Steel 20CrNiMo-NT
Heat-treated state
GB 20CrNiMo · JIS SNCM220
NT = normalized and high-temperature tempered
Preferred pre-heat-treatment for gear blanks: stable hardness 179–217 HB with low residual stress.
Values for the NT condition
Other 20CrNiMo tempers and conditions
20CrNiMo is listed in 8 conditions; see the grade overview at 20CrNiMo.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocked bar condition: softest state for turning, hobbing and cold working before carburizing. | 390 | 610 | 28 | 175 HB | — |
NTThis page Normalized and high-temperature tempered | Preferred pre-heat-treatment for gear blanks: stable hardness 179–217 HB with low residual stress. | 430 | 670 | 25 | 14 HRC | 8 % IACS |
Hot rolled | Cheapest stock condition for forging or blanks that will be normalized/carburized later. | 450 | 700 | 20 | 14 HRC | 8 % IACS |
Normalized | Use to refine forging grain and get uniform machining response before carburizing. | 450 | 700 | 24 | 11 HRC | 8 % IACS |
Cold drawn | Choose for tight-tolerance bright bar and automatic-lathe parts made near-net before case hardening. | 640 | 780 | 12 | 18 HRC | 8 % IACS |
quenched and tempered to medium hardness | For shafts and non-carburized machine parts where toughness and machinability after heat treatment matter. | 780 | 950 | 16 | 30 HRC | — |
Q&T 200 °C | The specification acceptance condition; also used for small direct-hardened parts needing high strength without carburizing. | 880 | 1,080 | 12 | 36 HRC | 40 W/m·K |
Carburized, quenched and low tempered | The end-use gear condition: hard wear-resistant case with high bending fatigue over a tough core. | 950 | 1,200 | 10 | 60 HRC | 38 W/m·K |
What is 20CrNiMo-NT?
20CrNiMo-NT is 20CrNiMo heat treated to NT — preferred pre-heat-treatment for gear blanks: stable hardness 179–217 HB with low residual stress. 20CrNiMo-NT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 51% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). 20CrNiMo-NT 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). A is the default condition FabDigit quotes; NT is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
20CrNiMo-NT properties
Typical room-temperature values for 20CrNiMo-NT; 23 are specific to this condition. Other listed values are 20CrNiMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20CrNiMo-NT 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
20CrNiMo-NT has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 51% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20CrNiMo-NT is rated for continuous service to 400°C (752 °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
20CrNiMo-NT 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 20CrNiMo-NT takes about 33 MJ of energy and emits 2.2 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 25%.
Manufacturability7
20CrNiMo-NT's machinability is good (57/100, better than 71% of steel grades); weldability good (55/100); formability fair (48/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20CrNiMo-NT
Is 20CrNiMo easy to machine?
Machine in the annealed or normalized+tempered state (≈180–210 HB) with carbide tooling; leave grinding stock because carburizing distorts and the finished case is only grindable.
Can 20CrNiMo be welded?
Weldable before carburizing with low-hydrogen consumables, 150–250 °C preheat and post-weld stress relief; welding a carburized surface is not recommended.
Can 20CrNiMo be formed, bent or molded?
Hot forge at 1150–1200 °C, finish above 850 °C and normalize afterwards; cold heading and cold extrusion possible after spheroidize annealing.
What surface finishes work on 20CrNiMo?
No anodizing — protect with phosphate + oil, black oxide, zinc or Zn-Ni plating; shot peening after carburizing markedly raises gear-tooth bending fatigue.
20CrNiMo 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 – 0.23 | 0.2 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.6 – 0.95 | 0.78 |
| Cr | 0.4 – 0.7 | 0.55 |
| Ni | 0.35 – 0.75 | 0.55 |
| Mo | 0.15 – 0.25 | 0.2 |
| Pmax; ≤0.025 for high-grade quality | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Curesidual, max | ≤ 0.3 | — |
| Fe | balance | — |
20CrNiMo-NT — frequently asked
What is 20CrNiMo-NT used for?
20CrNiMo-NT is typically used for automotive gears, shafts and pinions. In short: 8620-equivalent gear steel; best all-round carburizing grade; weldable before carburizing.
What is the yield strength of 20CrNiMo-NT?
20CrNiMo-NT has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 20CrNiMo-NT easy to machine?
Reasonably — machinability is rated good (57/100, better than 71% of steel grades). Machine in the annealed or normalized+tempered state (≈180–210 HB) with carbide tooling; leave grinding stock because carburizing distorts and the finished case is only grindable.
Can 20CrNiMo-NT be welded?
Yes — weldability is rated good (55/100). Weldable before carburizing with low-hydrogen consumables, 150–250 °C preheat and post-weld stress relief; welding a carburized surface is not recommended.
What surface finishes work on 20CrNiMo-NT?
No anodizing — protect with phosphate + oil, black oxide, zinc or Zn-Ni plating; shot peening after carburizing markedly raises gear-tooth bending fatigue.
Can 20CrNiMo-NT be formed, bent or molded?
Hot forge at 1150–1200 °C, finish above 850 °C and normalize afterwards; cold heading and cold extrusion possible after spheroidize annealing.
What is the maximum service temperature of 20CrNiMo-NT?
20CrNiMo-NT 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 20CrNiMo-A and 20CrNiMo CHQT?
A is the default condition — standard stocked bar condition: softest state for turning, hobbing and cold working before carburizing. CHQT: the end-use gear condition: hard wear-resistant case with high bending fatigue over a tough core. Yield strength is 390 MPa in A versus 950 MPa in CHQT.
Sources
- SAE J404 Chemical Compositions of SAE Alloy Steels (8620) — SAE International (2021)
- EN 10084 Case hardening steels (21NiCrMo2, 1.6523) — CEN (2008)
- JIS G 4053 (SNCM220) — JSA (2016)
- 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)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
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.