85
W/m•°C 12.3
Specific Gravity 7.95
Magnetic Permeability <1.02

 

Mean Coefficient of Thermal Expansion
Temperature Range
°F °C in/in/°F cm/cm/°C
68 – 212 20 – 100 8.5 x 10-6 15.3 x 10-6
68- 750 20-400 9.2 x 10-6 16.5 x 10-6
68-1475 20-800 10.1 x 10-6 18.2 x 10-6

Mechanical Properties

  Yield Strength (0.2% Offset) Ultimate Tensile Strength Elongation in 2 in. Hardness
psi MPa psi MPa % Rockwell B
Minimum ASTM & ASME 31,000 220 71,000 490 36 70 – 90
Typical Value 39,500 270 88,000 605 50 79

Typical Values at 68°F (20°C) (minimum values, unless specified)

Maximum Allowable Stress per ASME
Maximum Metal Temperatures Maximum Allowable Stress per ASME
°F °C ksi MPa
100 38 17.8 123
200 93 16.7 115
300 149 15.1 104
400 204 13.8 95
500 260 12.7 88
600 316 12.0 83
700 371 11.4 79

Corrosion Rates

General Corrosion
Boiling Solution Corrosion Rate in MPY (mm/a)
Steel Grade 316 Steel Grade 904L
20% Acetic Acid 0.1 (<0.01) 0.6 (0.02)
45% Formic Acid 10.9 (0.28) 7.7 (0.20)
1% Hydrochloric Acid 226 (5.74) 21.6 (0.55)
10% Oxalic Acid 40.1 (1.02) 27.1 (0.69)
20% Phosphoric Acid 0.20 (<.01) 0.5 (0.01)
10% Sodium Bisulfate 41.5 (1.06) 8.9 (0.23)
50% Sodium Hydroxide >100 (>2.5) 9.6 (0.24)
10% Sulfamic Acid 63.6 (1.62) 9.1 (0.23)
10% Sulfuric Acid 636 (16.2) 101 (2.57)

 

Pitting Corrosion in 10% Ferric Chloride
Alloy Temperature of Onset of
Crevice Corrosion Attack*, °F (°C)
316 27 (-3)
317 35 (2)
904L 65 (18)
AL-6XN 113 (45)
625 113 (45)
AL 29-4C 125 (52)

*ASTM Procedure G-48, 10% Ferric Chloride Solution.

Chloride Stress Corrosion Cracking
Samples and Test Times to 1000 Hours
Boiling Solution Alloy 316 Alloy 904L Alloy 20
42% Magnesium Chloride Fail Fail Fail
33% Lithium Chloride Fail Fail Pass
26% Sodium Chloride Fail Pass Pass

Fail = Chloride stress corrosion cracks observed. Pass = No cracking observed in testing.

Intergranular Corrosion
Intergranular Corrosion Resistance Test Procedure Corrosion, Rates Mils per Year, (mm/a)
Alloy 316 Alloy 904L
Copper-Copper Sulfate
16% Sulfuric Acid
(ASTM A262 Practice E) Evaluated by Bend Test
No Fissures No Fissures
Ferric Sulfate
Sulfuric Acid
(ASTM A262 Practice B)
35.5
(0.90)
14.2
(0.36)
65% Nitric Acid
(ASTM A262 Practice C)
34.3
(0.87)
15.4
(0.39)

 

Uniform corrosion in pickling acid* at 25°C
Steel Grade Corrosion Rate, mm/year
316L >6
904L 0.47
254 SMO® 0.27
654 SMO® 0.06

*Composition: 20% HNO3 + 4% HF.

Uniform corrosion in wet process phosphoric acid at 60°C
Steel Grade Corrosion Rate, mm/year
316L >5
904L 1.2
254 SMO® 0.05

Composition: 54% P2O5, 0.06% HCl, 1.1% HF, 4.0% H2SO4, 0.27% Fe2O3, 0.17% Al2O3, 0.10% SiO2, 0.20% CaO and 0.70% MgO.

Corrosion rates in a fatty acid column for the distillation of tall oil at 253°C
Steel Grade Corrosion Rate, mm/year
316L 0.88
317LMN 0.29
904L 0.06
254 SMO® 0.01
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