Overview
Type 304 is the most common austenitic stainless steel — often called "18/8" for its 18% chromium / 8% nickel composition. It offers excellent general corrosion resistance, good formability, and ease of fabrication. 304 is the baseline stainless grade for food processing, architectural, chemical, and general industrial applications where moderate corrosion resistance is needed.
Mechanical Properties
| Property | 304 (Annealed) | 304L (Low Carbon) |
|---|---|---|
| Density | 7,930 kg/m³ | 7,930 kg/m³ |
| Yield Strength (0.2%) | 205 MPa | 170 MPa |
| Ultimate Tensile | 515 MPa | 485 MPa |
| Elongation | 40% | 40% |
| Hardness | 180 BHN max | 180 BHN max |
| Young's Modulus | 193 GPa | 193 GPa |
Corrosion Resistance
304 provides excellent resistance to:
- Atmospheric environments (rural, urban, mild marine)
- Fresh water, steam
- Most organic chemicals, food products
- Oxidizing acids (nitric acid)
- Neutral and alkaline solutions
It is NOT suitable for:
- Chloride environments (seawater, brine, bleach) — causes pitting and crevice corrosion
- Chloride stress corrosion cracking (SCC) above ~60°C
- Reducing acids (hydrochloric, sulfuric at high concentrations)
- Long-term exposure above 425°C without low-carbon grade
Thermal Properties
| Property | Value |
|---|---|
| Melting Range | 1400-1455°C |
| Thermal Conductivity (100°C) | 16 W/m·K (much lower than carbon steel) |
| Specific Heat | 500 J/kg·K |
| Coefficient of Thermal Expansion | 17.2 × 10⁻⁶ /°C (~50% higher than carbon steel!) |
Applications
- Food processing equipment, brewing, dairy
- Architectural trim, building facades, handrails
- Kitchen equipment, appliances, sinks
- Chemical tanks (non-chloride), pharmaceutical equipment
- Process piping for clean water, steam, non-chloride chemicals
- Heat exchangers, fasteners, springs
Fabrication Notes
- 304 work-hardens rapidly; deep drawing may require intermediate annealing
- Weld with 308L filler (over-alloyed by ~2% Cr/Ni)
- Post-weld cleanup (pickling paste or mechanical) restores corrosion resistance
- Non-magnetic in annealed condition (can become slightly magnetic after cold work)
Summary
Type 304 (18/8, density 7930 kg/m³) is the general-purpose stainless steel for non-chloride environments. Use 304L for welded construction to avoid sensitization. Excellent formability, weldability, and general corrosion resistance. For marine, chloride, or reducing acid service, upgrade to 316L.
Related Engineering Tools
- Metal Weight Calculator Hub — Complete metal weight calculation hub
- Steel Weight Calculator — Steel plate, beam and section weight
- Aluminum Weight Calculator — Aluminum sheet and bar weight
- Copper Weight Calculator — Copper busbar and sheet weight
- Density Calculator — General density calculations
- Stainless Steel 316 — Upgrade grade for chloride service
- Corrosion Prevention Guide — Protect stainless in service
- Pipe Material Selection — Choose the right piping material
- Stainless Steel Weight Calculator — 304/316 weight
304 vs 316 vs 321 Stainless Comparison
| Property | 304 | 316 | 321 |
|---|---|---|---|
| Density | 7,930 kg/m3 | 7,990 kg/m3 | 7,930 kg/m3 |
| Yield Strength | 205 MPa | 205 MPa | 205 MPa |
| Tensile Strength | 520 MPa | 520 MPa | 520 MPa |
| Mo Content | 0% | 2-3% | 0% |
| Ti Content | 0% | 0% | 0.4% |
| Corrosion (atmospheric) | Excellent | Superior | Excellent |
| Pitting Resistance | Good | Excellent | Good |
| Max Temp (intermittent) | 870°C | 925°C | 870°C |
| Cost | Moderate | Higher | Higher |
Stainless Steel Weight Calculation
Example: 1000 x 1000 x 10mm 304 plate:
- W = 0.01 m3 x 7930 kg/m3 = 79.3 kg
- Compare: carbon steel = 78.5 kg (304 is 1% denser)
- Compare: aluminum = 27 kg (304 is 2.9x heavier)
304 Stainless Steel Properties by Temperature
| Temperature (°C) | Yield (MPa) | Tensile (MPa) | Elongation |
|---|---|---|---|
| 20 | 205 | 520 | 45% |
| 100 | 170 | 450 | 40% |
| 300 | 130 | 400 | 35% |
| 500 | 110 | 350 | 30% |
| 700 | 80 | 200 | 25% |
Frequently Asked Questions
What is the density of stainless steel 304? 304 stainless steel has a density of 7,930 kg/m3, approximately 1% denser than carbon steel (7,850 kg/m3). 316 stainless is slightly denser at 7,990 kg/m3.
Is 304 or 316 better for outdoor use? 316 is better for marine and coastal environments due to its 2-3% molybdenum content, which provides superior pitting and crevice corrosion resistance. 304 is sufficient for most atmospheric and freshwater applications.
What temperature can 304 stainless steel withstand? 304 stainless steel can operate intermittently up to 870°C and continuously up to 925°C. It maintains good oxidation resistance due to its 18% chromium content, which forms a protective oxide scale.
Is 304 stainless steel magnetic? 304 is non-magnetic in the annealed condition. It can become slightly magnetic after cold working (bending, drawing, machining) because cold work transforms some austenite to martensite.
What is the difference between 304 and 304L? 304L has a lower carbon content (max 0.03% vs 0.08%), which prevents chromium carbide precipitation (sensitization) during welding. Always specify 304L for welded assemblies to avoid intergranular corrosion in the heat-affected zone.
How much does 304 stainless steel weigh? 304 has a density of 7,930 kg/m³ — about 1% denser than carbon steel (7,850 kg/m³). A 1000 × 1000 × 10mm 304 plate weighs 79.3 kg, versus 78.5 kg for carbon steel and 27 kg for aluminum.