Medium and High-Carbon Steel
Medium-carbon steel (0.30–0.60 % C: 1035, 1045, 1050) has enough carbon to quench-harden — 1045 reaches about 55 HRC at the surface — and is used normalized or quench-and-tempered for shafts, keys and machine parts at 300–600 MPa yield. High-carbon steel (0.60–1.0 % C: 1074, 1084, 1090) hardens to 60–65 HRC and is the plain steel for blades, flat springs and hand tools. Neither contains alloy, so hardening is shallow and weldability drops as the carbon rises.
Popular medium and high-carbon steel grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| 1045 | 530 | 625 | 7.85 | Fair | Fair | General-purpose hardenable shafts and keys |
| 1040 | 415 | 620 | 7.85 | Good | Fair | Forged levers and studs; a little more weldable |
| 1050 | 340 | 620 | 7.85 | Fair | Poor | Keys, sprockets, hand-tool bodies |
| 1060 | 370 | 675 | 7.85 | Fair | Poor | Machetes, axle shafts, rail components |
| 1074 | 380 | 655 | 7.85 | Fair | Poor | Flat springs and clips; hardens evenly |
| 1084 | 585 | 965 | 7.85 | Fair | Poor | Knife blades and punches; easy to harden |
| 1541 | 415 | 700 | 7.85 | Good | Fair | Larger bolts and axles; Mn for hardenability |
Choose medium and high-carbon steel for
Shafts, axles, keys, pins and sprockets that need a hardened wear surface without the cost of alloy steel; knives, chisels, flat springs, clips and hand tools where a plain steel that hardens to 60 HRC is enough; forgings and induction-hardened parts.
Look elsewhere when
The section is over about 25 mm and must harden through (4140, 42CrMo4), toughness at high hardness matters (4340 or S7), the part carries a lot of welding or is welded after hardening (1018, 1020), a coil spring needs fatigue life (5160, 9254, 6150), or a blade must hold a fine edge and resist wear (O1, D2).
Loading the library…
Medium and high-carbon steel by application
- Shafts with hardened journals
- 1045 induction-hardened to 55–58 HRC on the bearing surfaces with the core left at 20–25 HRC; the drawing should call out the hardened zone and case depth (typically 1.5–3 mm). S45C and 45# are the same grade on JIS and GB drawings.
- Keys, pins and sprockets
- 1045 or 1050 through-hardened and tempered to 40–45 HRC in sections under 20 mm; 1060 when a harder wear face is needed. 1541 for bolts and studs above about 25 mm where 1045 will not harden deep enough.
Working with medium and high-carbon steel
- Machining
- Machines better than mild steel — the higher carbon breaks the chip and gives a cleaner finish. 1045 is cut normalized or hot-rolled at about 80 % of the speed used for 1018; above 0.60 % C (1074–1090) use annealed stock and slow down. Rough before hardening and leave 0.1–0.3 mm for grinding — plain carbon steel distorts more in a water quench than alloy steel does in oil.
- Welding
- 1035–1045 weld with 150–250 °C preheat, low-hydrogen filler (E7018) and a slow cool; above 0.50 % C cracking in the heat-affected zone is likely and welding is repair-only. Weld first, then heat-treat — welding a hardened 1045 shaft leaves an untempered martensite band that fails in service.
- Heat treatment
- Water or fast-oil quench from 815–870 °C; hardenability is shallow, so a 25 mm 1045 bar is about 55 HRC at the surface and 30 HRC at the center. Flame and induction hardening are where these grades shine: a local hard case with no alloy premium. Temper 1084 / 1090 blades at 175–230 °C for 58–62 HRC; temper 1045 at 400–550 °C for a tough 28–35 HRC.
- Finishing
- Black oxide, phosphate and oil, zinc plating and hard chrome all work; blades are usually left bright and oiled. Grind hardened surfaces with plenty of coolant — a 1090 edge at 62 HRC burns and softens easily.
Other steel series
- Low-Carbon and Mild Steel
- Free-Machining Steel
- Alloy Steel
- Case-Hardening Steel
- Tool Steel
- Mold Steel
- Spring and Bearing Steel
- Structural and HSLA Steel
- Wear Plate and Advanced High-Strength Steel
- Pressure Vessel and Chromium-Molybdenum Steel
- Electrical Steel and Soft Magnetic Alloys
- Aerospace and Maraging Steel
- Cast Steel
- Cast Iron
- Steel Welding Consumables
Medium and High-Carbon Steel — frequently asked
What is medium and high-carbon steel?
Medium-carbon steel (0.30–0.60 % C: 1035, 1045, 1050) has enough carbon to quench-harden — 1045 reaches about 55 HRC at the surface — and is used normalized or quench-and-tempered for shafts, keys and machine parts at 300–600 MPa yield. High-carbon steel (0.60–1.0 % C: 1074, 1084, 1090) hardens to 60–65 HRC and is the plain steel for blades, flat springs and hand tools. Neither contains alloy, so hardening is shallow and weldability drops as the carbon rises.
Which grade of medium and high-carbon steel should I use?
1045 (S45C, 45#) is the general-purpose hardenable bar: machinable, flame- or induction-hardened to 55 HRC on wear surfaces, or quench-and-tempered to 25–30 HRC through thin sections. 1040 and 1035 are slightly softer and more weldable for forged levers and studs; 1050 and 1060 give more hardness for keys, sprockets and hand-tool bodies. 1541 adds manganese for better hardenability in larger bolts and axles. For blades and springs go to 1074 and 1084 (near-eutectoid, forgiving to heat-treat) or 1090 for maximum hardness at the edge; 1095 in the spring and bearing group is the same idea with a little more carbon.
Which grade of medium and high-carbon steel is the strongest?
C60E has the highest yield strength in the series at 620 MPa; 1084 follows at 585 MPa. Values are for each grade's default condition.
Which grade of medium and high-carbon steel is easiest to machine?
1038 (machinability good, 63/100), then 1042 (62/100).
Is medium and high-carbon steel heat-treatable?
Yes. These grades gain their strength from heat treatment; the conditions and their properties are listed on each grade page.
1045 or 4140 for a shaft?
If the shaft is under about 25 mm or only needs a hardened surface, 1045 does it at lower cost: induction-harden the journals and leave the core soft. Above that, or when the whole section must be 28–32 HRC with good toughness, 4140 — the chromium and molybdenum let it harden through in oil with less distortion, and it tempers to a wider range of properties. 4140 also machines cleaner in the pre-hardened condition.
What is the difference between 1084 and 1095 for a knife?
1084 is near-eutectoid (0.80–0.93 % C), so it hardens fully with a simple 800 °C austenitize and fast oil quench with no retained-carbide problems — a forgiving blade steel to heat-treat. 1095 (0.90–1.03 % C) reaches a point or two more hardness and holds an edge slightly longer but needs a faster quench and a short soak to avoid soft spots. Both temper to 58–62 HRC and rust just as readily.