Stainless Steel 9Cr18MoV-QT57
Hardness band
GB 9Cr18MoV
QT57 = q&T 55–58 HRC
The workhorse hardened condition for knives, scissors, surgical blades and stainless bearing rings.
Values for the QT57 condition
Other 9Cr18MoV tempers and conditions
9Cr18MoV is listed in 6 conditions; see the grade overview at 9Cr18MoV.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocking condition for bar, strip and forging stock; soft enough to machine and blank before hardening. | 430 | 760 | 18 | 225 HB | — |
Cold drawn | Cold-drawn bar or cold-rolled strip for tighter tolerance and better surface before hardening; slightly harder and stronger than mill-annealed. | 650 | 900 | 10 | 27 HRC | 2.9 % IACS |
Q&T 45–50 HRC | Toughness-biased condition for shafts, valve parts and pins where impact matters more than edge retention; corrosion resistance is reduced by the high temper. | 1,250 | 1,500 | 6 | 47 HRC | — |
Q&T 50–55 HRC | Balanced hardness/toughness for tooling, nozzles and heavier blades that must survive shock loads. | 1,500 | 1,750 | 4 | 53 HRC | — |
QT57This page Q&T 55–58 HRC | The workhorse hardened condition for knives, scissors, surgical blades and stainless bearing rings. | 1,650 | 1,900 | 3 | 57 HRC | — |
Q&T 58–61 HRC | Maximum hardness/wear condition (sub-zero treated to remove retained austenite) for razor blades, precision bearings and gauges; very brittle. | 1,750 | 2,000 | 2 | 59 HRC | — |
What is 9Cr18MoV-QT57?
9Cr18MoV-QT57 is 9Cr18MoV heat treated to QT57 — the workhorse hardened condition for knives, scissors, surgical blades and stainless bearing rings. 9Cr18MoV-QT57 has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,900 MPa (276 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi). 9Cr18MoV-QT57 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F). A is the default condition FabDigit quotes; QT57 is available on request or by drawing note.
Advantages
- High strength — 1,650 MPa (239 ksi), better than 100% of stainless steel grades
- Polishes to a fine finish — 88/100, better than 100% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Conducts heat well — 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades
Limitations
- Limited ductility — 3%, worse than 100% of stainless steel grades
- Low fracture toughness — 21 MPa·√m (19.1 ksi·√in), worse than 100% of stainless steel grades
- Limited service temperature — 180°C (356 °F), worse than 100% of stainless steel grades
- Difficult to machine — 8/100, worse than 100% of stainless steel grades
- Difficult to weld — 12/100, worse than 99% of stainless steel grades
9Cr18MoV-QT57 properties
Typical room-temperature values for 9Cr18MoV-QT57; 15 are specific to this condition. Other listed values are 9Cr18MoV reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
9Cr18MoV-QT57 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
9Cr18MoV-QT57 has a yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,900 MPa (276 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
9Cr18MoV-QT57 is rated for continuous service to 180°C (356 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), better than 81% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
9Cr18MoV-QT57 conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of 9Cr18MoV-QT57 takes about 53 MJ of energy and emits 4.8 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 40%.
Manufacturability7
9Cr18MoV-QT57's machinability is not recommended (8/100, worse than 100% of stainless steel grades); weldability not recommended (12/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 9Cr18MoV-QT57
Is 9Cr18MoV easy to machine?
Machine only in the annealed condition with sharp, rigid setups, low speed and generous coolant; carbide tooling and grinding are required above ~45 HRC.
Can 9Cr18MoV be welded?
Effectively unweldable for structural joints — high carbon promotes cracking; if unavoidable, preheat 250–300 °C, use 309/410NiMo filler and temper immediately after.
Can 9Cr18MoV be formed, bent or molded?
Cold form or blank only when annealed and with generous radii; hot work 1100–850 °C followed by slow cooling and a spheroidize anneal at 850–870 °C.
What surface finishes work on 9Cr18MoV?
Harden 1050–1075 °C, oil/air or vacuum quench (optionally sub-zero) then temper 150–200 °C; grind, polish and passivate (nitric or citric per ASTM A967) — PVD/black oxide also common, anodizing not applicable.
9Cr18MoV 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 1220 | 0.85 – 0.95 | 0.9 |
| Si | ≤ 0.8 | 0.4 |
| Mn | ≤ 0.8 | 0.4 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 17 – 19 | 18 |
| Mo | 1 – 1.3 | 1.15 |
| Vgrain refinement, fine carbides | 0.07 – 0.12 | 0.1 |
| Niresidual | ≤ 0.6 | — |
| Fe | balance | — |
9Cr18MoV-QT57 — frequently asked
What is 9Cr18MoV-QT57 used for?
9Cr18MoV-QT57 is typically used for high-end cutlery, surgical instruments, precision bearings and valve seats. In short: 440B-class blade steel; harder than 8Cr13MoV; wear-resistant bearing stainless.
What is the yield strength of 9Cr18MoV-QT57?
9Cr18MoV-QT57 has a typical yield strength of 1,650 MPa (239 ksi) and a tensile strength of 1,900 MPa (276 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is 9Cr18MoV-QT57 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of stainless steel grades). Machine only in the annealed condition with sharp, rigid setups, low speed and generous coolant; carbide tooling and grinding are required above ~45 HRC.
Can 9Cr18MoV-QT57 be welded?
Not readily — weldability is rated not recommended (12/100). Effectively unweldable for structural joints — high carbon promotes cracking; if unavoidable, preheat 250–300 °C, use 309/410NiMo filler and temper immediately after.
What surface finishes work on 9Cr18MoV-QT57?
Harden 1050–1075 °C, oil/air or vacuum quench (optionally sub-zero) then temper 150–200 °C; grind, polish and passivate (nitric or citric per ASTM A967) — PVD/black oxide also common, anodizing not applicable.
Can 9Cr18MoV-QT57 be formed, bent or molded?
Cold form or blank only when annealed and with generous radii; hot work 1100–850 °C followed by slow cooling and a spheroidize anneal at 850–870 °C.
What is the maximum service temperature of 9Cr18MoV-QT57?
9Cr18MoV-QT57 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 9Cr18MoV-A and 9Cr18MoV-QT60?
A is the default condition — standard stocking condition for bar, strip and forging stock; soft enough to machine and blank before hardening. QT60: maximum hardness/wear condition (sub-zero treated to remove retained austenite) for razor blades, precision bearings and gauges; very brittle. Yield strength is 430 MPa in A versus 1,750 MPa in QT60.
Sources
- GB/T 1220 (2007)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys (440-series martensitic stainless) — ASM International (1990)
- ASM Handbook Vol.13B: Corrosion — Materials — ASM International (2005)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- ASTM A276 / A580 (Type 440B) — ASTM International (2017)
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.