Stainless steel vs Weathering steel
Stainless steel and Weathering steel are commonly confused, and 2 measured properties separate them — density most clearly.
Stainless steel vs Weathering steel
Stainless steel
Steel with enough chromium to repair its own oxide film — the material that made corrosion a design choice rather than a certainty.
Weathering steel
Steel that rusts on purpose, and then stops — the material of unpainted bridges and rust-coloured sculpture.
| Property | Stainless steel | Weathering steel |
|---|---|---|
| Density | 7.7–8 g/cm³ | 7.8–7.9 g/cm³ |
| Electrical conductivity Only one of the two has a figure we can stand behind, so there is nothing to compare. | 1.45 MS/m | Not known |
| Melting point Only one of the two has a figure we can stand behind, so there is nothing to compare. | 1370–1450 °C | Not known |
| Tensile strength | 480–2000 MPa higher | 470–630 MPa |
Choosing between them
Weathering steel is recorded as a substitute for Stainless steel — cheaper.
What it gives up: Its patina needs alternating wet and dry cycles to form and is destroyed by chlorides — near the coast, or under road salt, it is simply the wrong material.
In this application, on the evidence cited above.
Why these get confused
both are 'steel that does not need painting', and one of them is covered in rust on purpose
The confusion is a real and documented one, not a resemblance we have invented.