Steel GCr15SiMn QT-S1
Heat-treated state
EN 100CrMn6
QT-S1 = q&T stabilized S1
Pick the ~250 °C stabilizing temper for bearings running to about 200 °C where dimensional stability outranks hardness; 57 HRC reduces hardness and fatigue life.
Values for the QT-S1 condition
Other GCr15SiMn tempers and conditions
GCr15SiMn is listed in 9 conditions; see the grade overview at GCr15SiMn.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Order the standard supply condition — fine spheroidal carbides at 195 HB — for turning, cold extrusion and as preparation for final hardening. | 420 | 750 | 22 | 195 HB | — |
Normalized | Normalize after forging to break up carbide networks and refine grain at 300 HB; treat it as a pre-treatment before spheroidize annealing, not a machining condition. | 560 | 980 | 12 | 31 HRC | 7.5 % IACS |
Hot rolled | Take the as-rolled or as-forged blank only as raw stock; hardness reaches 330 HB and is uneven, so spheroidize annealing is required before machining. | 620 | 1,050 | 10 | 35 HRC | 7.5 % IACS |
Cold drawn | Choose annealed-then-cold-drawn bar for close size and good surface when machining small roller and pin blanks directly, accepting 240 HB and low formability. | 700 | 880 | 10 | 22 HRC | 7.5 % IACS |
QT-S1This page Q&T stabilized S1 | Pick the ~250 °C stabilizing temper for bearings running to about 200 °C where dimensional stability outranks hardness; 57 HRC reduces hardness and fatigue life. | 1,750 | 2,000 | 3 | 57 HRC | 6 % IACS |
Q&T 61-64 HRC | Specify the standard finished-bearing route — oil quench from 820–840 °C plus 150–180 °C temper — for peak 62 HRC and contact fatigue life in rings and rollers up to 120 °C. | 1,900 | 2,300 | 1 | 62 HRC | 36 W/m·K |
Martempered () + temper, 60-63 HRC | Choose salt-bath martempering plus tempering for thin-wall, large-diameter rings where distortion and quench cracking must be limited, with 61 HRC close to direct quenching. | 1,950 | 2,250 | 1 | 61 HRC | 5.6 % IACS |
Q&T 58-61 HRC | Use the higher 200–230 °C temper on large or heavily loaded rings, trading a little hardness (59 HRC) for toughness and dimensional stability up to 150 °C. | — | 2,150 | — | 59 HRC | — |
Austempered to lower bainite, 58-62 HRC | Austemper to lower bainite at 58–62 HRC when impact, contaminated lubrication or high compressive surface stress govern — rolling mill, railway and shock-loaded bearings. | — | 2,200 | — | 60 HRC | — |
What is GCr15SiMn QT-S1?
GCr15SiMn QT-S1 is GCr15SiMn heat treated to QT-S1 — pick the ~250 °C stabilizing temper for bearings running to about 200 °C where dimensional stability outranks hardness; 57 HRC reduces hardness and fatigue life. GCr15SiMn QT-S1 has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 3% and the elastic modulus is 208 GPa (30.2 Msi). GCr15SiMn QT-S1 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). A is the default condition FabDigit quotes; QT-S1 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 88/100, better than 100% of steel grades
- High strength — 1,750 MPa (254 ksi), better than 99% of steel grades
Limitations
- Difficult to weld — 3/100, worse than 100% of steel grades
- Limited ductility — 3%, worse than 99% of steel grades
- Limited formability — 3/100, worse than 99% of steel grades
- Low fracture toughness — 23 MPa·√m (20.9 ksi·√in), worse than 98% of steel grades
- Difficult to machine — 13/100, worse than 98% of steel grades
GCr15SiMn QT-S1 properties
Typical room-temperature values for GCr15SiMn QT-S1; 22 are specific to this condition. Other listed values are GCr15SiMn reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
GCr15SiMn QT-S1 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
GCr15SiMn QT-S1 has a yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Elongation at break is 3% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
GCr15SiMn QT-S1 is rated for continuous service to 200°C (392 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
GCr15SiMn QT-S1 conducts electricity at 6 % IACS, worse than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of GCr15SiMn QT-S1 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 25%.
Manufacturability7
GCr15SiMn QT-S1's machinability is not recommended (13/100, worse than 98% of steel grades); weldability not recommended (3/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with GCr15SiMn QT-S1
Is GCr15SiMn easy to machine?
Turn, mill and drill only in the spheroidise-annealed condition (≤229 HB); after hardening restrict work to grinding, CBN hard turning or EDM, and flood-cool grinding to prevent burn and grinding cracks.
Can GCr15SiMn be welded?
With about 1 % C the weldability is very poor and welding should be avoided in principle; if repair is unavoidable, preheat 300–400 °C, use low-hydrogen or nickel-based filler and temper immediately.
Can GCr15SiMn be formed, bent or molded?
In the annealed condition it takes warm upsetting, ring rolling and cold extrusion into raceway blanks; forge at about 1050–1120 °C, finish no lower than 850 °C, then slow-cool plus normalise/spheroidise anneal to break up carbide networks.
What surface finishes work on GCr15SiMn?
Cannot be anodised. Raceways are precision ground and superfinished to a mirror surface, while non-working surfaces are usually black oxided, phosphated, chrome plated or oiled for storage.
GCr15SiMn 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 | 0.95 – 1.05 | 1 |
| Siabove GCr15; raises hardenability and temper stability | 0.45 – 0.75 | 0.6 |
| Mnmarkedly increases hardenability | 0.95 – 1.25 | 1.1 |
| Cr | 1.4 – 1.65 | 1.5 |
| Niresidual element | ≤ 0.3 | — |
| Curesidual element; Cu+Ni less than or equal to 0.50 | ≤ 0.25 | — |
| Moresidual element | ≤ 0.1 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Ooxygen 12 ppm max (quality/high-grade bearing steel) | ≤ 0 | — |
| Fe | balance | — |
GCr15SiMn QT-S1 — frequently asked
What is GCr15SiMn QT-S1 used for?
GCr15SiMn QT-S1 is typically used for large rolling bearings, heavy machinery rollers and rail bearings. In short: higher hardenability than GCr15; heavy-section bearing rings; grind-and-superfinish only.
What is the yield strength of GCr15SiMn QT-S1?
GCr15SiMn QT-S1 has a typical yield strength of 1,750 MPa (254 ksi) and a tensile strength of 2,000 MPa (290 ksi) — stronger than 99% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is GCr15SiMn QT-S1 easy to machine?
Not especially — machinability is rated not recommended (13/100, worse than 98% of steel grades). Turn, mill and drill only in the spheroidise-annealed condition (≤229 HB); after hardening restrict work to grinding, CBN hard turning or EDM, and flood-cool grinding to prevent burn and grinding cracks.
Can GCr15SiMn QT-S1 be welded?
Not readily — weldability is rated not recommended (3/100). With about 1 % C the weldability is very poor and welding should be avoided in principle; if repair is unavoidable, preheat 300–400 °C, use low-hydrogen or nickel-based filler and temper immediately.
What surface finishes work on GCr15SiMn QT-S1?
Cannot be anodised. Raceways are precision ground and superfinished to a mirror surface, while non-working surfaces are usually black oxided, phosphated, chrome plated or oiled for storage.
Can GCr15SiMn QT-S1 be formed, bent or molded?
In the annealed condition it takes warm upsetting, ring rolling and cold extrusion into raceway blanks; forge at about 1050–1120 °C, finish no lower than 850 °C, then slow-cool plus normalise/spheroidise anneal to break up carbide networks.
What is the maximum service temperature of GCr15SiMn QT-S1?
GCr15SiMn QT-S1 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between GCr15SiMn-A and GCr15SiMn-MQ?
A is the default condition — order the standard supply condition — fine spheroidal carbides at 195 HB — for turning, cold extrusion and as preparation for final hardening. MQ: choose salt-bath martempering plus tempering for thin-wall, large-diameter rings where distortion and quench cracking must be limited, with 61 HRC close to direct quenching. Yield strength is 420 MPa in A versus 1,950 MPa in MQ.
Sources
- ISO 683-17 / DIN EN ISO 683-17 (100CrMn6, 1.3520) — ISO (2014)
- ASM Handbook Vol.1 Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Bearing steel grades data (100Cr6 / 100CrMn6) heat treatment and properties — Ovako / SKF (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.