Steel 20CrMo4
EN 20CrMo4
20CrMo4 (1.3567; AISI 4118, JIS SCM420) is a low-alloy chromium-molybdenum case-hardening steel of the EN 10084 family that develops a hard, wear-resistant case over a tough core after carburizing.
Reference datasheet — 20CrMo4 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the +A condition
20CrMo4 tempers and conditions
20CrMo4 is supplied in 10 conditions, soft to hard. +A is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for cold extrusion/cold heading of gear blanks and pinions — lowest hardness and best cold flow. | 310 | 490 | 26 | 145 HB | — |
Treated for high shearability | Choose for billets that must be cold-sheared into slugs without cracking or burr-tearing on the press line. | 320 | 510 | 25 | 150 HB | 7.5 % IACS |
+ADefault Annealed | Standard stock condition for bar and tube: soft enough for general machining before carburizing. | 360 | 570 | 22 | 170 HB | — |
Treated to ferrite-pearlite structure and hardness range | Pick when a uniform ferrite-pearlite microstructure and predictable chip control for high-volume automatic machining are required. | 370 | 580 | 21 | 165 HB | 7.5 % IACS |
Restricted hardenability (Jominy band) grade, supplied in +A/+TH | Order +H (or +HH/+HL) when case depth and core hardness after carburizing must be statistically repeatable batch to batch. | 370 | 580 | 21 | 43 HRC | 7.5 % IACS |
Treated to a specified hardness range | Ordered when the mill must guarantee a narrow hardness band for automated turning/hobbing lines before carburizing. | 400 | 620 | 20 | 180 HB | 7.5 % IACS |
Normalized | Grain-refined condition used after forging to homogenize structure and minimize carburizing distortion. | 430 | 670 | 20 | 195 HB | — |
Cold drawn | Bright-drawn bar for close tolerance shafts and pins where minimal turning stock is wanted. | 600 | 720 | 11 | 215 HB | — |
Q&T | Used for shafts and fasteners in thin sections where no case is needed but higher core strength than normalized is required. | 800 | 1,000 | 14 | 32 HRC | — |
Carburized, hardened and low-temperature tempered | Final service condition for gears, splines and bearing races: hard wear-resistant case with tough core and high bending fatigue strength. | 850 | 1,150 | 11 | 60 HRC | — |
What is 20CrMo4?
20CrMo4 (1.3567; AISI 4118, JIS SCM420) is a low-alloy chromium-molybdenum case-hardening steel of the EN 10084 family that develops a hard, wear-resistant case over a tough core after carburizing. It is stocked as bar, tube and forging stock in annealed, ferrite-pearlite, treated-for-machining and spheroidized conditions; the soft default values are 360 MPa yield, 570 MPa tensile, 22% elongation and 170 HB (87 HRB), with service to 400 °C. Hardenability is limited in heavy sections, welding needs preheat and PWHT, and there is no corrosion resistance. For larger gears use 20MnCrMo4-2 or 20NiCrMo7. 20CrMo4 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). 20CrMo4 has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 72% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20CrMo4 used for?
- gears
- shafts
- bearing races
- camshafts
20CrMo4 properties
Typical room-temperature values for 20CrMo4-+A; bars are the position among steel grades.
Physical3
20CrMo4 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
20CrMo4 has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 72% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20CrMo4 is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
20CrMo4 conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20CrMo4 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
20CrMo4's machinability is good (55/100, better than 62% of steel grades); weldability good (55/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 20CrMo4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20CrMo4
Is 20CrMo4 easy to machine?
Machine in +A/+FP/+TH before carburizing — carbide inserts, 120–180 m/min turning; after case hardening only grinding, EDM or CBN turning is practical.
Can 20CrMo4 be welded?
Weldable with low-hydrogen consumables at CE ≈ 0.55: preheat 150–250 °C and PWHT at 600–650 °C; never weld carburized surfaces.
Can 20CrMo4 be formed, bent or molded?
Cold heading and extrusion are routine in the +AC/+S spheroidized conditions; hot forge 1150–850 °C followed by normalizing to refine grain.
20CrMo4 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 |
|---|---|---|
| Ccase-hardening carbon level | 0.17 – 0.23 | 0.2 |
| Si | 0.1 – 0.4 | 0.25 |
| MnGB 20CrMo runs lower, 0.40–0.70 | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| Smax; S-grades to 0.020–0.040 for machinability | ≤ 0.04 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.25 | 0.2 |
| Fe | balance |
What surface finishes work on 20CrMo4?
No anodizing — use Mn/Zn phosphating, black oxide, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement above 1000 MPa); shot peening after grinding boosts gear-root fatigue life.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 20CrMo4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 20CrMo4 cost?
20CrMo4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
20CrMo4 — frequently asked
What is 20CrMo4 used for?
20CrMo4 is typically used for gears, shafts, bearing races and camshafts. In short: standard Cr-Mo case-hardening steel; 4118 / SCM420 equivalent; hard case, tough core.
What is the yield strength of 20CrMo4?
20CrMo4 has a typical yield strength of 360 MPa (52.2 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 72% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 20CrMo4 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in +A/+FP/+TH before carburizing — carbide inserts, 120–180 m/min turning; after case hardening only grinding, EDM or CBN turning is practical.
Can 20CrMo4 be welded?
Yes — weldability is rated good (55/100). Weldable with low-hydrogen consumables at CE ≈ 0.55: preheat 150–250 °C and PWHT at 600–650 °C; never weld carburized surfaces.
What surface finishes work on 20CrMo4?
No anodizing — use Mn/Zn phosphating, black oxide, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement above 1000 MPa); shot peening after grinding boosts gear-root fatigue life.
Can 20CrMo4 be formed, bent or molded?
Cold heading and extrusion are routine in the +AC/+S spheroidized conditions; hot forge 1150–850 °C followed by normalizing to refine grain.
What is the maximum service temperature of 20CrMo4?
20CrMo4 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 20CrMo4 +A and 20CrMo4 CARB?
+A is the default condition — standard stock condition for bar and tube: soft enough for general machining before carburizing. CARB: final service condition for gears, splines and bearing races: hard wear-resistant case with tough core and high bending fatigue strength. Yield strength is 360 MPa in +A versus 850 MPa in CARB.
How much does 20CrMo4 cost?
20CrMo4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- GB/T 3077 — Alloy structural steels (20CrMo) — SAC (2015)
- JIS G 4053 — Low-alloyed structural steels (SCM420) — JISC (2016)
- SAE J404 / ASTM A29 — AISI 4118 chemical composition — SAE / ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- Case-hardening steel bar datasheets (Cr-Mo grades) — Ovako / Böhler / Dörrenberg (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.