1018 Mild Steel vs 304 Stainless
1018 mild steel and 304 stainless are both workhorse steels, but the choice hinges on one question: does the part need to survive corrosion on its own, or can you trade that for lower cost and easier fabrication?
The verdict
Choose 1018 Mild Steel when cost, machinability, and weldability matter and the part is painted, plated, oiled, or used indoors. Choose 304 Stainless when the part faces moisture, food, chemicals, weather, or heat and must resist corrosion with no coating. In short: 1018 for cheap, easy-to-fab structural and machined parts; 304 when bare-metal corrosion resistance is non-negotiable.
Side-by-side data
| Property | 1018 Mild Steel | 304 Stainless |
|---|---|---|
| Category | Steel | Stainless Steel |
| Density (g/cm³) | 7.87 | 8.0 |
| Tensile strength (MPa) | 440 | 515 |
| Yield strength (MPa) | 370 | 215 |
| Elongation (%) | 15 | 40 |
| Hardness | 126 HB | 201 HB |
| Max service temp (°C) | 400 | 870 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 51 | 16 |
| Typically used for | General low-carbon parts, weldable | General corrosion-resistant parts |
Which should you choose?
Choose 1018 Mild Steel if…
- The part lives indoors, dry, or will be painted, powder-coated, plated, or oiled to handle corrosion
- Cost is a primary driver and you want the cheapest readily-available bar stock
- You're machining, drilling, tapping, or welding in volume and want predictable, easy fabrication
- You need a steel that case-hardens or carburizes well for wear surfaces (shafts, pins, gears)
- Magnetic response is acceptable or desired (jigs, fixtures, magnetic clamping)
Choose 304 Stainless if…
- The part sees moisture, humidity, weather, washdown, or splash and must not rust without a coating
- It contacts food, beverages, water, or mild chemicals where hygiene and corrosion resistance are required
- You need an attractive, maintainable bare-metal finish (railings, enclosures, hardware) with no painting
- The application runs hot and must keep strength and oxidation resistance at elevated temperatures
- You want a non-magnetic part in the annealed condition and want to avoid coating maintenance over its life
Key differences that matter
- Corrosion is the deciding factor: 1018 rusts readily and needs a coating or oil; 304's chromium oxide layer self-heals and resists rust, food acids, and many chemicals bare.
- Machinability favors 1018: it cuts cleanly and predictably, while 304 work-hardens, gums up, and demands sharp tooling, slower speeds, and more rigid setups.
- Strength is comparable, but stiffness is identical: both share roughly the same elastic modulus, so 304 buys corrosion resistance, not a lighter or stiffer part.
- Weldability differs in kind: 1018 welds easily with common methods; 304 welds well too but risks sensitization and warping, often needing low heat input or proper filler.
- Temperature and hygiene: 304 holds strength and resists scaling when hot and is food/medical safe; 1018 loses strength and oxidizes, and is unsuitable for bare food contact.
Need 1018 Mild Steel or 304 Stainless parts made?
Use our free tools to finalize your spec, then get a quote from a vetted factory.
Open the Material SelectorGet a Quote →Frequently asked questions
Is 1018 mild steel stronger than 304 stainless?
They're in the same ballpark and it depends on condition. Cold-drawn 1018 and annealed 304 have similar yield and tensile strength. Neither is dramatically stronger; the real differences are corrosion resistance and fabrication behavior, not raw strength. For high strength you'd step up to an alloy or hardened grade rather than choosing between these two.
Which is cheaper, 1018 or 304?
1018 is significantly cheaper, both in raw material and to machine. 304's nickel and chromium content drives up cost, and its work-hardening makes it slower and harder on tooling. But factor in lifecycle cost: if 1018 needs plating, painting, or periodic re-coating to survive its environment, 304's higher upfront price can pay off.
Can I weld both 1018 and 304?
Yes. 1018 welds easily with MIG, TIG, or stick using common filler. 304 also welds well, typically with TIG and a matching filler like 308L, but it's prone to warping from its higher thermal expansion and to sensitization (chromium carbide formation) if held too long in the critical temperature range, which can hurt corrosion resistance near the weld.
Does 304 stainless ever rust?
It resists rust far better than 1018 but isn't immune. In chloride-rich settings (salt, seawater, pool chemicals) 304 can pit or suffer crevice corrosion; 316 is the upgrade there. Surface contamination from carbon-steel tooling or particles can also cause cosmetic 'tea staining.' For most freshwater, indoor, and food uses, 304 stays clean indefinitely.
Is 304 stainless magnetic?
In the annealed condition 304 is essentially non-magnetic, which matters for some sensors and electronics. However, cold working (bending, machining, forming) can induce partial magnetism. 1018 is fully ferromagnetic, which is an advantage for magnetic fixturing and clamping but a drawback where magnetic interference must be avoided.
Property values are typical/nominal figures for early-stage guidance only and vary by temper, grade, supplier and heat treatment. Confirm critical specifications against a certified datasheet or with an mfgiq engineer before production.