304/304H Stainless Steel Plate
High-Temperature Corrosion Resistant Alloy for Industrial Applications
Available thicknesses for Alloy 304/304H
Imperial (inches) | Metric (mm) | Imperial (inches) | Metric (mm) |
3/16″ | 4.8 | 1 1/4″ | 31.8 |
1/4″ | 6.3 | 1 3/8″ | 34.9 |
5/16″ | 7.9 | 1 1/2″ | 38.1 |
3/8″ | 9.5 | 1 5/8″ | 41.3 |
7/16″ | 11.1 | 1 3/4″ | 44.5 |
1/2″ | 12.7 | 2″ | 50.8 |
9/16″ | 14.3 | 2 1/4″ | 57.2 |
5/8″ | 15.9 | 2 1/2″ | 63.5 |
3/4″ | 19.0 | 2 3/4″ | 69.9 |
7/8″ | 22.2 | 3″ | 76.2 |
1″ | 25.4 | 3 1/4″ | 82.6 |
1 1/8″ | 28.6 | 3 1/2″ | 88.9 |
|
| 3 3/4″ | 95.3 |
|
| 4″ | 101.6 |
|
| 4 1/4″ | 108.0 |
|
| 4 1/2″ | 114.3 |
|
| 4 3/4″ | 120.7 |
|
| 5″ | 127.0 |
|
| 5 1/4″ | 133.4 |
|
| 5 1/2″ | 139.7 |
|
| 5 3/4″ | 146.1 |
|
| 6″ | 152.4 |
Product Overview
304/304H (UNS S30400/S30409) is an improved version of 18-8 chromium-nickel stainless steel.
Controlled carbon content (0.04-0.10%) for better strength at high temps (up to 816°C / 1500°F).
Cost-effective and versatile for chemical, oil & gas, and food processing industries.
Can be dual-certified as 304 and 304H.
Specification Sheet Overview
Chemical Analysis
Element | 304 Specification | 304H Specification |
Chromium (Cr) | 18.0-20.0% | 18.0-20.0% |
Nickel (Ni) | 8.0-10.5% | 8.0-10.5% |
Carbon (C) | ≤0.08% | 0.04-0.10% |
Manganese (Mn) | ≤2.00% | ≤2.00% |
Phosphorus (P) | ≤0.045% | ≤0.045% |
Sulfur (S) | ≤0.030% | ≤0.030% |
Silicon (Si) | ≤0.75% | ≤0.75% |
Nitrogen (N) | ≤0.10% | ≤0.10% |
Iron (Fe) | Balance | Balance |
Key Features:
The chromium content (18-20%) provides excellent oxidation resistance
Nickel content (8-10.5%) ensures good formability and toughness
The main difference is in carbon content: 304H has controlled higher carbon (0.04-0.10%) for improved high-temperature strength
All other elements are maintained at similar levels for consistent performance
Note: All values are maximum percentages unless specified as a range. The actual balance is iron with minor trace elements.
Corrosion Resistance
Corrosive Environment | 304/304H | Notes |
0.2% Hydrochloric Acid | >Boiling | Good resistance |
1% Hydrochloric Acid | 86°F (p) | Pitting risk above this temp |
10% Sulfuric Acid | — | Not recommended |
60% Sulfuric Acid | — | Not recommended |
96% Sulfuric Acid | — | Not recommended |
85% Phosphoric Acid | 176°F | Suitable for cold/mild temps |
10% Nitric Acid | >Boiling | Excellent resistance |
65% Nitric Acid | 212°F | Good resistance |
80% Acetic Acid | 212°F (p) | Pitting risk above this temp |
50% Formic Acid | ≤50°F | Limited resistance |
50% Sodium Hydroxide | 185°F | Suitable for moderate temps |
83% H₃PO₄ + 2% HF | 113°F | Limited resistance |
60% HNO₃ + 2% HCl | >140°F | Moderate resistance |
50% Acetic Acid + 50% Acetic Anhydride | >Boiling | Good resistance |
1% HCl + 0.3% FeCl₃ | 68°F (p) | High pitting risk |
10% H₂SO₄ + 2000ppm Cl⁻ + N₂ | — | Not recommended |
10% H₂SO₄ + 2000ppm Cl⁻ + SO₂ | — | Not recommended |
WPA1 (High Cl⁻ Content) | <50°F | Poor chloride resistance |
WPA2 (High F⁻ Content) | <50°F | Poor fluoride resistance |
Key:
(p): Pitting/crevice corrosion possible above this temperature.
—: Not suitable for this environment.
WPA: Wet process phosphoric acid conditions.
Summary:
Best for: Nitric acid, acetic acid, phosphoric acid (dilute/cold).
Avoid: Hydrochloric/sulfuric acids, high chloride/fluoride environments.
Welding: Post-weld annealing recommended to restore corrosion resistance.
Physical Properties
Property | Imperial Units | Metric Units |
Density | 0.285 lb/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 × 10⁶ psi | 200 GPa |
Thermal Conductivity (at 212°F/100°C) | 9.4 BTU·in/hr·ft²·°F | 16.3 W/m·K |
Melting Range | 2550-2590°F | 1398-1421°C |
Electrical Resistivity | 29.1 μΩ·in (at 68°F) | 73 μΩ·cm (at 20°C) |
Mechanical Properties
Property | ASTM Specification | Typical Value | 304 Minimum | 304H Minimum |
0.2% Offset Yield Strength | ksi | 43 | 30 | 30 |
Ultimate Tensile Strength | ksi | 91 | 75 | 70 |
Elongation in 2 inches | % | 58 | 40 | 40 |
Reduction in Area | % | 68 | – | – |
Hardness | Rockwell B | 83 | 92 max | 92 max |
Thermal Expansion Characteristics
| Temperature Range | Coefficient of Thermal Expansion | ||
|---|---|---|---|
| °F | °C | in/in·°F | cm/cm·°C |
| 68-212 | 20-100 | 9.2 × 10⁻⁶ | 16.6 × 10⁻⁶ |
| 68-932 | 20-500 | 10.0 × 10⁻⁶ | 18.0 × 10⁻⁶ |
| 68-1600 | 20-870 | 11.0 × 10⁻⁶ | 19.8 × 10⁻⁶ |
Important Notes:
The physical properties are essentially identical for both 304 and 304H grades
These characteristics make the material suitable for applications requiring good thermal stability and electrical resistance
The thermal expansion data is particularly important for high-temperature applications
All values are typical at room temperature unless otherwise specified
These physical properties, combined with its excellent corrosion resistance, make 304/304H stainless steel a versatile choice for various industrial and commercial applications.
Fabrication Data
Cold Forming
High ductility allows for easy forming
Cold working increases strength and hardness
May develop slight magnetism after forming
Annealing recommended for severe deformations
Hot Forming Parameters
Parameter | Specification |
Working Temperature Range | 750-1150°C (1382-2102°F) |
Recommended Annealing Temperature | Min. 1038°C (1900°F) |
Cooling Method | Water quench or rapid cooling |
Machining Guidelines
Optimal conditions for common machining operations:
Turning Operations
Tool Material | Depth of Cut | Feed Rate | Speed | Lubrication |
High Speed Steel | 1-6mm (0.04-0.23″) | 0.2-0.5mm/rev (0.008-0.019″/rev) | 13-31 m/min (42-101 ft/min) | Cutting Oil |
Carbide | 1-6mm (0.04-0.23″) | 0.2-0.5mm/rev (0.008-0.019″/rev) | 75-120 m/min (246-393 ft/min) | Dry or Oil |
Drilling Operations
Drill Diameter | Feed Rate | Speed | Lubrication |
1.5-12mm (0.06-0.48″) | 0.02-0.10mm/rev (0.0007-0.0039″/rev) | 10-16 m/min (33-53 ft/min) | Cutting Oil |
Milling
Feed: 0.05-0.10mm/tooth (0.002-0.004″/tooth)
Speed: 12-22 m/min (39-72 ft/min)
Lubrication: Cutting oil required
Welding Considerations
Compatible with all standard welding methods
Post-weld annealing recommended to restore full corrosion resistance
May require low-carbon filler material for critical applications
Control heat input to minimize carbide precipitation
Common Applications
Food Processing Equipment
- Brewery tanks
- Dairy processing machinery
- Food preparation surfaces
Chemical & Petrochemical Industry
- Storage tanks
- Heat exchangers
- Pressure vessels
Architectural & Construction
- Wall cladding
- Elevator panels
- Structural components
Industrial Equipment
- Pharmaceutical machinery
- Textile processing equipment
- Water treatment systems
High-Temperature Applications (304H specifically)
- Boiler components
- Furnace parts
- Heat recovery systems
Standards & Certifications
ASTM: A240 (Standard Specification for Chromium and Chromium-Nickel SS Plate)
ASME: SA-240 (Pressure Vessel Quality)
EN: 1.4301 (304) / 1.4948 (304H)
AMS: 5513 (Aerospace Material Specification)
FAQ
What is the difference between 304 and 304H stainless steel plates?
304: Max 0.08% carbon (standard grade for general corrosion resistance)
304H: 0.04–0.10% carbon (higher carbon for improved high-temperature strength)
Key Notes:
✔ 304H is often dual-certified as 304 (meets both standards)
✔ 304H is preferred for temps above 500°F (260°C) (e.g., boilers, heat exchangers)
✔ 304 is better for welding (lower carbon reduces carbide precipitation risk)
Can 304/304H stainless steel plates be used in marine environments?
Not recommended for long-term marine use.
Resists mild atmospheric corrosion (coastal areas with proper maintenance)
Not suitable for submerged or high-salt environments (risk of pitting/crevice corrosion)
Better Alternatives:
➔ 316/L (higher molybdenum – better chloride resistance)
➔ Duplex steels (e.g., 2205 for harsh marine conditions)
Note: Regular cleaning and passivation can improve performance in mild marine exposures.
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