S45C STEEL
S45C Steel Bars
A 0.45% carbon steel that machines cleanly, hardens well and costs less than alloy grades. We roll it in rounds, bright bars, hexagons, squares, flats and RCS.
A workhorse grade
S45C is a plain 0.45% carbon steel to JIS G4051. It's stronger than mild steel but still machines cleanly and takes heat treatment without any fuss, and it costs less than alloy grades like 4140 — which is why it shows up in so much everyday machinery. It forges well and hardens predictably, so you can normalize it, quench and temper it, or just harden the surface where the part wears.
Equivalent grades
Chemical composition
Per JIS G4051 (ladle analysis):
| Element | C | Si | Mn | P max | S max |
|---|---|---|---|---|---|
| wt % | 0.42–0.48 | 0.15–0.35 | 0.60–0.90 | 0.035 | 0.035 |
Mechanical properties
| Property | Normalized | Quenched & Tempered |
|---|---|---|
| Tensile strength | ≥ 570 MPa | ≥ 690 MPa |
| Yield strength | ≥ 345 MPa | ≥ 490 MPa |
| Elongation | ≥ 20% | ≥ 17% |
| Brinell hardness | 167–229 HB | 201–269 HB |
Indicative per JIS G4051; actual properties depend on section size and heat treatment, confirmed on the mill test certificate.
Heat treatment
| Process | Typical practice |
|---|---|
| Forging | 850 – 1,100 °C |
| Normalizing | 830 – 870 °C, air cool |
| Hardening | 820 – 860 °C, water/oil quench |
| Tempering | 550 – 660 °C, to required properties |
Heat
Raise to ~830–860 °C until structure transforms.
Quench
Cool fast in oil or water to lock in hardness.
Temper
Reheat gently to add back toughness.
S45C vs EN8D — what's the difference?
Very little — they're the same ~0.45% carbon steel under two standards: S45C is the Japanese (JIS G4051) name and EN8D the British one (BS 970, 080A42). Chemistry, strength and heat-treatment response are effectively identical, so on most drawings they're interchangeable.
The practical difference is finish and condition: EN8D is usually supplied as cold-drawn bright bar — close tolerance and a clean surface, ready to use — while S45C is commonly hot-rolled black bar to machine or forge from oversize. Need the bright version? See EN8D steel.
Sizes & forms we supply
We manufacture S45C in these standard forms and sizes. Standard mill lengths are 5–6 m, or we cut to your requirement — see our full size range:
| Form | Size range |
|---|---|
| Rounds | 23.5 mm – 80 mm |
| Bright bars (cold drawn) | 22 mm – 63.5 mm |
| RCS (round-cornered square) | 55 mm, 63 mm, 75 mm |
| Hexagons | 23.5 mm – 52.5 mm |
Finish, certification & ordering
Finishes
Hot rolled (black bar), cold-drawn bright bar, and annealed for easy machining.
Testing & certificate
A heat-wise mill test certificate — chemistry and mechanicals against the heat number — with every consignment. Ultrasonic testing, micro/macro and decarburisation checks on request.
Ordering & packing
From about 3 MT per size, several forms in one order, cut to length. Bars are strapped and end-tagged with grade and heat number, packed for road or container export.
Related grades & guides
Machinability, weldability & formability
Machinability
Excellent finish in normalized or hot-rolled condition.
Weldability
Preheat & stress-relieve thicker sections.
Formability
Cold form when annealed; excellent hot.
Applications
Frequently asked questions
What is S45C steel?
What is S45C steel equivalent to?
Is S45C the same as EN8?
What is the hardness of S45C steel?
Can S45C steel be hardened?
Is S45C steel weldable?
What is S45C steel used for?
Manufacturer, not a trader
In-house mill
Quality controlled end to end.
Certified
MTC + traceable heats every dispatch.
All forms
Round, bright, hex, flat, RCS in one order.
Export ready
Regular packing for global supply.
Need S45C to spec?
Send us your sizes and quantities and we'll get back with a price.