Steel G20CrNiMo CH-SR
Heat-treated state
CH-SR = carburized, quenched, sub-zero treated and double tempered
Choose when retained austenite must be minimized for precision bearings and long-term dimensional stability at elevated running temperature.
Values for the CH-SR condition
Other G20CrNiMo tempers and conditions
G20CrNiMo is listed in 7 conditions; see the grade overview at G20CrNiMo.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard GB/T 3203 delivery condition for bearing ring blanks: softest, most uniform structure for turning, boring and cold forming before carburizing. | 400 | 620 | 29 | 190 HB | — |
Normalized | Grain refinement and banding removal on forged rings before carburizing; also used when a tougher machining structure than annealed is wanted. | 430 | 680 | 25 | 14 HRC | 8 % IACS |
Hot rolled | Mill as-rolled bar for forging stock or subsequent heat treatment; hardness too high and non-uniform for finish machining. | 450 | 720 | 22 | 20 HRC | 8 % IACS |
Cold drawn | Small-diameter precision bar for rollers, pins and cages where close tolerance and better surface finish reduce machining allowance. | 620 | 760 | 12 | 22 HRC | 8 % IACS |
Quenched and tempered | Direct-hardened condition for shafts, flanges and non-raceway parts machined from the same bearing-steel stock. | 850 | 1,080 | 14 | 34 HRC | — |
Carburized and hardened | The functional service condition for bearing rings and rollers: hard, compressively stressed deep case on a tough 30–42 HRC core for shock and heavy contact loads. | 950 | 1,250 | 11 | 61 HRC | — |
CH-SRThis page Carburized, quenched, sub-zero treated and double tempered | Choose when retained austenite must be minimized for precision bearings and long-term dimensional stability at elevated running temperature. | 1,050 | 1,300 | 11 | 62 HRC | 7 % IACS |
What is G20CrNiMo CH-SR?
G20CrNiMo CH-SR is G20CrNiMo heat treated to CH-SR — choose when retained austenite must be minimized for precision bearings and long-term dimensional stability at elevated running temperature. G20CrNiMo CH-SR has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,300 MPa (189 ksi) — stronger than 93% of steel grades. Elongation at break is 11% and the elastic modulus is 208 GPa (30.2 Msi). G20CrNiMo CH-SR 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; CH-SR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High strength — 1,050 MPa (152 ksi), better than 93% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 8/100, worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 11%, worse than 89% of steel grades
G20CrNiMo CH-SR properties
Typical room-temperature values for G20CrNiMo CH-SR; 20 are specific to this condition. Other listed values are G20CrNiMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
G20CrNiMo CH-SR 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).
Mechanical14
G20CrNiMo CH-SR has a yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,300 MPa (189 ksi) — stronger than 93% of steel grades. Elongation at break is 11% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
G20CrNiMo CH-SR is rated for continuous service to 180°C (356 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
G20CrNiMo CH-SR conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of G20CrNiMo CH-SR takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
G20CrNiMo CH-SR's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (8/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with G20CrNiMo CH-SR
Is G20CrNiMo easy to machine?
Turn/bore in the annealed ≤229 HB condition with carbide inserts and ample coolant; after carburizing only grinding, honing or CBN hard-turning is practical.
Can G20CrNiMo be welded?
Weldable before carburizing with low-hydrogen consumables, 200–300 °C preheat and post-weld temper; never weld a carburized case.
Can G20CrNiMo be formed, bent or molded?
Hot forge 1100–1180 °C with finish above 900 °C then normalize/anneal; cold forming limited to modest upsetting of annealed stock.
What surface finishes work on G20CrNiMo?
Carburize 920–940 °C to the required case depth, quench in oil/press-quench for rings, temper 160–200 °C, then grind and superfinish raceways; protect with phosphating, black oxide or oil film since the steel has no corrosion resistance.
G20CrNiMo 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 |
|---|---|---|
| Clow carbon core for carburizing | 0.17 – 0.23 | 0.2 |
| Si | 0.15 – 0.4 | 0.27 |
| Mn | 0.6 – 0.9 | 0.75 |
| Cr | 0.35 – 0.65 | 0.5 |
| Nicore toughness | 0.4 – 0.7 | 0.55 |
| Mohardenability, temper resistance | 0.15 – 0.3 | 0.22 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Cu | ≤ 0.25 | — |
| O≤15 ppm total oxygen typical for bearing steel | ≤ 0 | — |
| Fe | balance | — |
G20CrNiMo CH-SR — frequently asked
What is G20CrNiMo CH-SR used for?
G20CrNiMo CH-SR is typically used for large industrial bearings, rail and wind turbine bearings and heavy machinery rollers. In short: deep-case carburizing bearing steel; tougher core than G20CrMo; sized for large sections.
What is the yield strength of G20CrNiMo CH-SR?
G20CrNiMo CH-SR has a typical yield strength of 1,050 MPa (152 ksi) and a tensile strength of 1,300 MPa (189 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is G20CrNiMo CH-SR easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Turn/bore in the annealed ≤229 HB condition with carbide inserts and ample coolant; after carburizing only grinding, honing or CBN hard-turning is practical.
Can G20CrNiMo CH-SR be welded?
Not readily — weldability is rated not recommended (8/100). Weldable before carburizing with low-hydrogen consumables, 200–300 °C preheat and post-weld temper; never weld a carburized case.
What surface finishes work on G20CrNiMo CH-SR?
Carburize 920–940 °C to the required case depth, quench in oil/press-quench for rings, temper 160–200 °C, then grind and superfinish raceways; protect with phosphating, black oxide or oil film since the steel has no corrosion resistance.
Can G20CrNiMo CH-SR be formed, bent or molded?
Hot forge 1100–1180 °C with finish above 900 °C then normalize/anneal; cold forming limited to modest upsetting of annealed stock.
What is the maximum service temperature of G20CrNiMo CH-SR?
G20CrNiMo CH-SR 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 G20CrNiMo-A and G20CrNiMo CH-SR?
A is the default condition — standard GB/T 3203 delivery condition for bearing ring blanks: softest, most uniform structure for turning, boring and cold forming before carburizing. CH-SR: choose when retained austenite must be minimized for precision bearings and long-term dimensional stability at elevated running temperature. Yield strength is 400 MPa in A versus 1,050 MPa in CH-SR.
Sources
- GB/T 3203 / (carburizing bearing steel bar) (2016)
- GB/T 3077 (20CrNiMo) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (8620 data) — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Ni-Cr-Mo steels) — ASM International (1991)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.