Young's Modulus of Type 304 Stainless Steel

Austenitic stainless steels are face-centred cubic rather than body-centred cubic, but at room temperature the change of crystal structure barely touches stiffness: NIST's fit to measured 304 data gives 199.5 GPa at 20 °C, and published design values run a few percent lower. For most work the difference from carbon steel is noise, and designers reach for the same 29 000 ksi. Where a few percent shows up is in precision positioning, spring rates and long, slender stainless members.

The bigger differences between stainless and carbon steel are elsewhere. Stainless expands about 30 % more per degree at room temperature (15.4 vs 11.7 µm/m·K) and more as it heats, conducts heat less than a third as well, and work-hardens aggressively, so cold-formed and cold-drawn stainless has a yield strength far above its annealed value. Take this modulus as annealed sheet and bar at room temperature; duplex and precipitation-hardening grades run 195–200 GPa, and all of them soften with temperature.