Steel 20MnCrS5 · heat-treated state
Steel 20MnCrS5-AC
Properties of the AC condition, compared with the other 20MnCrS5 tempers.
Soft spheroidize-annealed 1.7149 bar/wire with globular carbides for maximum cold-formability and low tool wear before carburizing.
What is 20MnCrS5-AC?
20MnCrS5-AC is 20MnCrS5 heat treated to AC — soft spheroidize-annealed 1.7149 bar/wire with globular carbides for maximum cold-formability and low tool wear before carburizing. 20MnCrS5-AC has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 80% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). 20MnCrS5-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). HR is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- Forms and bends easily — 80/100, better than 92% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 76% of steel grades
Limitations
- Low strength — 320 MPa (46.4 ksi), worse than 80% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 77% of steel grades
20MnCrS5-AC properties
Typical room-temperature values for 20MnCrS5-AC — 37 properties are specific to this condition; the rest are grade-level values shared by every 20MnCrS5 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
20MnCrS5-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
20MnCrS5-AC has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 80% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MnCrS5-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 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
20MnCrS5-AC conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20MnCrS5-AC takes about 26 MJ of energy and emits 1.9 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 35%.
Manufacturability6
20MnCrS5-AC's machinability is good (62/100, better than 89% of steel grades); weldability good (55/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 20MnCrS5 tempers and conditions
20MnCrS5 is also supplied in 8 other conditions. The full side-by-side table is on the 20MnCrS5 overview.
- HRDefaultStandard stock form for gear-blank forging or rough machining before carburizing.450 MPa yield · 200 HB
- Q&TReference core condition after 860–900 °C oil quench and low temper — the strength the carburized part's core reaches.800 MPa yield · 36 HRC
- CHFinal service condition for gears and splines: 58–62 HRC wear-resistant case over a tough 30–42 HRC core.800 MPa yield · 60 HRC
- CDChoose for close tolerance, bright bar going straight to CNC turning of small shafts and pins.620 MPa yield · 230 HB
- AC-CSpheroidize-annealed then cold-drawn 1.7149 bright bar: raised strength and close tolerances with good chip control from the sulfur addition.500 MPa yield · 185 HB
- NormalizedUse to homogenise forgings and refine grain before carburizing; uniform machinability and low distortion.440 MPa yield · 195 HB
- AnnealedPick for heavy chip removal, cold extrusion or hobbing before carburizing; guaranteed max hardness per EN 10084.370 MPa yield · 180 HB
- ACSoft spheroidize-annealed 1.7149 bar/wire with globular carbides for maximum cold-formability and low tool wear before carburizing.320 MPa yield · 150 HB
Working with 20MnCrS5-AC
Is 20MnCrS5 easy to machine?
Best turned/hobbed in the soft-annealed (≤217 HB) state; the 0.02–0.04 % S gives short chips and ~10 % better tool life than 20MnCr5, but finish carburized surfaces need grinding.
Can 20MnCrS5 be welded?
Weldable only with care — preheat ~200–250 °C, low-hydrogen consumables and post-weld stress relief; sulfur raises hot-cracking risk, so avoid welding on carburized zones.
Can 20MnCrS5 be formed, bent or molded?
Cold extrusion and upsetting are practical after spheroidise annealing; hot forge at 1100–1150 °C and normalize afterwards to control grain size before carburizing.
What surface finishes work on 20MnCrS5?
No corrosion resistance as-machined — protect with oil, manganese phosphate, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement); shot peening after case hardening markedly raises bending fatigue.
20MnCrS5 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 |
|---|---|---|
| C | 0.17 – 0.22 | 0.2 |
| Simax per EN 10084 | ≤ 0.4 | 0.25 |
| Mn | 1.1 – 1.4 | 1.25 |
| P | ≤ 0.03 | 0.02 |
| Sdeliberate S addition for machinability (the 'S' in the grade name) | 0.02 – 0.04 | 0.03 |
| Cr | 1 – 1.3 | 1.15 |
| Fe | balance | — |
20MnCrS5-AC — frequently asked
What is 20MnCrS5-AC used for?
20MnCrS5-AC is typically used for gears, shafts and pins. In short: carburizing Cr-Mn-S bar.
What is the yield strength of 20MnCrS5-AC?
20MnCrS5-AC has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 80% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 20MnCrS5-AC easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Best turned/hobbed in the soft-annealed (≤217 HB) state; the 0.02–0.04 % S gives short chips and ~10 % better tool life than 20MnCr5, but finish carburized surfaces need grinding.
Can 20MnCrS5-AC be welded?
Yes — weldability is rated good (55/100). Weldable only with care — preheat ~200–250 °C, low-hydrogen consumables and post-weld stress relief; sulfur raises hot-cracking risk, so avoid welding on carburized zones.
What surface finishes work on 20MnCrS5-AC?
No corrosion resistance as-machined — protect with oil, manganese phosphate, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement); shot peening after case hardening markedly raises bending fatigue.
Can 20MnCrS5-AC be formed, bent or molded?
Cold extrusion and upsetting are practical after spheroidise annealing; hot forge at 1100–1150 °C and normalize afterwards to control grain size before carburizing.
What is the maximum service temperature of 20MnCrS5-AC?
20MnCrS5-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.
What is the difference between 20MnCrS5-HR and 20MnCrS5-CH?
HR is the default condition — standard stock form for gear-blank forging or rough machining before carburizing. CH: final service condition for gears and splines: 58–62 HRC wear-resistant case over a tough 30–42 HRC core. Yield strength is 450 MPa in HR versus 800 MPa in CH.
Can FabDigit make parts in 20MnCrS5-AC?
Yes — 20MnCrS5-AC is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- EN 10277 / EN 10083 related bright bar and heat-treatment delivery conditions — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Mn-Cr steels) — ASM International (1991)
- Case hardening steel 20MnCr5 / 20MnCrS5 (1.7147/1.7149) datasheet — Deutsche Edelstahlwerke / Ovako (2021)
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.