Steel 20MoCr4
EN 20MoCr4
20MoCr4 (1.7321) is a low-carbon Mo-Cr case-hardening steel to EN 10084, comparable to SCM420, with moderate hardenability for medium-sized carburized components.
Reference datasheet — 20MoCr4 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 +AC condition
20MoCr4 tempers and conditions
20MoCr4 is supplied in 8 conditions, soft to hard. +AC is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACDefault Spheroidize annealed | Standard stock condition for bar that will be turned, hobbed or cold formed before carburizing. | 345 | 570 | 22 | 180 HB | 42 W/m·K |
Supplied to the restricted hardenability (Jominy) band | Specify when gear/shaft case-and-core hardness after carburizing must be predictable batch to batch (20MoCr4+H narrow Jominy scatter band). | 355 | 580 | 21 | 42 HRC | 7.8 % IACS |
Heat treated to a ferrite-pearlite structure with hardness range | Choose when a consistent ferrite-pearlite microstructure and stable hardness band are needed for good chip breaking in automatic machining. | 380 | 610 | 20 | 185 HB | — |
Treated for shearability | Pick for coil/bar that must be cold sheared or cropped into blanks without cracking. | 400 | 620 | 18 | 14 HRC | 7.8 % IACS |
Heat treated to a specified hardness range | Order when the machine shop needs a guaranteed narrow hardness band rather than a specified microstructure. | 400 | 640 | 19 | 12 HRC | 7.8 % IACS |
Hot rolled | Cheapest mill delivery condition for parts that will be hot-formed or fully heat treated by the user. | 450 | 700 | 16 | 17 HRC | 7.8 % IACS |
Spheroidize annealed and cold drawn bar | Best choice for precision-ground/turned bar stock and cold-headed blanks: tight tolerance, bright surface, higher as-delivered strength. | 540 | 680 | 11 | 205 HB | — |
Carburized, direct/reheat quenched and low-temperature tempered | The in-service condition: 0.6–1.5 mm case at 58–62 HRC over a tough 800–1100 MPa core for gears, pinions and splined shafts. | 680 | 950 | 11 | 60 HRC | 38 W/m·K |
What is 20MoCr4?
20MoCr4 (1.7321) is a low-carbon Mo-Cr case-hardening steel to EN 10084, comparable to SCM420, with moderate hardenability for medium-sized carburized components. Engineers use it where a tough core is combined with a hard, wear-resistant case; core values in the annealed condition are about 345 MPa yield, 570 MPa tensile, 22 % elongation and 180 HB, with thermal conductivity of 42 W/m·K. Bar, wire and forging stock are the normal forms. It has no corrosion resistance and must not be welded after carburizing; 18CrMo4 is the nearest alternative for smaller sections. 20MoCr4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). 20MoCr4 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 75% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20MoCr4 used for?
- gears
- shafts
- carburized machine parts
- bushings
Advantages
- Easy to machine — 63/100, better than 92% of steel grades
- Forms and bends easily — 62/100, better than 78% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Low strength — 345 MPa (50 ksi), worse than 75% of steel grades
20MoCr4 properties
Typical room-temperature values for 20MoCr4-+AC; bars are the position among steel grades.
Physical3
20MoCr4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
20MoCr4 has a yield strength of 345 MPa (50 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 75% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MoCr4 is rated for continuous service to 300°C (572 °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
20MoCr4 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 20MoCr4 takes about 33 MJ of energy and emits 2.2 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability8
20MoCr4's machinability is good (63/100, better than 92% of steel grades); weldability good (55/100); formability good (62/100).
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. 20MoCr4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20MoCr4
Is 20MoCr4 easy to machine?
Machine in +AC or +FP condition with carbide inserts (150–250 m/min turning); leave grinding stock as carburizing adds 0.05–0.2 % growth and distortion.
Can 20MoCr4 be welded?
Weldable before carburizing with preheat ~200 °C and low-hydrogen consumables (CEV ≈ 0.55); avoid welding on carburized surfaces.
Can 20MoCr4 be formed, bent or molded?
Good hot forgeability at 1100–850 °C and acceptable cold heading in spheroidized condition; normalize at 880–920 °C after forging to refine grain.
20MoCr4 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 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| Smax; low-S variants ordered for cleanliness | ≤ 0.04 | 0.02 |
| Cr | 0.3 – 0.6 | 0.45 |
| Mo | 0.4 – 0.5 | 0.45 |
| Fe | balance |
What surface finishes work on 20MoCr4?
No anodizing — protect with oil, zinc/zinc-nickel plating, manganese phosphate or black oxide; carburized surfaces are typically hard-ground or honed.
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 20MoCr4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.732110084
- Similar grades
- SCM420
How much does 20MoCr4 cost?
20MoCr4 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.
20MoCr4 — frequently asked
What is 20MoCr4 used for?
20MoCr4 is typically used for gears, shafts, carburized machine parts and bushings. In short: medium-section case-hardening steel; tough core, hard case; SCM420 equivalent.
What is the yield strength of 20MoCr4?
20MoCr4 has a typical yield strength of 345 MPa (50 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 75% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20MoCr4 easy to machine?
Reasonably — machinability is rated good (63/100, better than 92% of steel grades). Machine in +AC or +FP condition with carbide inserts (150–250 m/min turning); leave grinding stock as carburizing adds 0.05–0.2 % growth and distortion.
Can 20MoCr4 be welded?
Yes — weldability is rated good (55/100). Weldable before carburizing with preheat ~200 °C and low-hydrogen consumables (CEV ≈ 0.55); avoid welding on carburized surfaces.
What surface finishes work on 20MoCr4?
No anodizing — protect with oil, zinc/zinc-nickel plating, manganese phosphate or black oxide; carburized surfaces are typically hard-ground or honed.
Can 20MoCr4 be formed, bent or molded?
Good hot forgeability at 1100–850 °C and acceptable cold heading in spheroidized condition; normalize at 880–920 °C after forging to refine grain.
What is the maximum service temperature of 20MoCr4?
20MoCr4 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 20MoCr4 +AC and 20MoCr4 CH-QT?
+AC is the default condition — standard stock condition for bar that will be turned, hobbed or cold formed before carburizing. CH-QT: the in-service condition: 0.6–1.5 mm case at 58–62 HRC over a tough 800–1100 MPa core for gears, pinions and splined shafts. Yield strength is 345 MPa in +AC versus 680 MPa in CH-QT.
How much does 20MoCr4 cost?
20MoCr4 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)
- EN 10277 — Bright steel products: technical delivery conditions — CEN (2018)
- EN 10083-1 — Steels for quenching and tempering: general technical delivery conditions — CEN (2006)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4 — Heat Treating (carburizing of Cr-Mo steels) — ASM International (1991)
- Case hardening steel bar datasheets (20MoCr4 / 1.7321) — European long-products mills (2023)
- JIS G 4053 — Low-alloyed structural steels (SCM420) — JISC (2016)
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.