SteelWhat is 12L14 steel and what is it used for? Free-machining steel
12L14 steel is the free-machining steel par excellence: it is made to machine fast and with a good finish. In this guide we explain what 12L14 steel is, its composition, its properties, what it is used for and the sizes we stock.
What is 12L14 steel?
Resulfurized, rephosphorized and leaded low-carbon steel, developed to offer very high machinability. Its ferritic microstructure with manganese sulfide and lead inclusions promotes short chips and reduces tool wear. Supplied cold drawn, with good dimensional accuracy and moderate mechanical properties.
Chemical composition of 12L14 steel
This is the typical composition of 12L14 steel (AISI 12L14 / ASTM A108 / EN-DIN 1.0737 / JIS SUM24L standard):
| Element | Contents | What for? |
|---|---|---|
| Carbon (C) | 0.15 % max. | Low, for maximum machinability |
| Manganese (Mn) | 0.85 – 1.15 % | Hardenability; forms sulfides that aid cutting |
| Phosphorus (P) | 0.04 – 0.09 % | Rephosphorized: improves finish and cutting |
| Sulfur (S) | 0.26 – 0.35 % | Resulfurized: forms short chips (better machinability) |
| Lead (Pb) | 0.15 – 0.35 % | Leaded: lubricates the cut and raises machinability |
12L14 properties
12L14 is not about mechanical strength but machinability. It is one of the easiest-machining steels there is: sulfur, phosphorus and lead make the chip break short and the tool last longer, allowing high cutting speeds and a good finish. It is supplied cold drawn, with good dimensional accuracy. Its hardness is around 160 HB. It is not recommended for heavily loaded parts or for welding.
What is it for? Applications of 12L14
12L14 steel is mainly used in:
- Precision screws and bolts
- Machined nuts and connectors
- Bushings and sleeves
- Pins and dowels
- Couplings and threaded fittings
- CNC lathe parts
- Valve components
- Machined metal inserts
- High-production hardware
Forms and sizes we carry
At NAT MAC we stock 12L14 steel in these forms and sizes:
| Package size | Sizes |
|---|---|
| Round bars | Ø 1/4" – 3-3/4" (Ø 6 – 95 mm) |
| Hex bars | 5/16" – 3" (8 – 76 mm) |
If you need a particular size, tell us which one and we will gladly source it for you.
12L14 equivalents and standards
12L14 steel is also identified by these standards: AISI 12L14 / ASTM A108 / EN-DIN 1.0737 / JIS SUM24L You can see how to read them in our article on steel standards.
In summary
- 12L14 is a resulfurized, rephosphorized, leaded low-carbon steel with very high machinability
- Typical composition: C 0.15 max., Mn 0.85 – 1.15, with S and Pb for machining
- Supplied cold drawn; hardness ~160 HB; not for high strength or welding
- Ideal for high-volume machined parts: fasteners, connectors, bushings and pins
- We carry it in round bars, hex bars, cut to size
Why buy 12L14 steel at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry a wide range of carbon steels and help you choose the right one for your part.
- Quality 12L14 Steel, backed and traceable
- Material cut to the size you need
- Technical advice on choosing the right grade
- Wide range of carbon steels in stock
- On-time deliveries and competitive prices
Tell us what you are going to make and in what dimensions, and we will recommend the right material and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public industry references for hardness. Values are for reference and may vary by standard, heat and treatment.
