Steel GCr9
GB GCr9
GCr9 is a high-carbon (about 1% C) chromium through-hardening bearing steel with lower chromium than GCr15, used as an economical grade for smaller and lighter-duty bearing components.
Reference datasheet — GCr9 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
GCr9 tempers and conditions
GCr9 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 |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocked condition (179–207 HB) for turning, cold forming and ring rolling before hardening. | 390 | 640 | 23 | 190 HB | 44 W/m·K |
Hot rolled | As-rolled bar stock before spheroidizing; cheapest form, hard and coarse-structured, normally re-annealed before machining. | 550 | 900 | 12 | 27 HRC | 7 % IACS |
Normalized | Used to break up carbide networks in forgings before spheroidizing; not a delivery condition for finished parts. | 600 | 1,000 | 10 | 31 HRC | 7 % IACS |
Cold drawn | Precision-size bright bar for automatic-lathe production of rollers, pins and small races. | 600 | 750 | 10 | 20 HRC | 7 % IACS |
Induction hardened | Local surface hardening of larger shafts/raceways where a tough unhardened core is wanted. | 1,000 | 1,200 | 2 | 60 HRC | 6.5 % IACS |
Quenched & tempered, 58–62 HRC | Slightly softer, tougher and more dimensionally stable variant for shock-loaded or warmer-running components. | 1,600 | 1,950 | 2 | 60 HRC | — |
Bainite hardened (austempered), 58–62 HRC | Isothermal salt-bath quench to lower bainite: lower distortion, compressive surface stresses and better toughness for contaminated-lubrication or impact-loaded bearings. | 1,650 | 2,000 | 2.5 | 60 HRC | — |
Quenched & low-temperature tempered, 60–64 HRC | Standard bearing-service condition: oil/martempered from ~830–850 °C and tempered 150–180 °C for maximum wear and rolling-contact fatigue life. | 1,750 | 2,150 | 1 | 62 HRC | 38 W/m·K |
What is GCr9?
GCr9 is a high-carbon (about 1% C) chromium through-hardening bearing steel with lower chromium than GCr15, used as an economical grade for smaller and lighter-duty bearing components. Annealed it runs about 390 MPa yield, 640 MPa tensile and 23% elongation at 190 HB with a thermal conductivity of 44 W/m·K, machines and cold-forms moderately (scores 45), and is quenched and tempered to 58–64 HRC depending on the heat-treat route. The lower chromium content reduces hardenability, so section size is limited, and the steel has no corrosion resistance and is effectively unweldable. GCr15 is the standard alternative for larger rings and rollers. GCr9 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F). GCr9 has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi).
What is GCr9 used for?
- Small ball bearing rings and balls
- Needle roller bearing components
- Light-duty rollers and pins
- Cam followers
- Linear guide balls
- Small wear bushings and sleeves
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
GCr9 properties
Typical room-temperature values for GCr9-A; bars are the position among steel grades.
Physical3
GCr9 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
GCr9 has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Elongation at break is 23% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
GCr9 is rated for continuous service to 150°C (302 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
GCr9 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 GCr9 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
GCr9's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (15/100); formability fair (45/100).
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. GCr9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with GCr9
Is GCr9 easy to machine?
Machine only in the spheroidize-annealed state (179–207 HB) with coated carbide; after hardening use CBN hard turning or grinding.
Can GCr9 be welded?
Effectively unweldable — 1 % C causes quench cracking; if unavoidable, preheat >300 °C, low-hydrogen filler and immediate stress relief.
Can GCr9 be formed, bent or molded?
Cold heading and ring rolling are done after spheroidizing; hot forging at 1050–1100 °C followed by controlled cooling and re-annealing to avoid carbide networks.
GCr9 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 |
|---|---|---|
| Chigh carbon for martensite hardness and carbides | 0.95 – 1.05 | 1 |
| Crlower than GCr15 → shallower hardenability | 0.9 – 1.2 | 1.05 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.2 – 0.4 | 0.3 |
| Pimpurity limit | ≤ 0.03 | |
| Simpurity limit | ≤ 0.02 | |
| Niresidual | ≤ 0.3 | |
| Curesidual | ≤ 0.25 | |
| Moresidual | ≤ 0.1 | |
| Fe | balance |
What surface finishes work on GCr9?
Rust-preventive oil, black oxide, phosphate or thin hard chrome; hardened surfaces lap and superfinish to mirror Ra < 0.05 µm for raceways.
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
How much does GCr9 cost?
GCr9 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.
GCr9 — frequently asked
What is GCr9 used for?
GCr9 is typically used for small ball bearing rings and balls, needle roller bearing components, light-duty rollers and pins, cam followers, linear guide balls and small wear bushings and sleeves. In short: economical alternative to GCr15; for small bearing sections; through-hardens to 64 HRC.
What is the yield strength of GCr9?
GCr9 has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 64% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is GCr9 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine only in the spheroidize-annealed state (179–207 HB) with coated carbide; after hardening use CBN hard turning or grinding.
Can GCr9 be welded?
Not readily — weldability is rated poor (15/100). Effectively unweldable — 1 % C causes quench cracking; if unavoidable, preheat >300 °C, low-hydrogen filler and immediate stress relief.
What surface finishes work on GCr9?
Rust-preventive oil, black oxide, phosphate or thin hard chrome; hardened surfaces lap and superfinish to mirror Ra < 0.05 µm for raceways.
Can GCr9 be formed, bent or molded?
Cold heading and ring rolling are done after spheroidizing; hot forging at 1050–1100 °C followed by controlled cooling and re-annealing to avoid carbide networks.
What is the maximum service temperature of GCr9?
GCr9 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between GCr9-A and GCr9-BQ?
A is the default condition — standard stocked condition (179–207 HB) for turning, cold forming and ring rolling before hardening. BQ: isothermal salt-bath quench to lower bainite: lower distortion, compressive surface stresses and better toughness for contaminated-lubrication or impact-loaded bearings. Yield strength is 390 MPa in A versus 1,650 MPa in BQ.
How much does GCr9 cost?
GCr9 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
- ASTM A295 / A295M High-Carbon Anti-Friction Bearing Steel (51100, 52100) — ASTM International (2014)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- 100Cr6 / 52100 bearing steel bar datasheet — Ovako / (2022)
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.