Stainless Steel Plate

Most Widely Used Austenitic Stainless Steel Modified with a Controlled Carbon Chemistry for Increased Strength to 1500°F (816°C).

Available thicknesses for Alloy 304/304H:

3/16" 1/4" 5/16" 3/8" 7/16" 1/2" 9/16"
4.8mm 6.3mm 7.9mm 9.5mm 11.1mm 12.7mm 14.3mm
 
5/8" 3/4" 7/8" 1" 1 1/8" 1 1/4"
15.9mm 19mm 22.2mm 25.4mm 28.6mm 31.8mm

Alloy 304/304H (UNS S30400/ S30409) is a modification of the most widely utilized "18-8" chromium-nickel austenitic stainless steel. The carbon content is controlled in the range of 0.04-0.10% for increased strength at temperatures above 800°F (427°C). It is an economical and versatile corrosion resistant alloy suitable for a wide range of general purpose applications.

It is common practice for 304H to be dual certified as 304 and 304H. The high carbon chemistry of 304H enables 304 to meet the mechanical properties and grain size requirements of 304H.

Alloy 304/304H has general corrosion resistance similar to 304/304L. It resists atmospheric corrosion, as well as, moderately oxidizing and reducing environments. However, because of its high carbon content, Alloy 304/304H is subject to carbide precipitation in the heat affected zone of welds.

Alloy 304/304H is non-magnetic in the annealed condition, but can become slightly magnetic as a result of cold working or welding. It can be easily welded and processed by standard shop fabrication practices.

Specification Sheet Overview

for Alloy 304/304H (UNS S30400, S30409)
W. Nr. 1.4301:

Applications

  • Chemical and Petrochemical Processing-pressure vessels, tanks, heat exchangers, piping systems, flanges, fittings, valves and pumps
  • Petroleum Refining

Standards

ASTM.......................... A 240
ASME.......................... SA 240
AMS ........................... 5513
QQ-S .......................... 766

Corrosion Resistance

Alloy 304/304H has good resistance to atmospheric corrosion, foods and beverages and to many organic and inorganic chemicals in moderately oxidizing to moderately reducing environments. The high chromium content of the alloy provides resistance to oxidizing solutions such as nitric acid up to 55% weight and up to 176°F (80°C).

Alloy 304/304H also resists moderately aggressive organic acids such as acetic. The nickel present in the alloy provides resistance to moderately reducing solutions such as pure phosphoric acid, whatever the concentration, in cold solutions and up to 10% diluted hot solutions. The alloy can also operate successfully in caustic solutions free of chlorides or fluorides at moderate temperatures.

Alloy 304/304H does not perform well in more highly reducing environments such as those containing chlorides and sulfuric acid.

Alloy 304/304H performs well in fresh water service with low levels of chlorides (less than 100ppm). At higher chloride levels the grade is susceptible to crevice corrosion and pitting. For successful performance under these more severe conditions, higher molybdenum content is need such as 316/316L. Alloy 304/304H is not recommended for service in marine environments.

In most instances, the corrosion resistance of Alloys 304, 304L and 30H will be roughly equal in most corrosive environments. However, in environments that are sufficiently corrosive to cause intergranular corrosion of welds and heat-affected zones Alloy 304L should be used because of its low carbon content.

Lowest Temperature (°F) at Which the Corrosion Rate Exceeds 5mpy
CORROSION
ENVIRONMENT
Type
304/304H
Type
316L
2205
(UNS S32205)
2507
0.2% Hydrochloric Acid >Boiling >Boiling >Boiling >Boiling
1% Hydrochloric Acid 86p 86 185 >Boiling
10% Sulfuric Acid 122 140 167
60% Sulfuric Acid <54 <59 <57
96% Sulfuric Acid 113 77 86
85% Phosphoric Acid 176 203 194 203
10% Nitric Acid >Boiling >Boiling >Boiling >Boiling
65% Niitric Acid 212 212 221 230
80% Acetic Acid 212p >Boiling >Boiling >Boiling
50% Formic Acid ≤50 104 194 194
50% Sodium Hydroxide 185 194 194 230

83% Phosphoric Acid +
2% Hydrofluoric Acid

113 149 122 140
60% Nitric Acid +
2% Hydrocloric Acid
>140 >140 >140 >140
50% Acetic Acid +
50% Acetic Anhydride
>Boiling 248 212 230
1% Hydrochloric Acid +
0.3% Ferric Chloride
68p 77p 113ps 203ps
10% Sulfuric Acid +
2000ppm Cl- + N2
77 95 122
10% Sulfuric Acid +
2000ppm Cl- + SO2
<<59p <59 104
WPA1, High Cl- Content <<50 ≤50 113 203
WPA2, High F- Content <<50 ≤50 140 167

ps = pitting can occur
ps = pitting/crevice corrosion can occur

WPA P2O5 CL- F- H2SO4 Fe2O3 Al2O3 SiO2 CaO MgO
1 54 0.20 0.50 4.0 0.30 0.20 0.10 0.20 0.70
2 54 0.02 2.0 4.0 0.30 0.20 0.10 0.20 0.70

Chemical Analysis

Weight % (all values are maximum unless a range is otherwise indicated)

Element 304 304H
Chromium 18.0 min.-20.0 max. 18.0 min.-20.0 max.
Nickel 8.0 min.-10.5 max. 8.0 min.-10.5 max.
Carbon 0.08 0.04 min-0.10 max.
Manganese 2.00 2.00
Phosphorus 0.045 0.045
Sulfer 0.030 0.030
Silicon 0.75 0.75
Nitrogen 0.10 0.10
Iron Balance Balance

Physical Properties

Density

0.285 lbs/in3
7.90 g/cm3

Specific Heat

0.12 BTU/lb-°F (32 – 212°F)
502 J/kg-°K (0 – 100°C)

Modulus of Elasticity

29.0 x 106
200 GPa

 

Thermal Conductivity 212°F (100°C)

9.4 BTU/hr/ft2/ft/°F
16.3 W/m-°K

Melting Range

2550 – 2590°F
1398 – 1421°C

Electrical Resistivity

29.1 Microhm-in at 68°C
73 Microhm-cm at 20°C
Mean Coefficient of Thermal Expansion
Temperature Range  
°F °C in/in °F cm/cm °C
68-212 20-100 9.2 x 10-6 16.6 x 10-6
68-932 20-500 10.0 x 10-6 18.0 x 10-6
68-1600 20-870 11.0 x 10-6 19.8 x 10-6

Mechanical Properties

  ASTM
  Typical* Type 304 Type 304H
0.2% Offset Yield Strength, ksi 43 30 min. 30 min.
Ultimate Tensile Strength, ksi 91 75 min. 70 min.
Elongation in 2 inches, % 58 40 min. 140 min.
Reduction in Area, % 68
Hardness, Rockwell B 83 92 max. 92 max.

Fabrication Data

Alloy 304/304H can be easily welded and processed by standard shop fabrication practices.

Cold Forming

The alloy is quite ductile and forms easily. Cold working operations will increase the strength and hardness of the alloy and might leave it slightly magnetic.

Hot Forming

Working temperatures of 1652–2102°F (750–1150°C) are recommended for most hot working processes. For maximum corrosion resistance, the material should be annealed at 1900°F (1038°C) minimum and water quenched or rapidly cooled by other means after hot working.

Machining

Alloy 304/304H is subject to work hardening during deformation and is subject to chip breaking. The best machining results are achieved with slower speeds, heavier feeds, excellent lubrication, sharp tooling and powerful rigid equipment.

Operation Tool Lubrication CONDITIONS
      Depth-mm Depth-in Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Turning High Speed Steel Cutting Oil 6 .23 0.5 .019 13-18 42.6-59
Turning High Speed Steel Cutting Oil 3 .11 0.4 .016 20-25 65.6-82
Turning High Speed Steel Cutting Oil 1 .04 0.2 .008 26-31 85.3-101.7
Turning Carbide Dry or Cutting Oil 6 .23 0.5 .019 75-85 246-278.9
Turning Carbide Dry or Cutting Oil 3 .11 0.4 .016 90-100 295.3-328.1
Turning Carbide Dry or Cutting Oil 1 .04 0.2 .008 110-120 360.8-393.7
      Depth of cut-mm Depth of cut-in Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Cutting High Speed Steel Cutting Oil 1.5 .06 0.03-0.05 .0012-.0020 18-23 59-75.5
Cutting High Speed Steel Cutting Oil 3 .11 0.04-0.06 .0016-.0024 19-24 62.3-78.7
Cutting High Speed Steel Cutting Oil 6 .23 0.05-0.07 .0020-.0027 20-25 65.6-82
      Drill ø mm Drill ø in Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Drilling High Speed Steel Cutting Oil 1.5 .06 0.02-0.03 .0007-.0012 10-14 32.8-45.9
Drilling High Speed Steel Cutting Oil 3 .11 0.05-0.06 .0020-.0024 12-16 39.3-52.5
Drilling High Speed Steel Cutting Oil 6 .23 0.08-0.09 .0031-.0035 12-16 39.3-52.5
Drilling High Speed Steel Cutting Oil 12 .48 0.09-0.10 .0035-.0039 12-16 39.3-52.5
          Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Milling Profiling High Speed Steel Cutting Oil     0.05-0.10 .002-.004 12-22 39.4-72.2

Welding

Alloy 304/304H can be readily welded by most standard processes. After welding Alloy 304/304H it may be necessary to anneal the plate to restore the corrosion resistance lost by sensitization to intergranular corrosion when chromium carbides precipitate in the grain boundaries in the weld heat-affected zone.

NOTE: The information and data in this product data sheet are accurate to the best of our knowledge and belief, but are intended for informational purposes only, and may be revised at any time without notice. Applications suggested for the materials are described only to help readers make their own evaluations and decisions, and are neither guarantees nor to be construed as express or implied warranties of suitability for these or other applications.

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