1018 Steel
A low-carbon steel
Typical values for the temper in the title
1018 is the most common steel for cold-drawn bar. It has about 0.18% carbon and relatively high manganese (0.60–0.90%), so it is slightly stronger than 1020 and machines well.
It welds excellently, is suitable for carburizing, and is used for light shafts, pins, machine parts and lathe-turned parts. Cold drawn, its tensile strength is higher than hot rolled.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 400 MPa | |
| Yield strength Rp0.2 | 220 MPa | |
| Elongation A | 25% | |
| Hardness | 126 HB | |
| Modulus of elasticity E | 200 GPa | |
| Density ρ | 7.87 g/cm³ | |
| Machinability | 78% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| C carbon | 0.15–0.20 | sets strength and hardenability |
| Mn manganese | 0.60–0.90 | strength and hardenability |
| P phosphorus | max 0.040 | |
| S sulfur | max 0.050 | |
| Fe iron | balance |
Ranges per SAE J403 and ASTM A29. P max 0.040, S max 0.050 (except free-machining grades). Equivalents in other standards are close in composition, not identical.
Conditions and heat treatment
The properties of carbon steel depend strongly on the condition and heat treatment. The values at the top of the page are for the typical condition.
| Condition | Properties | When to choose it |
|---|---|---|
| Hot rolled (HR) | lower strength, scaled surface | simple parts, welding |
| Cold drawn (CD) | higher strength and dimensional accuracy | bar for machining |
| Carburized | hard surface, soft and tough core | light gears, pins and shafts |
Applications
- Light shafts and pins
- General machine parts
- Carburized parts
- Welded parts
- Bolts and fittings
Fabrication
Welding
Welds excellently by all methods, without preheat.
Machining
Good, especially cold drawn. Hot rolled tends to be gummy.
Heat treatment
Not through-hardenable, because it has little carbon. For a hard surface, carburize.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 1020 | 395 / 205 MPa | Excellent | less manganese, slightly softer · material page |
| 1045 | 570–700 / 310–450 MPa | Medium | medium carbon, hardenable · material page |
| 12L14 | 540 / 415 MPa | Poor — Pb causes Hot Crack | machines much faster, but does not weld · material page |
Common mistakes
Trying to through-harden 1018
It has too little carbon. For a hard surface, carburize.
Choosing 1018 for a highly loaded part
Strength is low. For a loaded part, 1045 or 4140.
Leaving it unprotected
Carbon steel rusts. Paint, plating or oil are needed.
Equivalents, standards and supply
| EN | C15 (close) |
|---|---|
| Standards | ASTM A108 / SAE J403 |
| Forms | wire · rod · plate · pipe |
| Producers | Nucor · CMC Steel · SSAB |
Learn more
Values are typical and for comparison only, and depend strongly on condition and diameter. For design, rely on the standard and on the mill certificate. Sources: SAE J403 and J404, ASTM A29, A322 and A519 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026