SteelKey facts
- Carbon steel is sorted into low, medium, high and ultra-high carbon classes by carbon content, and high carbon wire comes from the third class.
- As carbon content rises, steel can become harder and stronger, but it becomes less ductile.
- Wikipedia names springs, edged tools and high-strength wires as uses of high-carbon steel.
- A higher carbon content also reduces weldability, whatever the heat treatment.
- Reinwent’s spring steel wire, the high carbon product, runs from 1.3 to 4 mm, with standards on request.
The short answer
Every steel wire contains carbon. What makes a wire high carbon is how much: the carbon content places the steel in a class, and the high class sits above low and medium. The extra carbon adds strength and takes ductility away, so high carbon wire is found where strength and spring-back matter more than easy bending.
This page is the material-level explainer. Spring construction and standards are in what spring wire is and spring wire standards. Here we look at the carbon.
What makes steel wire high carbon?
Wikipedia sorts carbon steel into classes by carbon content: low-carbon, medium-carbon, high-carbon and ultra-high-carbon. Wire is high carbon when the steel it was drawn from falls in the high class.
We quote no percentage here. Wikipedia gives a range for each class, but its own sections do not agree on the limits of the low class, and no second source we read sets limits for wire. Write the carbon requirement as your standard words it, and have the manufacturer confirm it in the quotation.
Wikipedia describes spring steel as typically medium-carbon or high-carbon steel with a very high yield strength. Many spring wires are therefore high carbon wires, but the names differ: high carbon describes the material, spring wire a job.
What carbon does to strength, hardness and ductility
Strength and hardness. Wikipedia states that as the carbon content percentage rises, steel has the ability to become harder and stronger through heat treating. Its article on steel adds that the strengthening is primarily due to the introduction of carbon into the iron lattice, and that carbon-rich phases are hard.
Ductility. The same gain has a cost. Wikipedia says that as carbon rises, steel becomes less ductile, and that steel gives up elongation as carbon is added. High carbon wire forgives less when bent sharply.
Weldability. Wikipedia says that regardless of the heat treatment, a higher carbon content reduces weldability. If a part is to be welded after forming, say so when you enquire.
None of the sources we read gives a bend, elongation or tensile figure for high carbon wire as a class, so we give none. The only strength figures here come from our product pages.
Carbon is not the only thing that sets strength
Carbon sets what the steel can reach. The wire’s route decides where it ends up.
Drawing is the first factor: IspatGuru notes that drawn steel is strengthened. See the wire drawing process and what cold drawn wire is.
Heat treatment is the second. Wikipedia says annealing increases ductility and reduces hardness. Our spring steel wire page adds that some spring wires are heat treated by patenting or alloyed with silicon and chromium, and the BSI entry for EN 10270-1 puts patented in the standard’s title. We found no fetched source that explains patenting step by step, so we do not.
Two coils from one carbon class can differ in strength, so a carbon class alone is a poor specification. For spring wire, see oil tempered vs hard drawn spring wire.
Where high carbon wire is used
Wikipedia’s Carbon steel article says high-carbon steels are very strong and are used for products such as springs, edged tools and high-strength wires. Our own page for spring steel wire names three jobs:
- Coil springs. Wire wound around a former into compression, extension or torsion springs.
- Vehicle springs. Suspension springs are the example on the product page.
- Formed parts. Parts that must return to shape after bending.
The common thread is elastic recovery: Wikipedia says spring steel lets objects return to their original shape despite significant deflection or twisting. Our range for these jobs runs from 1.3 to 4 mm in diameter.
High carbon wire compared with the soft wires
The table uses only our product page values.
| Feature | Spring steel wire | Cold drawn wire | Black annealed wire | Galvanized wire |
|---|---|---|---|---|
| Diameter | 1.3 to 4 mm | 0.8 to 6 mm | 0.8 to 8 mm | 0.8 to 8 mm |
| Tensile strength | On request | 500 to 1,000 N/mm² | 300 to 450 N/mm² | Not listed |
| Standard | On request | EN 10218-2 | EN 10218-2 | EN 10244-2, ASTM A641 |
| Coating | Agreed per order | None, bright | None, black | 50 to 300 g/m² |
| Feel in the hand | Springs back | Stiff | Soft, ties easily | Depends on temper |
| Typical use | Springs, formed parts | Nails, staples, bolts | Binding, tying | Outdoor and damp use |
Black annealed wire is the clearest contrast. It is soft because annealing took the hardness out, not because of a carbon figure we can quote. The product page gives no carbon class for it, and neither does any source we read, so we do not label it low carbon. Its band of 300 to 450 N/mm² sits below cold drawn wire. See black annealed wire uses.
For the hard against soft comparison in detail, read hard drawn vs annealed wire. For how strength is tested and written, read what high tensile wire means. Galvanized wire follows ASTM A641, which covers zinc-coated carbon steel wire in soft, medium and hard temper, so a coated wire can also be bought soft or hard. For the whole map, see types of steel wire.
What to specify when you buy
Carbon class alone leaves the wire open, so write the following.
- Diameter in millimetres. Our spring steel wire runs from 1.3 to 4 mm. If a drawing uses a gauge number, convert it with the wire gauge chart.
- Tensile band. Give a minimum and maximum in N/mm² where strength matters. Our spring product lists no band, so it is agreed per order.
- Standard. Name the one your spring drawing or customer calls for. EN 10270-1 and ASTM A227 are the two widely named for spring wire, and the grade or class goes with it.
- Duty. State whether the finished part works under a static or a dynamic load, as the spring standards do.
- Surface. Bare, or coated if the part will meet weather.
- Coil weight. Give the coil weight your line takes. How coils travel is in the container loading guide.
- Quantity and port.
High carbon wire from manufacturers in Türkiye
Reinwent is a trading and sourcing company, not a manufacturer. We do not draw or heat treat wire. We source steel wire from manufacturers in Türkiye, collect their offers and put them on one basis, so you compare like with like. Our spring steel wire page gives the range, and spring steel wire from Türkiye describes the supply route. Standards are on request and confirmed in the quotation.
A quotation reaches you within 12 hours at the latest, and we stay in contact until delivery. Some products are available from stock. When your diameter, tensile band, standard and coil weight are settled, request a quote.
