Steel 20NiCrMo7 +S
Heat-treated state
EN 20NiCrMo7
+S = treated for high shearability
Use for coil and bar that will be cold sheared into cold-forging slugs without cracked or dished cut faces.
Values for the +S condition
Other 20NiCrMo7 tempers and conditions
20NiCrMo7 is listed in 10 conditions; see the grade overview at 20NiCrMo7.
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 or deep-drawing blanks where maximum ductility and minimum flow stress are required. | 360 | 560 | 24 | 165 HB | — |
+SThis page Treated for high shearability | Use for coil and bar that will be cold sheared into cold-forging slugs without cracked or dished cut faces. | 390 | 600 | 21 | 178 HB | 8 % IACS |
+ADefault Annealed | Standard stock condition for bar and forging stock: softest state for general machining before carburizing. | 400 | 620 | 20 | 190 HB | — |
Annealed to a ferrite–pearlite structure with specified hardness range | Pick when a uniform ferrite-pearlite microstructure and a narrow hardness band are needed for consistent automatic-lathe machining and predictable distortion. | 420 | 640 | 18 | 185 HB | — |
Supplied with guaranteed hardenability band | Specify for gears and bearing rings where the carburizing shop needs a guaranteed Jominy band so case/core hardness after quench is reproducible. | 420 | 640 | 18 | 43 HRC | 8 % IACS |
Heat treated to a specified hardness range | Order when the mill must guarantee a narrow as-delivered hardness band for machining productivity and tool-life consistency. | 440 | 660 | 17 | 13 HRC | 8 % IACS |
Normalized | Used on forgings to refine and homogenize grain before machining and carburizing; slightly stronger and harder than +A. | 500 | 750 | 16 | 20 HRC | 8 % IACS |
Cold drawn | Cold-drawn bright bar for close tolerance and good surface on turned parts; higher strength but residual stress can cause distortion in carburizing. | 580 | 720 | 12 | 220 HB | 8 % IACS |
quenched and tempered (through-hardened core condition, ~300 HB) | For uncarburized shafts and fasteners made from this grade where a tough, high-strength core alone is sufficient. | 800 | 1,000 | 13 | 31 HRC | — |
Carburized and hardened | The service condition for gears and bearing rings: hard wear-resistant case with compressive residual stress over a tough 350–450 HV core. | 950 | 1,250 | 10 | 60 HRC | 40 W/m·K |
What is 20NiCrMo7 +S?
20NiCrMo7 +S is 20NiCrMo7 heat treated to +S — use for coil and bar that will be cold sheared into cold-forging slugs without cracked or dished cut faces. 20NiCrMo7 +S has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 64% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi). 20NiCrMo7 +S 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). +A is the default condition FabDigit quotes; +S is available on request or by drawing note.
Advantages
- Forms and bends easily — 68/100, better than 83% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- Tough — resists crack growth — 115 MPa·√m (104.7 ksi·√in), better than 77% of steel grades
20NiCrMo7 +S properties
Typical room-temperature values for 20NiCrMo7 +S; 22 are specific to this condition. Other listed values are 20NiCrMo7 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
20NiCrMo7 +S 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
20NiCrMo7 +S has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 64% of steel grades. Elongation at break is 21% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
20NiCrMo7 +S is rated for continuous service to 350°C (662 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
20NiCrMo7 +S conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 20NiCrMo7 +S takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
20NiCrMo7 +S's machinability is good (55/100, better than 62% of steel grades); weldability fair (46/100); formability good (68/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 20NiCrMo7 +S
Is 20NiCrMo7 easy to machine?
Machine in the +A/+FP/+TH soft condition with carbide at moderate speed and generous feed; the tough Ni-bearing matrix is gummy, so use sharp positive geometry and high-pressure coolant, and finish-grind after carburizing.
Can 20NiCrMo7 be welded?
Weldable with low-hydrogen consumables at 200–300 °C preheat plus immediate stress relief; never weld through a carburized case, and avoid welding parts already hardened.
Can 20NiCrMo7 be formed, bent or molded?
Hot forge 1100–1150 °C with slow cooling and normalize afterwards; cold heading and extrusion only in the +AC (spheroidized) or +S condition.
What surface finishes work on 20NiCrMo7?
Case-hardened surfaces are hard ground and honed; unhardened areas are protected by black oxide, phosphate, zinc or oil — bake plated parts at 190 °C to relieve hydrogen.
20NiCrMo7 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 |
| SiSi ≤ 0.40 (bearing-steel practice often ≤0.35) | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| P | ≤ 0.03 | — |
| S≤0.015 for bearing quality per EN ISO 683-17 | ≤ 0.04 | — |
| Cr | 0.35 – 0.65 | 0.5 |
| Ni | 1.6 – 2 | 1.8 |
| Mo | 0.2 – 0.3 | 0.25 |
| Curesidual | ≤ 0.3 | — |
| Fe | balance | — |
20NiCrMo7 +S — frequently asked
What is 20NiCrMo7 +S used for?
20NiCrMo7 +S is typically used for gears, bearings and aerospace shafts. In short: 8620 equivalent case-hardening steel; deep hardenability, tough core; higher alloy cost.
What is the yield strength of 20NiCrMo7 +S?
20NiCrMo7 +S has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 20NiCrMo7 +S easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the +A/+FP/+TH soft condition with carbide at moderate speed and generous feed; the tough Ni-bearing matrix is gummy, so use sharp positive geometry and high-pressure coolant, and finish-grind after carburizing.
Can 20NiCrMo7 +S be welded?
With care — weldability is rated fair (46/100). Weldable with low-hydrogen consumables at 200–300 °C preheat plus immediate stress relief; never weld through a carburized case, and avoid welding parts already hardened.
What surface finishes work on 20NiCrMo7 +S?
Case-hardened surfaces are hard ground and honed; unhardened areas are protected by black oxide, phosphate, zinc or oil — bake plated parts at 190 °C to relieve hydrogen.
Can 20NiCrMo7 +S be formed, bent or molded?
Hot forge 1100–1150 °C with slow cooling and normalize afterwards; cold heading and extrusion only in the +AC (spheroidized) or +S condition.
What is the maximum service temperature of 20NiCrMo7 +S?
20NiCrMo7 +S is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 20NiCrMo7 +A and 20NiCrMo7-CH?
+A is the default condition — standard stock condition for bar and forging stock: softest state for general machining before carburizing. CH: the service condition for gears and bearing rings: hard wear-resistant case with compressive residual stress over a tough 350–450 HV core. Yield strength is 400 MPa in +A versus 950 MPa in CH.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- EN ISO 683-17 — Heat-treatable steels, alloy steels: ball and roller bearing steels — ISO (2014)
- GB/T 3077 — Alloy structural steels (20CrNiMo) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes (carburizing) — ASM International (2013)
- Case-hardening / bearing steel bar datasheets (Ovako, Ascometal, Böhler) — various producers (2023)
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.