Material selection
Mild Steel vs Stainless 304
Mild steel (CRCA) is the cheapest formable sheet metal there is, and Stainless 304 costs more to buy and more to machine. The decision is almost never about strength, the two are close, it is about what happens to the surface over the part's service life and who has to maintain it. The numbers below are the same published values used on each material's own page, set side by side.
| Mild steel (CRCA) | Stainless 304 | |
|---|---|---|
| Density | 7.85 g/cm³ | 8.00 g/cm³ |
| Tensile strength | 270–350 MPa | 515 MPa |
| Yield strength | 140–240 MPa | 205 MPa |
| Elongation | 28–38 % | 40 % |
| Minimum bend radius | 0.5 × thickness | ~1.0 × thickness |
| Relative cost | Very low | Medium |
Published values for standard grades at 23 °C unless stated, taken from each material's own datasheet page. Confirm against the supplier datasheet for the grade you specify.
What Mild steel (CRCA) is
CRCA is low-carbon steel cold rolled to a smooth, dimensionally accurate sheet, then annealed to restore ductility. It forms tightly, to as little as 0.5 times thickness inside radius, welds by MIG or spot without preheat or special procedure, and costs less than any structural sheet alternative. It has no corrosion resistance of its own: every CRCA part needs powder coating, plating, or galvanising, and that coating has to be specified and maintained for the life of the part, not applied once and forgotten.
What Stainless 304 is
304 is an austenitic chromium-nickel stainless and the most used stainless grade worldwide. The chromium forms a passive oxide film that reforms on its own if scratched, which is why a 304 part needs no coating to survive wet, washdown, or chemically mild service. It is very ductile, deep draws well, and welds without special procedure, but it work hardens aggressively under a cutting tool, which is why a 304 part costs materially more to machine than the same feature in mild steel, not just more to buy as raw stock.
Mild steel against Stainless 304
| Mild steel (CRCA) | Stainless 304 | |
|---|---|---|
| Weight | 7.85 g/cm³, nearly identical to stainless | 8.00 g/cm³, about 2 % denser, not a real differentiator between these two |
| Corrosion resistance | None. Bare CRCA rusts in ordinary humidity within days | Self-healing passive oxide film, no coating needed for most environments |
| Ongoing maintenance | The coating is a wear item: scratches, edge chips, and weld splatter all need touch-up over the part's life | Nothing to maintain against corrosion once passivated after fabrication |
| Formability | Tighter minimum bend radius, 0.5 × thickness, and smaller, more predictable springback | Wider minimum bend radius, roughly 1.0 × thickness, with significant springback that needs tool compensation |
| Machinability | Cuts and drills easily, no work hardening to manage | Work hardens under the cutting tool; the same feature takes longer and costs more to machine |
| Weldability | Welds without preheat or special procedure; grind and fill seams before coating if the surface is cosmetic | Welds readily; specify 304L on welded assemblies to avoid carbide precipitation at the heat-affected zone |
| Relative cost | Very low material cost, plus a coating line item that recurs at every touch-up | Medium material cost, higher machining cost, zero ongoing coating cost |
Which one, for which part
- Enclosures, brackets, and structural sheet parts that stay dry and get painted anyway favour mild steel: the coating is being applied for appearance or brand colour regardless, so stainless buys nothing extra.
- Food, beverage, pharmaceutical, or medical equipment, and any washdown or wet environment is 304's case: no coating to specify, apply, or maintain, and it holds up to cleaning chemicals a painted CRCA part would not survive.
- High-volume brackets and pressings on a tight machining and material budget favour mild steel: it is cheaper to buy, faster to cut and form, and does not work harden.
- A part that will be scratched, chipped, or abraded in service, machine guarding, handled fixtures, outdoor hardware, favours 304: a coating breach on CRCA is a rust start point, a scratch on 304 just exposes fresh passive metal.
- Coastal or high-humidity sites where a coating failure would be expensive to inspect and fix favour 304 despite the higher upfront cost, since the alternative is a maintenance programme, not a one-time spec decision.
Our status
Trumould machines and forms both mild steel (CRCA) and Stainless 304 in-house across CNC machining and sheet metal fabrication; neither runs through injection molding or 3D printing here. Send the part, its service environment, and target volume, and the quote states which of the two is recommended and why, not just a price for whichever one you asked about first.
Specifying this part?
Send your CAD and target volumes. We come back with a price, a lead time, and any material or design notes that would reduce either.