Steel 20MoCr4 CH-QT
Heat-treated state
EN 20MoCr4
CH-QT = 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.
Values for the CH-QT condition
Other 20MoCr4 tempers and conditions
20MoCr4 is listed in 8 conditions; see the grade overview at 20MoCr4.
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 | — |
CH-QTThis page 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 CH-QT?
20MoCr4 CH-QT is 20MoCr4 heat treated to 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. 20MoCr4 CH-QT has a yield strength of 680 MPa (98.6 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 80% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi). 20MoCr4 CH-QT 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). +AC is the default condition FabDigit quotes; CH-QT is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 75/100, better than 94% of steel grades
- High strength — 680 MPa (98.6 ksi), better than 80% of steel grades
Limitations
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Difficult to machine — 15/100, worse than 98% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
20MoCr4 CH-QT properties
Typical room-temperature values for 20MoCr4 CH-QT; 19 are specific to this condition. Other listed values are 20MoCr4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20MoCr4 CH-QT 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 CH-QT has a yield strength of 680 MPa (98.6 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 80% of steel grades. Elongation at break is 11% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20MoCr4 CH-QT is rated for continuous service to 180°C (356 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
20MoCr4 CH-QT 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 CH-QT 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 CH-QT's machinability is poor (15/100, worse than 98% of steel grades); weldability poor (15/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20MoCr4 CH-QT
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.
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.
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 | — |
20MoCr4 CH-QT — frequently asked
What is 20MoCr4 CH-QT used for?
20MoCr4 CH-QT 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 CH-QT?
20MoCr4 CH-QT has a typical yield strength of 680 MPa (98.6 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20MoCr4 CH-QT easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% 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 CH-QT be welded?
Not readily — weldability is rated poor (15/100). 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 CH-QT?
No anodizing — protect with oil, zinc/zinc-nickel plating, manganese phosphate or black oxide; carburized surfaces are typically hard-ground or honed.
Can 20MoCr4 CH-QT 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 CH-QT?
20MoCr4 CH-QT is rated for continuous use to about 180°C (356 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.