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E: ssas@bssa.org.uk
E: ssas@bssa.org.uk
The basic design strength, py, is usually taken as the minimum specified 0.2% proof strength, given in the relevant product standard. Values for 0.2% proof strength and ultimate tensile strength for stainless steel sheet/strip and plate for grades typically used in structural applications are given below.
Minimum specified mechanical properties to BS EN 10088-2
| Type | Designation | Product form1 | Maximum thickness | 0.2% proof strength (N/mm2) | Ultimate tensile strength (N/mm2) |
|---|---|---|---|---|---|
| 304 | 1.4301 | C | 6 | 230 | 540/750 |
| H | 12 | 210 | 520/720 | ||
| P | 75 | ||||
| 304L | 1.4307 | C | 6 | 220 | 520/670 |
| H | 12 | 200 | |||
| P | 75 | 500/650 | |||
| 316 | 1.4401 | C | 6 | 240 | 530/680 |
| H | 12 | 220 | |||
| P | 75 | 520/670 | |||
| 316L | 1.4404 | C | 6 | 240 | 530/680 |
| H | 12 | 220 | |||
| P | 75 | 520/670 | |||
| Duplex 2205 | 1.4462 | C | 6 | 480 | 660/950 |
| H | 12 | 460 | |||
| P | 75 | 640/840 | |||
| Note 1) C=cold rolled strip, H=hot rolled strip, P=hot rolled plate |
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The modulus of elasticity of each of the grades given in the table is 200kN/mm2, Poissons ratio can be taken as 0.3 and the shear modulus is 76.9kN/mm2.
Physical properties of grades typically used in structural applications are given below.
Room temperature physical properties to BS EN 10088-1 (annealed condition)
| Grade | Steel designation | Density (kg/m3) | Thermal expansion 20 – 1000C (10-6/K) | Thermal conductivity (W/mK) | Heat capacity (J/kgK) |
|---|---|---|---|---|---|
| 304 | 1.4301 | 7900 | 16 | 15 | 500 |
| 304L | 1.4307 | ||||
| 316 | 1.4401 | 8000 | |||
| 316L | 1.4404 | ||||
| duplex 2205 | 1.4462 | 7800 | 13 |
In most respects, structural design in stainless steel is similar to design in carbon steel and requires comparable design checks and considerations. The only significant difference stems from the different shape of the stress-strain curve for stainless steels. Whereas carbon steel typically exhibits linear elastic behaviour up to yield stress and a plateau before strain hardening, stainless steel has a more rounded response with no well-defined yield stress.
This difference in stress-strain behaviour has implications on the buckling resistance (both local, flexural and lateral torsional) and deflections for stainless steel members. Buckling curves which are appropriate to the grade of stainless steel must therefore be used. Suitable methods must also be used for deflection calculations.
There is a comprehensive set of references for designing in stainless steel at:
Online Information Centre for Stainless Steel in Construction