Steel 41Cr4 +AC (Spheroidize annealed)
Heat-treated state
EN 41Cr4
Pick for cold forming, cold heading of bolts or maximum machined-surface quality — carbides spheroidized for lowest hardness and best ductility.
Values for the +AC condition
Other 41Cr4 tempers and conditions
41Cr4 is listed in 13 conditions; see the grade overview at 41Cr4.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Supplied with specified (Jominy) hardenability for hardening | Choose when the part will be hardened by the fabricator and a guaranteed Jominy band / as-quenched hardness is required (41Cr4H). | — | — | 2 | 55 HRC | — |
+ACThis page Spheroidize annealed | Pick for cold forming, cold heading of bolts or maximum machined-surface quality — carbides spheroidized for lowest hardness and best ductility. | 370 | 610 | 23 | 187 HB | — |
Treated for shearability | Softened bar for cold shearing/blanking of billets before forging or upsetting. | 390 | 640 | 21 | 15 HRC | 8 % IACS |
Annealed | Standard soft-annealed stock for heavy machining, deep drilling or cold working before final Q&T. | 400 | 660 | 20 | 210 HB | 44 W/m·K |
Treated to ferrite-pearlite structure and hardness range | Ordered when a narrow hardness band and consistent chip formation are needed for high-volume automatic machining. | 440 | 720 | 18 | 14 HRC | 8.2 % IACS |
Hot rolled | Cheapest mill condition; buy when you will forge, machine rough and heat treat the part yourself. | 450 | 750 | 16 | 220 HB | — |
Normalized | Uniform fine ferrite-pearlite for stable machining and moderate strength where full Q&T is not required. | 470 | 780 | 17 | 230 HB | — |
+QT | Heavy-section Q&T bar/forging where reduced hardenability lowers achievable strength but toughness stays high. | 560 | 820 | 16 | 24 HRC | — |
Cold drawn | Bright, dimensionally accurate bar for shafts and turned parts where no further heat treatment is planned. | 620 | 780 | 10 | 235 HB | — |
Heat treated to a specified hardness range | Order when the drawing calls out a hardness band (typ. 248–302 HB) rather than tensile properties. | 680 | 920 | 15 | 28 HRC | 7.9 % IACS |
+QTDefault Quenched and tempered | The workhorse condition: oil quench + high temper for shafts, gears, axles and bolts needing ≥660 MPa yield with 35 J toughness. | 750 | 1,000 | 14 | 31 HRC | 42 W/m·K |
+QT + induction surface hardened | Q&T core plus induction-hardened running surfaces for wear-loaded journals, splines and gear teeth. | 750 | 1,000 | 12 | 56 HRC | 7.5 % IACS |
+QT | Small-diameter Q&T bar/wire for high-strength fasteners and pins where full hardening through section is achieved. | 880 | 1,100 | 12 | 36 HRC | — |
What is 41Cr4 +AC?
41Cr4 +AC is 41Cr4 heat treated to +AC — pick for cold forming, cold heading of bolts or maximum machined-surface quality — carbides spheroidized for lowest hardness and best ductility. 41Cr4 +AC has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 70% of steel grades. Elongation at break is 23% and the elastic modulus is 207 GPa (30 Msi). 41Cr4 +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). +QT is the default condition FabDigit quotes; +AC is available on request or by drawing note.
Advantages
- Easy to machine — 66/100, better than 95% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 75% of steel grades
41Cr4 +AC properties
Typical room-temperature values for 41Cr4 +AC; 13 are specific to this condition. Other listed values are 41Cr4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
41Cr4 +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
41Cr4 +AC has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 70% of steel grades. Elongation at break is 23% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
41Cr4 +AC is rated for continuous service to 350°C (662 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
41Cr4 +AC conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 41Cr4 +AC takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 35%.
Manufacturability8
41Cr4 +AC's machinability is good (66/100, better than 95% of steel grades); weldability fair (45/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 41Cr4 +AC
Is 41Cr4 easy to machine?
Machine in +A/+AC/+FP (≤241 HB) for best tool life; in +QT at ~300 HB use coated carbide, 80–140 m/min, rigid setups and finish-grind hardened surfaces.
Can 41Cr4 be welded?
Weldable with care only: preheat 250–350 °C, low-hydrogen consumables, interpass control and temper/stress-relieve at 550–650 °C immediately after welding; avoid welding fully hardened parts.
Can 41Cr4 be formed, bent or molded?
Hot forge 1100–850 °C then normalize or anneal; cold heading and bending only in the spheroidized (+AC) condition with generous radii.
What surface finishes work on 41Cr4?
No natural corrosion protection — use phosphating + oil, zinc or zinc-nickel plating, black oxide, hard chrome or gas nitriding (500–530 °C) for wear; grind and polish to ~Ra 0.2 µm before plating.
41Cr4 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 |
|---|---|---|
| C0.38–0.45 % per EN 10083-3 | 0.38 – 0.45 | 0.41 |
| Simax only | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| Cr | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | 0.02 |
| Smax; 41Cr4 base grade (41CrS4 = 0.020–0.040 S) | ≤ 0.04 | 0.02 |
| Moresidual, not specified in all editions | ≤ 0.1 | — |
| Fe | balance | — |
41Cr4 +AC — frequently asked
What is 41Cr4 +AC used for?
41Cr4 +AC is typically used for gears, shafts, bolts and crankshafts. In short: workhorse Q&T chromium steel; strength-toughness balance at 300 HB; direct SAE 5140 equivalent.
What is the yield strength of 41Cr4 +AC?
41Cr4 +AC has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 610 MPa (88.5 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 13 listed tempers.
Is 41Cr4 +AC easy to machine?
Reasonably — machinability is rated good (66/100, better than 95% of steel grades). Machine in +A/+AC/+FP (≤241 HB) for best tool life; in +QT at ~300 HB use coated carbide, 80–140 m/min, rigid setups and finish-grind hardened surfaces.
Can 41Cr4 +AC be welded?
With care — weldability is rated fair (45/100). Weldable with care only: preheat 250–350 °C, low-hydrogen consumables, interpass control and temper/stress-relieve at 550–650 °C immediately after welding; avoid welding fully hardened parts.
What surface finishes work on 41Cr4 +AC?
No natural corrosion protection — use phosphating + oil, zinc or zinc-nickel plating, black oxide, hard chrome or gas nitriding (500–530 °C) for wear; grind and polish to ~Ra 0.2 µm before plating.
Can 41Cr4 +AC be formed, bent or molded?
Hot forge 1100–850 °C then normalize or anneal; cold heading and bending only in the spheroidized (+AC) condition with generous radii.
What is the maximum service temperature of 41Cr4 +AC?
41Cr4 +AC is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10083-3 Steels for quenching and tempering — Part 3: Alloy steels — CEN (2006)
- EN 10277 / EN 10278 Bright steel products — technical delivery conditions — CEN (2018)
- GB/T 3077 (40Cr) — SAC (2015)
- SAE J404 Chemical Compositions of SAE Alloy Steels (5140) — SAE International (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Engineering steel 1.7035 / 41Cr4 data sheet — Ovako / Deutsche Edelstahlwerke (typical producer sheets) (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.