Stainless steel density acts as a important factor in material selection for engineering design and quality control. Stainless steel density falls within the range of 7.5 to 8.0 g/cm³ (0.27 to 0.29 lb/cu in), depending on composition.
For example, Stainless Steel 304, a widely used alloy with 18% chromium and 8% nickel, has a density of approximately 7.93 g/cm³. In comparison, Stainless Steel 316, which contains 16-18% chromium, 10-14% nickel, and 2-3% molybdenum, has a slightly higher density of 7.98 g/cm³ due to its composition.
Key Factors Affecting Stainless Steel Density
The density of stainless steel depends on many factors including alloying elements, manufacturing process, microstructure, etc.
Alloying Composition
Stainless steel having high-density metal will have higher density; for if it possesses a high %age of nickel or molybdenum, it will show higher density. 410 stainless steel possesses 11 to 13% chromium and has a relatively lower density of about 7800 kg/m³ than austenitic grade steel due to the absence of nickel.
Manufacturing Process
The density of stainless steel is also affected by its manufacturing process. For example, Sintered stainless steel made by powder metallurgy has a porous structure, which lowers its overall density.
Microstructure
The density of stainless steel is directly influenced by the phases and arrangements of atoms within its microstructure. For instance, austenitic stainless steels have a face-centred cubic (FCC) crystal structure. FCC structure exhibits a more closely packed atomic arrangement, resulting in higher density. In contrast, ferritic and martensitic stainless steels have a body-centred cubic (BCC) structure, which is less densely packed. This results in marginally lower densities compared to austenitic grades.
How to Calculate the Density of Stainless Steel?
To calculate the density of stainless steel with precision, first of all, the mass of the sample is measured. It is done by using a digital balance with at least 0.01 g accuracy. Now, volume calculation is done. For samples with regular geometry, volume can be determined by measuring dimensions and applying geometric formulas.
For irregular shapes, use the Archimedes’ principle. Alternatively, a liquid pycnometer or gas pycnometer may be used to measure volume with accuracies of 0.02–0.03%. You can also measure volume by Gamma-ray densitometry, which is suited for non-destructive, large-scale applications. Once both mass and volume are known, apply the formula to obtain density: ρ = m/v
Stainless Steel Density Conversion
Based on industrial requirements, one can convert density stainless steel into various units.
Here is how we get density of stainless steel in lb in3
| Unit Conversion | Conversion Factor | Result (for 7.75 g/cm³) |
|---|---|---|
| g/cm³ → kg/m³ | × 1000 | 7750 kg/m³ |
| g/cm³ → lb/in³ | × 0.036127 | 0.280 lb/in³ |
| g/cm³ → lb/ft³ | × 62.43 | 484 lb/ft³ |
Density of Stainless Steel Grades
Based on the composition and alloying materials, the mass density of stainless steel varies.
304 vs 316 Stainless Steel
| Property | 304 Stainless Steel | 316 Stainless Steel |
|---|---|---|
| Density (g/cm³) | 7.93 g/cm³ | 7.98 g/cm³ |
| Composition | 18% Cr, 8% Ni | 16–18% Cr, 10–14% Ni, 2–3% Mo |
| Corrosion Resistance | Good resistance to oxidation and corrosion | Superior resistance, especially against chlorides |
| Strength & Durability | High tensile strength, commonly used in structural applications | Stronger in extreme conditions, ideal for marine and chemical industries |
| Common Applications | Kitchenware, food processing, architectural uses | Marine, medical, and chemical processing equipment |
The following table shows the density of different grades of stainless steel.
| Stainless Steel Type | Grade Examples | Density (g/cm³) | Density (kg/m³) | Density (lb/in³) |
|---|---|---|---|---|
| Austenitic Stainless Steel | 304, 316, 310, 321, 904L | 7.90 – 8.00 | 7900 – 8000 | 0.286 – 0.289 |
| Ferritic Stainless Steel | 409, 430, 439, 444 | 7.70 – 7.80 | 7700 – 7800 | 0.278 – 0.282 |
| Martensitic Stainless Steel | 410, 420, 431, 440C | 7.65 – 7.80 | 7650 – 7800 | 0.276 – 0.282 |
| Duplex Stainless Steel | 2205, 2507, LDX 2101 | 7.80 – 7.85 | 7800 – 7850 | 0.282 – 0.284 |
Density of Stainless Steel vs Aluminum
Here is the comparison of stainless steel density and aluminium
Mass Density and Structural Implications
Aluminum has a lower density compared to steel. For example, its alloy 6061-T6 shows a density of 2.70 g/cm, which is one-third the density of steel. Due to its low density, Al is considered ideal for manufacturing lightweight components.
Impact of Alloying Elements
The high density of steel is due to its alloying elements like chromium, nickel, and molybdenum. In contrast, aluminium alloys contain copper and magnesium, which have lower densities.
Practical Applications
Strength and Durability
High-density stainless steels such as 304, 316, offer excellent mechanical strength. These steels are considered ideal for structural applications such as manufacturing heavy-duty machinery and load-bearing components.
Weight Considerations
Lower-density grades like ferritic stainless steel are preferred for lightweight applications.
Thermal and Electrical Properties
The weight density of stainless steel also affects its thermal expansion and conductivity. These properties influence suitability for heat exchangers, piping, and electrical enclosures.
FAQ
1. What is the Density of 17-4 PH Stainless Steel?
The density of 17-4 PH stainless steel is 7.80 to 7.90 g/cm³. It is a precipitation-hardening stainless steel known for its high strength and corrosion resistance.
2. What is the Density of 18-8 Stainless Steel?
18-8 stainless steel has a density of 7.93 g/cm³ (7,930 kg/m³ or 0.286 lb/in³), widely used in corrosion-resistant applications.
3. What is the Density of 15-5 PH Stainless Steel?
15-5 PH stainless steel has a density of 7.80 g/cm³ (7,800 kg/m³ or 0.282 lb/in³).
