The standard quench-and-temper grade for small-to-medium load-bearing parts — C 0.42–0.50%, Mn 0.50–0.80%, EN 10083-2. After quenching and tempering: tensile 600–800 MPa, yield ≥350 MPa. Supplied spheroidized for blanking or Q&T to your hardness band.
C45E is the reference point for medium-carbon steel. It hardens by quenching and tempers to a useful strength-toughness balance in sections up to roughly 20–30 mm. Above that, alloy grades like 42CrMo take over.
SAE1020 (0.18–0.23% C) welds without preheat but cannot through-harden — it tops out around 500 MPa tensile in the cold-worked state. C45E (0.42–0.50% C) reaches 600–800 MPa after Q&T and takes a hard edge, but requires preheat if welding is attempted. Choose C45E when the part carries loads or needs hardness; SAE1020 when weldability is the priority.
C45E for strength/hardness; 1020 for weldability.42CrMo (EN 42CrMo4) adds Cr and Mo for deep hardenability — through-hardens in sections up to 100 mm+ and reaches 800–1,100 MPa tensile. C45E is limited to ~20–30 mm in water and delivers 600–800 MPa. C45E costs less per tonne and is the right call for small shafts, gears and bolts where 600–800 MPa is sufficient. See our alloy structural steel family for the 42CrMo grade.
C45E for small sections, lean cost; 42CrMo for large sections, high strength.SAE1078 (0.72–0.85% C) is a spring and blade grade that hardens to 55–60 HRC but is brittle in the as-quenched state. C45E tempers to a balanced 600–800 MPa with elongation typically 12–18% — it is tough enough for shafts and gears that see shock loads. Choose SAE1078 for springs and cutting edges; C45E for structural load-bearing parts.
C45E for tough structural parts; 1078 for springs and edges.The "E" suffix denotes controlled sulfur (≤0.030%) for consistent machinability and mechanical properties. Actual heat chemistry confirmed on MTC.
| Element | C45E (EN 10083-2) % | Notes |
|---|---|---|
| Carbon (C) | 0.42 – 0.50 | Primary hardening element; controls peak hardness and strength after Q&T |
| Manganese (Mn) | 0.50 – 0.80 | Deoxidizer; contributes to hardenability and solid-solution strengthening |
| Silicon (Si) | ≤ 0.40 | Deoxidizer; mild strengthening contribution |
| Phosphorus (P) | ≤ 0.030 | Residual; controlled for toughness and fatigue resistance |
| Sulfur (S) | ≤ 0.030 | Controlled (E grade); improves machinability while maintaining transverse toughness |
| Chromium (Cr) | ≤ 0.40 | Residual; not intentionally added in plain C45E |
| Molybdenum (Mo) | ≤ 0.10 | Residual |
| Nickel (Ni) | ≤ 0.40 | Residual |
Reference: EN 10083-2 — Steels for quenching and tempering. Values typical per standard, actual confirmed on MTC. Carbon equivalent (CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15) typically 0.55–0.65%, indicating limited weldability. Read our guide to reading the MTC for what each value means.
C45E is supplied either spheroidized (for blanking and forming, with the customer performing Q&T) or quenched and tempered to a specified property band.
| Condition | Tensile (typ.) | Yield (typ.) | Elongation (typ.) | Hardness (typ.) | Typical use |
|---|---|---|---|---|---|
| Spheroidized (soft annealed) | 550 – 700 MPa | 320 – 420 MPa | 15 – 22% | ≤ 207 HB | Blanking, forming, machining — part is Q&T afterwards |
| Q&T (500–650°C temper) | 600 – 800 MPa | ≥ 350 MPa | 12 – 18% | 180 – 240 HB | Shafts, gears, bolts, connecting rods — standard structural Q&T |
| Q&T (200–300°C temper) | 900 – 1,100 MPa | 700 – 900 MPa | 6 – 10% | 45 – 52 HRC | Wear parts, hand tools, cutting edges — hardness prioritized over toughness |
Values typical per EN 10083-2 and standard heat treat practice; actual confirmed on MTC. Through-hardening is limited to sections of approximately 20–30 mm in water quenching; thicker sections will have a softer core. For deep-hardening requirements, consider 42CrMo alloy steel.
C45E is the European designation. The same material family is known by different names in American, Chinese and Japanese standards — chemistry ranges overlap but are not identical.
| Standard | Grade | C (%) | Mn (%) | S (%) | Notes |
|---|---|---|---|---|---|
| EN 10083-2 (Europe) | C45E (1.1191) | 0.42 – 0.50 | 0.50 – 0.80 | ≤ 0.030 | Base reference; controlled sulfur |
| GB/T 699 (China) | 45# | 0.42 – 0.50 | 0.50 – 0.80 | ≤ 0.035 | Closest Chinese equivalent; widely used in Chinese machinery |
| ASTM A29 (USA) | AISI 1045 | 0.43 – 0.50 | 0.60 – 0.90 | ≤ 0.050 | Higher Mn and S; broadly equivalent for Q&T use |
| JIS G4051 (Japan) | S45C | 0.42 – 0.48 | 0.60 – 0.90 | ≤ 0.030 | Tighter C range; Japanese machinery standard |
| EN 10083-2 (Europe) | C45 (1.0503) | 0.42 – 0.50 | 0.50 – 0.80 | ≤ 0.060 | Higher sulfur for free machining; less tough than C45E |
Equivalents are approximate. Chemistry ranges and residual limits differ between standards. For regulated or safety-critical parts, confirm full chemistry against your governing specification and the MTC of the delivered heat.
1.0–4.0 mm C45E strip, blanked or fine-blanked into shaft blanks, then turned or ground to final diameter and quenched-and-tempered to 600–800 MPa. Typical parts: transmission shafts, motor shafts, pump shafts, small axles and spindles. The controlled sulfur (≤0.030%) gives consistent machinability on automatic lathes, and the Q&T properties provide the fatigue resistance needed for rotating components.
1.5–4.0 mm strip, fine-blanked into gear blanks, then hobbed or shaped, quenched and tempered (or induction-hardened at the tooth flanks). C45E is the standard gear material for low-to-medium load applications — conveyor sprockets, appliance gears, power tool gears, small transmission gears. For higher loads or larger modules, 42CrMo or carburizing grades are used. See our power tool components guide for gear material selection.
Cold-headed from C45E wire or strip, then quenched and tempered to property class 8.8 (tensile ≥800 MPa, yield ≥640 MPa). C45E is the standard material for property class 8.8 bolts and studs in the M6–M36 range. The 0.42–0.50% carbon provides the hardenability needed for full through-hardening in bolt sections, while the controlled sulfur ensures consistent heading and rolling performance.
2.0–4.0 mm strip, blanked or forged from C45E bar, then quenched and tempered to 600–800 MPa. Connecting rods in small engines, lever arms in machinery, and linkage components all rely on C45E's balance of strength and toughness. The elongation of 12–18% after standard Q&T provides enough ductility to absorb shock loads without brittle fracture.
2.0–4.0 mm strip, blanked into wrench and tool profiles, then quenched and low-temperature tempered (200–300°C) to 45–52 HRC at the working end. C45E is the standard material for combination wrenches, spanners, screwdriver blades and plier jaws — the high hardness at the contact surface resists rounding and wear, while the tempered core provides enough toughness to resist breakage under torque.
0.8–3.0 mm strip for machinery brackets, lever plates, cam followers and structural components that require moderate strength after Q&T. C45E is often used as a direct upgrade from low-carbon SAE1020 when the part needs more load-bearing capacity without the cost of alloy steel. Parts are typically blanked in the spheroidized condition, then quenched and tempered as a subassembly.
The standard Q&T route for C45E, plus the processing we perform before delivery.
Heat to 820–860°C and hold for sufficient time (typically 5–15 minutes per mm of section) to fully transform to austenite. Too low → incomplete hardening; too high → grain growth and brittleness. For strip, continuous furnace lines with controlled atmosphere prevent decarburization.
Water quench for sections up to ~20 mm to achieve full through-hardness; oil quench for thinner sections or where dimensional stability is critical. Thin strip (≤1 mm) may harden fully in oil. Quench distortion is managed by fixturing or press-quenching for flat parts.
Temper at 500–650°C for 1–2 hours to reach 600–800 MPa tensile with good toughness — the standard condition for shafts, gears and bolts. For wear parts and hand tools, temper at 200–300°C to reach 45–52 HRC. Avoid the 300–400°C temper range where tempered martensite embrittlement can occur.
We supply C45E in the spheroidized (soft-annealed) condition for blanking and forming, with hardness ≤207 HB. Precision slitting to your width from 6 mm upward, with burr direction and width tolerance documented on the MTC. Read our spheroidizing guide for how the anneal affects blanking performance.
These grade families share material, processing or application territory with C45E.
SAE1035 / SAE1050 / C45E grades, hardenable for load-bearing machined and blanked components.
42CrMo / 20CrMnTi grades with deep hardenability for large-section shafts, gears and structural components.
SAE1070 / SAE1078 / SK5 grades with high hardness and wear resistance for springs, cutting edges and saw blades.
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