6061-T6 vs 1018 Mild Steel
6061-T6 aluminum and 1018 mild steel are the two default "general-purpose" metals, so the real question is whether you're optimizing for weight and corrosion resistance or for raw strength, stiffness, and low cost.
The verdict
Choose 6061-T6 aluminum when weight, corrosion resistance, or anodizing matter — structural parts, enclosures, heat sinks, marine/outdoor hardware. Choose 1018 mild steel when you need maximum strength and stiffness per dollar, easy welding, case-hardening, or high-temperature service, and weight isn't a constraint. Aluminum wins on strength-to-weight and corrosion; steel wins on absolute strength, stiffness, and price.
Side-by-side data
| Property | 6061-T6 | 1018 Mild Steel |
|---|---|---|
| Category | Aluminum | Steel |
| Density (g/cm³) | 2.7 | 7.87 |
| Tensile strength (MPa) | 310 | 440 |
| Yield strength (MPa) | 276 | 370 |
| Elongation (%) | 12 | 15 |
| Hardness | 95 HB | 126 HB |
| Max service temp (°C) | 170 | 400 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 167 | 51 |
| Typically used for | All-round structural & machined parts — the default aluminum | General low-carbon parts, weldable |
Which should you choose?
Choose 6061-T6 Aluminum if…
- Weight is a design driver — aerospace, robotics, EV, drones, portable equipment, or anything that moves or accelerates.
- The part lives outdoors, in marine, or in humid environments and you want corrosion resistance without paint or plating.
- You want to anodize for a hard, decorative, or electrically isolating surface (steel can't be anodized).
- You're machining intricate parts fast — 6061 cuts easily and is gentle on tooling.
- You need good thermal/electrical conductivity, e.g. heat sinks or busbars.
Choose 1018 Mild Steel if…
- You need maximum strength, stiffness, and load capacity for the lowest material cost.
- The assembly will be welded — 1018 welds readily with no loss of base-metal strength and no heat-treat to restore.
- You plan to case-harden (carburize) for a wear-resistant surface over a tough core — gears, pins, shafts.
- Service temperatures are high; steel holds strength far better than aluminum above ~150-200°C.
- Stiffness/deflection governs the design — steel's much higher elastic modulus resists bending and flex.
Key differences that matter
- Strength-to-weight: steel is stronger in absolute terms, but aluminum is roughly a third the weight, so 6061-T6 usually wins on strength per unit mass — the reason it dominates weight-critical design.
- Stiffness: steel's elastic modulus is about 3x aluminum's, so for the same geometry a steel part deflects far less; aluminum parts often need thicker sections to match rigidity.
- Corrosion: 6061 forms a self-protecting oxide and survives outdoors bare; 1018 rusts readily and needs paint, oil, plating, or galvanizing.
- Weldability: 1018 welds easily and cheaply; welding 6061-T6 anneals the heat-affected zone and drops local strength unless you re-heat-treat.
- Cost & temperature: 1018 is cheaper per pound and per unit strength, and keeps its properties hot, while aluminum loses strength as temperature climbs.
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Open the Material SelectorGet a Quote →Frequently asked questions
Is 6061-T6 aluminum stronger than 1018 mild steel?
Not in absolute terms — 1018 has higher yield and tensile strength. But 6061-T6 has a better strength-to-weight ratio, so a same-weight aluminum part can outperform steel. For raw load capacity at a given size, steel wins; for the lightest part at a given strength, aluminum wins.
Which is cheaper, aluminum or mild steel?
1018 mild steel is cheaper per pound and offers more strength per dollar, making it the budget choice for heavy structural work. Aluminum costs more per pound, though faster machining and no need for paint/plating can narrow the gap on finished parts.
Can I weld both 6061-T6 and 1018?
Yes, but differently. 1018 welds easily with standard MIG/TIG/stick and keeps its strength. 6061-T6 is weldable (TIG/MIG with the right filler), but the weld zone is annealed and loses much of its T6 strength unless you re-solution-treat and age, which is rarely practical.
Can both metals be hardened or anodized?
1018 can't be through-hardened (low carbon) but case-hardens well via carburizing for a wear surface. 6061-T6 is already heat-treated and can't be case-hardened, but it anodizes excellently for a hard, corrosion-resistant, or colored finish. Steel cannot be anodized.
Which machines more easily?
6061-T6 machines faster with lower cutting forces, longer tool life, and good surface finish — a favorite for CNC. 1018 machines well for steel and is a common screw-stock grade, but it's slower, harder on tooling, and gummier, often needing coolant and chip control.
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.