Steel 20Cr4
EN 20Cr4
20Cr4 (1.7027, 20Cr, SAE 5120) is a chromium case-hardening steel of the EN 10084 family, carburized and quenched for a hard case with good rolling-contact fatigue resistance.
Reference datasheet — 20Cr4 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
20Cr4 tempers and conditions
20Cr4 is supplied in 8 conditions, soft to hard. +A 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 |
|---|---|---|---|---|---|---|
Spheroidize annealed | Pick when the part is cold extruded, headed or deep-drawn before carburizing — lowest hardness and best cold formability. | 310 | 500 | 28 | 155 HB | — |
Treated to a ferrite-pearlite structure within a specified hardness… | Choose for consistent, repeatable machining (uniform F-P microstructure) on automatic lathes and gear hobbing lines. | 345 | 560 | 24 | 165 HB | 7.8 % IACS |
+ADefault Annealed | Standard stock condition for bar and tube: soft, machinable, ready for carburizing after part machining. | 350 | 560 | 25 | 170 HB | — |
Supplied to specified hardenability (Jominy) band | Specify for carburized gears and races where case/core hardness after quench must be predictable (Jominy end-quench limits guaranteed). | 360 | 580 | 23 | 42 HRC | 7.8 % IACS |
Treated to a specified hardness range | Order when the mill must guarantee a narrow delivery hardness band for automated machining or cold drawing. | 380 | 590 | 22 | 180 HB | 7.8 % IACS |
Normalized | Use for grain refinement and uniform machining response on hot-rolled or forged blanks prior to carburizing. | 400 | 620 | 22 | 12 HRC | 7.8 % IACS |
Cold drawn | Cold-drawn bright bar for close tolerance and better surface finish where only light machining follows. | 570 | 700 | 10 | 215 HB | — |
Carburized, quenched and low-temperature tempered | The in-service condition: hard wear/rolling-contact surface over a tough ~30–40 HRC core for gears, pins and bearing races. | 640 | 900 | 11 | 60 HRC | — |
What is 20Cr4?
20Cr4 (1.7027, 20Cr, SAE 5120) is a chromium case-hardening steel of the EN 10084 family, carburized and quenched for a hard case with good rolling-contact fatigue resistance. Before hardening it runs about 350 MPa yield, 560 MPa tensile, 25 % elongation and 170 HB (87 HRB), which keeps machining, cold heading and extrusion straightforward; typical forms are bar, wire and ring blanks. Once carburized only grinding and EDM are practical, the steel has no corrosion resistance, and welding is limited to the soft condition. 17Cr3 is the lower-carbon alternative for smaller, less loaded parts. 20Cr4 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). 20Cr4 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
What is 20Cr4 used for?
- bearing rings
- gears
- case-hardened shafts
Advantages
- Forms and bends easily — 62/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
20Cr4 properties
Typical room-temperature values for 20Cr4-+A; bars are the position among steel grades.
Physical3
20Cr4 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
20Cr4 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20Cr4 is rated for continuous service to 200°C (392 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
20Cr4 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 20Cr4 takes about 31 MJ of energy and emits 2.1 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 35%.
Manufacturability8
20Cr4's machinability is good (58/100, better than 75% 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. 20Cr4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 20Cr4
Is 20Cr4 easy to machine?
Machine in +A/+FP/+TH before carburizing; carbide or coated HSS, generous coolant, ~60 % of 1212 rating — after case hardening only grinding/EDM is practical.
Can 20Cr4 be welded?
Weldable in the soft condition with low-hydrogen consumables and 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces.
Can 20Cr4 be formed, bent or molded?
Cold heading, extrusion and bending are good in +AC (spheroidized); hot forge 1100–1200 °C and normalize afterwards to restore grain size.
20Cr4 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 | |
| Slower S range available for cleanliness-critical bearing use | ≤ 0.04 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Fe | balance |
What surface finishes work on 20Cr4?
No anodizing (ferrous): protect with oil, phosphate, black oxide, zinc or hard chrome; grind/lap case-hardened surfaces to final size and allow 0.1–0.3 mm stock for distortion.
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 20Cr4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 20Cr4 cost?
20Cr4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
20Cr4 — frequently asked
What is 20Cr4 used for?
20Cr4 is typically used for bearing rings, gears and case-hardened shafts. In short: bearing-race case-hardening grade; good rolling-contact fatigue; cold-heads in spheroidized condition.
What is the yield strength of 20Cr4?
20Cr4 has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 74% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20Cr4 easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in +A/+FP/+TH before carburizing; carbide or coated HSS, generous coolant, ~60 % of 1212 rating — after case hardening only grinding/EDM is practical.
Can 20Cr4 be welded?
Yes — weldability is rated good (55/100). Weldable in the soft condition with low-hydrogen consumables and 150–250 °C preheat plus post-weld stress relief; do not weld carburized surfaces.
What surface finishes work on 20Cr4?
No anodizing (ferrous): protect with oil, phosphate, black oxide, zinc or hard chrome; grind/lap case-hardened surfaces to final size and allow 0.1–0.3 mm stock for distortion.
Can 20Cr4 be formed, bent or molded?
Cold heading, extrusion and bending are good in +AC (spheroidized); hot forge 1100–1200 °C and normalize afterwards to restore grain size.
What is the maximum service temperature of 20Cr4?
20Cr4 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 20Cr4 cost?
20Cr4 is a budget-cost steel ($), 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 (20Cr) — SAC (2015)
- SAE J404 / J1268 — Chemical compositions and hardenability of alloy steels (5120/5120H) — SAE International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing) — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.