Steel 41CrS4 +AC (Spheroidize annealed)
Heat-treated state
EN 41CrS4
Pick when carbide spheroidization is needed for the best chip control, cold heading of bolts, or thread rolling before quench and temper.
Values for the +AC condition
Other 41CrS4 tempers and conditions
41CrS4 is listed in 12 conditions; see the grade overview at 41CrS4.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACThis page Spheroidize annealed | Pick when carbide spheroidization is needed for the best chip control, cold heading of bolts, or thread rolling before quench and temper. | 400 | 650 | 23 | 195 HB | — |
Annealed | Softest supply condition for deep drilling, broaching and cold forming before hardening. | 420 | 680 | 20 | 205 HB | — |
Normalized | Uniform ferrite-pearlite structure for stock removal and dimensional stability before final heat treatment. | 460 | 780 | 17 | 235 HB | — |
Hot rolled | Cheapest mill condition, bought when the user performs its own annealing, normalizing or Q&T. | 480 | 800 | 16 | 22 HRC | 8 % IACS |
+QT | Largest Q&T section class of EN 10083-3 for this grade; used for big forged shafts. | 500 | 770 | 18 | 22 HRC | — |
+QT | Heavy-section bar class; accept lower core strength on large diameters. | 550 | 820 | 17 | 24 HRC | — |
+QT | Medium-section Q&T class for larger shafts and flanged parts where full hardening depth is limited. | 620 | 870 | 16 | 27 HRC | — |
Cold drawn | Bright, close-tolerance bar for automatic-lathe turned parts that are hardened afterwards or used as-drawn. | 650 | 800 | 9 | 250 HB | — |
Treated to a specified hardness range | Order when the drawing calls out a hardness band rather than a tensile class, typical for machined hydraulic and gearbox parts. | 700 | 950 | 15 | 30 HRC | — |
+QT 16-40Default +QT | Standard stocked condition: best strength/toughness balance for machined shafts, gears and couplings. | 720 | 980 | 14 | 31 HRC | — |
+QT | Highest-strength Q&T class for small-diameter shafts, pins and high-strength fasteners. | 870 | 1,100 | 12 | 36 HRC | — |
Supplied with specified (standard) hardenability band; typically… | Order +H when Jominy hardenability must be guaranteed; as-quenched martensite gives peak hardness and must be tempered before service. | 1,500 | 1,950 | 2 | 56 HRC | — |
What is 41CrS4 +AC?
41CrS4 +AC is 41CrS4 heat treated to +AC — pick when carbide spheroidization is needed for the best chip control, cold heading of bolts, or thread rolling before quench and temper. 41CrS4 +AC has a yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi). 41CrS4 +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 16-40 is the default condition FabDigit quotes; +AC is available on request or by drawing note.
Advantages
- Easy to machine — 70/100, better than 96% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
- Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 75% of steel grades
41CrS4 +AC properties
Typical room-temperature values for 41CrS4 +AC; 12 are specific to this condition. Other listed values are 41CrS4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
41CrS4 +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
41CrS4 +AC has a yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
41CrS4 +AC is rated for continuous service to 300°C (572 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
41CrS4 +AC conducts electricity at 7.7 % IACS, worse than 65% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 41CrS4 +AC takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 35%.
Manufacturability8
41CrS4 +AC's machinability is very good (70/100, better than 96% of steel grades); weldability poor (25/100); formability fair (48/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 41CrS4 +AC
Is 41CrS4 easy to machine?
Sulfide inclusions give good chip breaking and tool life — turn in +A/+AC at ~150–200 m/min carbide; in +QT (≈30 HRC) drop to 100–140 m/min with rigid setups and positive rake.
Can 41CrS4 be welded?
Poor: 0.02–0.04 % S plus ~0.6 % carbon equivalent promotes hot cracking and hard HAZ — avoid welding, or preheat 250–350 °C, use low-hydrogen consumables and post-weld temper.
Can 41CrS4 be formed, bent or molded?
Cold head or thread-roll only in the +AC/+A condition; hot forge 1050–850 °C, then normalize before quenching from 830–860 °C in oil and tempering 540–680 °C.
What surface finishes work on 41CrS4?
No inherent corrosion resistance — phosphate + oil, black oxide, zinc or Zn-Ni plate (bake to avoid hydrogen embrittlement above 1000 MPa); induction hardening and nitriding are both practicable, hard-chrome plating for shaft journals.
41CrS4 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 10083-3 | 0.38 – 0.45 | 0.41 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| Cr | 0.9 – 1.2 | 1.05 |
| Sdeliberate free-machining addition (vs ≤0.035 max in 41Cr4) | 0.02 – 0.04 | 0.03 |
| P | ≤ 0.03 | 0.02 |
| Fe | balance | — |
41CrS4 +AC — frequently asked
What is 41CrS4 +AC used for?
41CrS4 +AC is typically used for shafts, machined fasteners and hydraulic parts. In short: free-machining 41Cr4; best chip control in family; poor weldability from sulfur.
What is the yield strength of 41CrS4 +AC?
41CrS4 +AC has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 41CrS4 +AC easy to machine?
Yes — machinability is rated very good (70/100, better than 96% of steel grades). Sulfide inclusions give good chip breaking and tool life — turn in +A/+AC at ~150–200 m/min carbide; in +QT (≈30 HRC) drop to 100–140 m/min with rigid setups and positive rake.
Can 41CrS4 +AC be welded?
Not readily — weldability is rated poor (25/100). Poor: 0.02–0.04 % S plus ~0.6 % carbon equivalent promotes hot cracking and hard HAZ — avoid welding, or preheat 250–350 °C, use low-hydrogen consumables and post-weld temper.
What surface finishes work on 41CrS4 +AC?
No inherent corrosion resistance — phosphate + oil, black oxide, zinc or Zn-Ni plate (bake to avoid hydrogen embrittlement above 1000 MPa); induction hardening and nitriding are both practicable, hard-chrome plating for shaft journals.
Can 41CrS4 +AC be formed, bent or molded?
Cold head or thread-roll only in the +AC/+A condition; hot forge 1050–850 °C, then normalize before quenching from 830–860 °C in oil and tempering 540–680 °C.
What is the maximum service temperature of 41CrS4 +AC?
41CrS4 +AC is rated for continuous use to about 300°C (572 °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 — Alloy steels — CEN (2019)
- EN 10277 Bright steel products — technical delivery conditions — CEN (2018)
- GB/T 3077 (40Cr comparable grade) — SAC (2015)
- 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)
- 41CrS4 / 1.7039 engineering steel datasheet — Lucchini RS / Böhler (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.