Density of 1.4404 Stainless Steel: Values, Conversions and Mass Calculation

Density of 1.4404 in Common Units

1.4404 is the EN designation for X2CrNiMo17-12-2, the molybdenum-bearing austenitic stainless steel known in the American system as AISI 316L and UNS S31603. Its density at room temperature is 7.99 g/cm3. Converted to the units used by different markets, that is:

The value is quoted at 20 degrees C. Density falls very slightly as temperature rises because the lattice expands, but the change is small enough to be ignored in ordinary engineering calculations up to a few hundred degrees. For most purposes 7.99 g/cm3, rounded to 8.0 g/cm3, is used in design software and weight tables.

Composition and Why Density Differs Between Grades

The composition ranges that give 1.4404 its density are a maximum carbon content of 0.030 %, chromium 16.5 to 18.5 %, nickel 10.0 to 13.0 % and molybdenum 2.00 to 2.50 % in the EN specification, with corresponding ranges of chromium 16.0 to 18.0 %, nickel 10.0 to 14.0 % and molybdenum 2.00 to 3.00 % in the ASTM A240 table for UNS S31603. The atomic masses of the alloying elements, particularly the substitution of heavier molybdenum for iron, explain why the austenitic grades are denser than ferritic and martensitic grades. Nitrogen, by contrast, is a light interstitial element and has almost no effect at the levels permitted in 316L.

Density Comparison Across Common Stainless Grades

The spread between structural carbon steel and 1.4404 is only about 1.8 %, which is one reason stainless steel is often quoted by weight and priced by the kilogram rather than by volume. Against a duplex grade such as 2205 the difference reaches roughly 2.4 %, and against titanium the comparison is more dramatic: a titanium component weighs about 56 % of the same component in 1.4404.

Calculating Mass from Density

For flat product, the mass per square metre is the density multiplied by the thickness in millimetres, so 1.4404 plate 5 mm thick weighs 7.99 x 5 = 39.95 kg/m2. For round bar, mass per metre in kilograms is the density in g/cm3 multiplied by the cross-sectional area in square millimetres, divided by 1273.24. A simpler working form for round bar in kilograms per metre uses the diameter in millimetres: mass = 0.00628 x d2. For seamless pipe, where the wall thickness is significant relative to the diameter, the accurate form is mass per metre in kilograms = 0.0251 x t x (OD - t), with outside diameter OD and wall thickness t in millimetres, which follows directly from a density of 7.99 g/cm3. Using the figure for 304 (0.0248) on a 316L order under-runs the calculated weight by about 1.2 %, which is enough to matter on a large tonnage order.

Where the Density Value Is Used

Density appears in more calculations than most buyers expect. It converts a bar or pipe schedule into order weight and freight weight. It sets the self-weight used in structural and support design, and the buoyancy term in immersed applications. It is used to check the allowable stresses and the hydrostatic test pressure in pressure vessel calculations. It supports the pricing of scrap and the conversion of volume-based stock counts into tonnes. And in purchasing, it is the basis on which a mill or stockholder converts theoretical weight into actual weight when a tolerance applies to thickness or wall.

Frequently Asked Questions

Q: What is the density of 1.4404 stainless steel?
A: 7.99 g/cm3, equivalent to 7990 kg/m3, 0.289 lb/in3 or 499 lb/ft3, quoted at room temperature.

Q: Is 1.4404 the same as 316L?
A: Yes. 1.4404 (X2CrNiMo17-12-2) corresponds to AISI 316L and UNS S31603, with carbon limited to 0.030 % maximum.

Q: Why is 316L denser than 304?
A: The molybdenum addition, at 2.0 to 2.5 %, replaces lighter iron atoms in the lattice, raising the density from about 7.93 g/cm3 for 304 to 7.99 g/cm3 for 316L.

Q: Does heat treatment change the density of 1.4404?
A: No. Solution annealing changes the microstructure and removes residual stress, but the density of the solid remains essentially 7.99 g/cm3.

Q: How do I calculate the weight of a 1.4404 pipe?
A: Use mass per metre in kilograms = 0.0251 x wall thickness x (outside diameter minus wall thickness), with all dimensions in millimetres at a density of 7.99 g/cm3.

Q: What density should be used for a 1.4404 bar order?
A: 7.99 g/cm3. For round bar, mass per metre in kilograms is 0.00628 x diameter squared, with the diameter in millimetres.