12L14 Steel
A free-machining steel with lead
Typical values for the temper in the title
12L14 is 1215 with added lead. Lead forms particles in the material that act as a lubricant during cutting, making it one of the fastest steels to machine.
It is very common on automatic lathes for small precision parts. The cost: low strength, no welding, and dangerous lead fumes when hot. Because of the lead, regulatory limits (for example RoHS) should be checked for some products.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 540 MPa | |
| Yield strength Rp0.2 | 415 MPa | |
| Elongation A | 10% | |
| Hardness | 163 HB | |
| Modulus of elasticity E | 200 GPa | |
| Density ρ | 7.83 g/cm³ | |
| Machinability | 170%! (Pb+S) | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| C carbon | max 0.15 | low |
| Mn manganese | 0.85–1.15 | forms MnS inclusions |
| S sulfur | 0.26–0.35 | chip breaker |
| P phosphorus | 0.04–0.09 | improves finish |
| Pb lead | 0.15–0.35 | an internal lubricant in cutting |
| Fe iron | balance |
Ranges per SAE J403 (Pb is reported as a 0.15–0.35 range). Equivalents in other standards are close in composition, not identical.
Conditions and heat treatment
Free-machining steels are chosen for machining, not for heat treatment.
| Condition | Properties | When to choose it |
|---|---|---|
| Cold drawn (CD) | strength and dimensional accuracy | bar for automatic lathes |
| Not intended for heat treatment | — | chosen for machining, not for strength |
Applications
- Automatic lathe parts
- Hydraulic and pneumatic fittings
- Connectors, screws and nuts
- Bushings and pins
- Small parts in large volumes
Fabrication
Machining
Very fast, with short chips and a good finish.
Welding
Not suitable: sulfur and lead cause cracking.
Hardening
Can be carburized for the surface, but not intended for highly loaded parts.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 1018 | 400 / 220 MPa | Excellent | more weldable and stronger, machines slower · material page |
| 1215 | 415 / 230 MPa | Poor | without lead · material page |
| 1144 | 703 / 586 MPa | Medium — S causes porosity | much stronger, and still machines well · material page |
Common mistakes
Welding 12L14
Sulfur and lead cause cracking. For a welded part, 1018.
Using 12L14 in a loaded part
Strength and toughness are low. For such a part, 1045 or 4140.
Ignoring the lead
For products under lead regulations, check in advance.
Equivalents, standards and supply
| EN | 11SMnPb37 (close) |
|---|---|
| JIS | SUM24L |
| Standards | ASTM A108 / SAE J403 |
| Forms | rod · profile |
| Producers | Nucor · TimkenSteel · Ovako |
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