Steel C45 · heat-treated state
Steel C45 +AC
Properties of the +AC condition, compared with the other C45 tempers.
Spheroidize-annealed C45/1.1061 bar with globular carbides — lowest hardness and best cold-heading/cold-extrusion ductility of the non-hardened conditions.
What is C45 +AC?
C45 +AC is C45 heat treated to +AC — spheroidize-annealed C45/1.1061 bar with globular carbides — lowest hardness and best cold-heading/cold-extrusion ductility of the non-hardened conditions. C45 +AC has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 78% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi). C45 +AC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). Normalized is the default condition FabDigit quotes; +AC is available on request or by drawing note.
Advantages
- High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Low strength — 330 MPa (47.9 ksi), worse than 78% of steel grades
C45 +AC properties
Typical room-temperature values for C45 +AC — 40 properties are specific to this condition; the rest are grade-level values shared by every C45 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
C45 +AC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
C45 +AC has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 78% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
C45 +AC is rated for continuous service to 400°C (752 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
C45 +AC conducts electricity at 10.8 % IACS, better than 94% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of C45 +AC takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
C45 +AC's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (45/100); formability good (65/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other C45 tempers and conditions
C45 is also supplied in 9 other conditions. The full side-by-side table is on the C45 overview.
- NormalizedDefaultStandard stock condition for shafts and machined parts needing uniform medium strength and predictable machining.400 MPa yield · 190 HB
- Q&T 28-32 HRCSpecify when a hardness-controlled, higher-strength core is required for gears, couplings and hydraulic parts.760 MPa yield · 30 HRC
- Q&T 22-26 HRCUse where toughness and weld-repairability matter more than peak strength (large shafts, pressure parts).620 MPa yield · 24 HRC
- +CPick for close-tolerance bright bar used as-is for shafts, pins and turned parts.580 MPa yield · 210 HB
- +AC+CSpheroidized then cold-drawn C45/1.1061 bright bar — close tolerances and smooth surface with strength raised by drawing while retaining useful cold-forming ductility.500 MPa yield · 195 HB
- +QTStandard delivery condition for loaded shafts, gears and fasteners needing higher yield with retained toughness.480 MPa yield · 20 HRC
- IHBest choice for wear surfaces — journals, guide rails, splines — keeping a tough normalized or Q&T core.450 MPa yield · 57 HRC
- +AChoose for maximum machinability, cold forming or before final hardening.350 MPa yield · 165 HB
- +ACSpheroidize-annealed C45/1.1061 bar with globular carbides — lowest hardness and best cold-heading/cold-extrusion ductility of the non-hardened conditions.330 MPa yield · 175 HB
- HRCheapest stock form for weldments and rough-machined parts where strength scatter is acceptable.330 MPa yield · 175 HB
Working with C45 +AC
Is C45 easy to machine?
Machines well in +N or +A at ~57% of 1212; use carbide at 120–200 m/min, expect stringy chips and moderate tool wear above 28 HRC.
Can C45 be welded?
Weldable but crack-sensitive (CE≈0.55): preheat 150–250 °C, low-hydrogen consumables, and post-weld stress relief or re-normalizing.
Can C45 be formed, bent or molded?
Hot forge at 1100–850 °C then normalize; cold bending only in annealed condition with generous radii (≥3t).
What surface finishes work on C45?
No anodizing — protect by oxide blackening, zinc phosphate, zinc/Cr plating, nitriding or paint; polishes to a good bright finish for mould plates.
C45 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CEN 10083-2 C45 | 0.42 – 0.5 | 0.45 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.5 – 0.8 | 0.65 |
| P | ≤ 0.03 | — |
| S | ≤ 0.04 | — |
| CrCr+Mo+Ni ≤ 0.63 | ≤ 0.4 | — |
| Ni | ≤ 0.4 | — |
| Mo | ≤ 0.1 | — |
| Fe | balance | — |
C45 +AC — frequently asked
What is C45 +AC used for?
C45 +AC is typically used for crankshafts, shafts and industrial bolts. In short: european medium-carbon bar.
What is the yield strength of C45 +AC?
C45 +AC has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 78% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is C45 +AC easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines well in +N or +A at ~57% of 1212; use carbide at 120–200 m/min, expect stringy chips and moderate tool wear above 28 HRC.
Can C45 +AC be welded?
With care — weldability is rated fair (45/100). Weldable but crack-sensitive (CE≈0.55): preheat 150–250 °C, low-hydrogen consumables, and post-weld stress relief or re-normalizing.
What surface finishes work on C45 +AC?
No anodizing — protect by oxide blackening, zinc phosphate, zinc/Cr plating, nitriding or paint; polishes to a good bright finish for mould plates.
Can C45 +AC be formed, bent or molded?
Hot forge at 1100–850 °C then normalize; cold bending only in annealed condition with generous radii (≥3t).
What is the maximum service temperature of C45 +AC?
C45 +AC is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between C45 Normalized and C45-HR?
Normalized is the default condition — standard stock condition for shafts and machined parts needing uniform medium strength and predictable machining. HR: cheapest stock form for weldments and rough-machined parts where strength scatter is acceptable. Yield strength is 400 MPa in Normalized versus 330 MPa in HR.
Can FabDigit make parts in C45 +AC?
Yes — C45 +AC is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10083-2 Steels for quenching and tempering — Non-alloy steels — CEN (2006)
- ASTM A29/A29M & SAE J403 (1045) — ASTM / SAE (2020)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 Fatigue and Fracture — ASM International (1996)
- C45 / 1.0503 bar datasheet — Saarstahl / Ovako (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.