Steel GCr15 · heat-treated state
Steel GCr15 Q&T
Properties of the Q&T condition, compared with the other GCr15 tempers.
Final bearing condition: maximum hardness, wear and rolling-contact fatigue resistance; brittle, service limited to ~150 °C.
What is GCr15 Q&T?
GCr15 Q&T is GCr15 heat treated to Q&T — final bearing condition: maximum hardness, wear and rolling-contact fatigue resistance; brittle, service limited to ~150 °C. GCr15 Q&T has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 208 GPa (30.2 Msi). GCr15 Q&T has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,420°C (2,588 °F). Annealed is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 95/100, better than 100% of steel grades
- High strength — 1,800 MPa (261 ksi), better than 99% of steel grades
Limitations
- Limited ductility — 1%, worse than 100% of steel grades
- Difficult to machine — 10/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Low fracture toughness — 18 MPa·√m (16.4 ksi·√in), worse than 99% of steel grades
GCr15 Q&T properties
Typical room-temperature values for GCr15 Q&T — 18 properties are specific to this condition; the rest are grade-level values shared by every GCr15 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
GCr15 Q&T has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
GCr15 Q&T has a yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 99% of steel grades. Elongation at break is 1% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
GCr15 Q&T 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 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
GCr15 Q&T conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of GCr15 Q&T 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
GCr15 Q&T's machinability is not recommended (10/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other GCr15 tempers and conditions
GCr15 is also supplied in 6 other conditions. The full side-by-side table is on the GCr15 overview.
- AnnealedDefaultStandard as-supplied condition for bar, tube and wire: soft, uniform globular carbide structure for machining, cold forming and subsequent hardening.420 MPa yield · 195 HB
- Q&TFinal bearing condition: maximum hardness, wear and rolling-contact fatigue resistance; brittle, service limited to ~150 °C.1,800 MPa yield · 62 HRC
- Q&T 200CChoose when slightly lower hardness with better toughness and dimensional stability up to ~200 °C is needed (rollers, cams, heavy shock).1,650 MPa yield · 58 HRC
- Q&T 45HRCUsed for gauge bodies, mandrels and shafts where machinability and toughness matter more than maximum wear resistance.1,250 MPa yield · 44 HRC
Working with GCr15 Q&T
Is GCr15 easy to machine?
Machine in the spheroidized annealed condition (~195 HB) with carbide tools and rigid setups; hardened 60+ HRC parts require CBN hard turning or grinding.
Can GCr15 be welded?
Essentially unweldable in structural terms — 1 % C promotes quench cracking; if unavoidable, preheat 300–400 °C, low-hydrogen filler and immediate stress relief/temper.
Can GCr15 be formed, bent or molded?
Cold heading and ball blanking are done on spheroidized stock; hot forge 1050–1150 °C and cool slowly to avoid carbide network and flake cracking.
What surface finishes work on GCr15?
Grind and superfinish raceways; protect with oil, phosphate or black oxide (chrome/nickel plating needs bake-out to avoid hydrogen embrittlement).
GCr15 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 |
|---|---|---|
| CGB/T 18254 | 0.95 – 1.05 | 1 |
| Cr | 1.4 – 1.65 | 1.5 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.25 – 0.45 | 0.35 |
| Niresidual | ≤ 0.25 | — |
| Curesidual | ≤ 0.25 | — |
| Moresidual | ≤ 0.1 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| O12 ppm max, high-quality bearing steel | ≤ 0 | — |
| Fe | balance | — |
GCr15 Q&T — frequently asked
What is GCr15 Q&T used for?
GCr15 Q&T is typically used for ball bearing rings and balls, roller and needle bearing races, precision machine-tool spindle bearings, cam followers and track rollers, hydraulic pump plungers and pistons and die and punch bushings. In short: bearing Cr-bearing steel.
What is the yield strength of GCr15 Q&T?
GCr15 Q&T has a typical yield strength of 1,800 MPa (261 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is GCr15 Q&T easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% of steel grades). Machine in the spheroidized annealed condition (~195 HB) with carbide tools and rigid setups; hardened 60+ HRC parts require CBN hard turning or grinding.
Can GCr15 Q&T be welded?
Not readily — weldability is rated not recommended (5/100). Essentially unweldable in structural terms — 1 % C promotes quench cracking; if unavoidable, preheat 300–400 °C, low-hydrogen filler and immediate stress relief/temper.
What surface finishes work on GCr15 Q&T?
Grind and superfinish raceways; protect with oil, phosphate or black oxide (chrome/nickel plating needs bake-out to avoid hydrogen embrittlement).
Can GCr15 Q&T be formed, bent or molded?
Cold heading and ball blanking are done on spheroidized stock; hot forge 1050–1150 °C and cool slowly to avoid carbide network and flake cracking.
What is the maximum service temperature of GCr15 Q&T?
GCr15 Q&T 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.
Can FabDigit make parts in GCr15 Q&T?
Yes — GCr15 Q&T is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A295 / A295M High-Carbon Anti-Friction Bearing Steel — ASTM (2014)
- ISO 683-17 / DIN EN ISO 683-17 (100Cr6) — ISO (2014)
- JIS G 4805 (SUJ2) — JISC (2019)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 Fatigue and Fracture — ASM International (1996)
- 100Cr6 / 52100 bearing steel bar datasheet — Ovako / Sandvik (2021)
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.