Stainless Steel AUS-8 QT59-61HRC-CRYO
Heat-treated state
QT59-61HRC-CRYO = q&T + cryogenic 59–61 HRC
Sub-zero treatment converts retained austenite for peak hardness and edge stability; toughness and corrosion margin drop, so keep edges thicker.
Values for the QT59-61HRC-CRYO condition
Other AUS-8 tempers and conditions
AUS-8 is listed in 5 conditions; see the grade overview at AUS-8.
- Annealed
- CR
- QT55-57HRC
- QT57-59HRC
- QT59-61HRC-CRYO
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault mill soft-annealed strip/plate for blanking and machining | The as-supplied condition for knife blanks: soft enough to stamp, laser-cut, drill and grind before heat treatment. | 450 | 760 | 18 | 225 HB | — |
Cold rolled | Precision-rolled thin strip supplied slightly harder than full anneal for clean stamping of thin blades and razor blanks. | 650 | 900 | 10 | 28 HRC | 3 % IACS |
hardened and tempered for maximum toughness | Choose for choppers, machetes, dive knives and thick-spine tools where chip resistance beats edge holding. | 1,600 | 1,900 | 3 | 56 HRC | — |
standard knife hardening (≈1050–1070 °C austenitize, 180–200 °C temper) | The mainstream production-knife condition: best balance of edge retention, toughness and easy field sharpening. | 1,750 | 2,050 | 2 | 58 HRC | — |
QT59-61HRC-CRYOThis page Q&T + cryogenic 59–61 HRC | Sub-zero treatment converts retained austenite for peak hardness and edge stability; toughness and corrosion margin drop, so keep edges thicker. | 1,850 | 2,150 | 1.5 | 60 HRC | — |
What is AUS-8 QT59-61HRC-CRYO?
AUS-8 QT59-61HRC-CRYO is AUS-8 heat treated to QT59-61HRC-CRYO — sub-zero treatment converts retained austenite for peak hardness and edge stability; toughness and corrosion margin drop, so keep edges thicker. AUS-8 QT59-61HRC-CRYO has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 1.5% and the elastic modulus is 200 GPa (29 Msi). AUS-8 QT59-61HRC-CRYO has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; QT59-61HRC-CRYO is available on request or by drawing note.
Advantages
- High strength — 1,850 MPa (268 ksi), better than 100% of stainless steel grades
- High electrical conductivity — 3 % IACS, better than 95% 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 — 1.5%, worse than 100% of stainless steel grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 100% of stainless steel grades
- Limited service temperature — 150°C (302 °F), worse than 100% of stainless steel grades
- Difficult to machine — 5/100, worse than 100% of stainless steel grades
- Difficult to weld — 20/100, worse than 95% of stainless steel grades
AUS-8 QT59-61HRC-CRYO properties
Typical room-temperature values for AUS-8 QT59-61HRC-CRYO; 12 are specific to this condition. Other listed values are AUS-8 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
AUS-8 QT59-61HRC-CRYO has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
AUS-8 QT59-61HRC-CRYO has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 1.5% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
AUS-8 QT59-61HRC-CRYO is rated for continuous service to 150°C (302 °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 10.4 µm/m·K (5.78 µin/in·°F).
Electrical3
AUS-8 QT59-61HRC-CRYO conducts electricity at 3 % IACS, better than 95% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), worse than 62% of stainless steel grades.
Sustainability4
Producing a kilogram of AUS-8 QT59-61HRC-CRYO takes about 53 MJ of energy and emits 5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 35%.
Manufacturability8
AUS-8 QT59-61HRC-CRYO's machinability is not recommended (5/100, worse than 100% of stainless steel grades); weldability poor (20/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AUS-8 QT59-61HRC-CRYO
Is AUS-8 easy to machine?
Machine, drill and profile only in the annealed state with sharp carbide and rigid setups (~45 % of 1212); once hardened, work by CBN/diamond grinding or EDM only.
Can AUS-8 be welded?
Poor weldability — 0.75 % C martensitic steel cracks readily; if unavoidable preheat 250–300 °C, use 309/312 filler and temper immediately, expect a soft/brittle HAZ.
Can AUS-8 be formed, bent or molded?
Blank, laser or waterjet cut and lightly bend in the annealed condition; hot forge 1050–1150 °C, never below ~900 °C, and always slow-cool/anneal after forging.
What surface finishes work on AUS-8?
Grind, then passivate (citric or nitric per ASTM A967) after hardening; takes a fine satin or mirror polish, and accepts stonewash, bead blast, black oxide or PVD/DLC coatings applied below the tempering temperature.
AUS-8 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 | 0.7 – 0.75 | 0.73 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 0.5 | 0.4 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Niaustenite stabiliser, aids toughness | ≤ 0.49 | 0.3 |
| Cr | 13 – 14.5 | 13.75 |
| Mo | 0.1 – 0.31 | 0.2 |
| Vgrain refinement, fine carbides | 0.1 – 0.26 | 0.18 |
| Fe | balance | — |
AUS-8 QT59-61HRC-CRYO — frequently asked
What is AUS-8 QT59-61HRC-CRYO used for?
AUS-8 QT59-61HRC-CRYO is typically used for mid-range production knives, multi-tools and kitchen cutlery. In short: easy-sharpening mid-range blade steel; best formability in family; tougher than 440C-class.
What is the yield strength of AUS-8 QT59-61HRC-CRYO?
AUS-8 QT59-61HRC-CRYO has a typical yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,150 MPa (312 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is AUS-8 QT59-61HRC-CRYO easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of stainless steel grades). Machine, drill and profile only in the annealed state with sharp carbide and rigid setups (~45 % of 1212); once hardened, work by CBN/diamond grinding or EDM only.
Can AUS-8 QT59-61HRC-CRYO be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — 0.75 % C martensitic steel cracks readily; if unavoidable preheat 250–300 °C, use 309/312 filler and temper immediately, expect a soft/brittle HAZ.
What surface finishes work on AUS-8 QT59-61HRC-CRYO?
Grind, then passivate (citric or nitric per ASTM A967) after hardening; takes a fine satin or mirror polish, and accepts stonewash, bead blast, black oxide or PVD/DLC coatings applied below the tempering temperature.
Can AUS-8 QT59-61HRC-CRYO be formed, bent or molded?
Blank, laser or waterjet cut and lightly bend in the annealed condition; hot forge 1050–1150 °C, never below ~900 °C, and always slow-cool/anneal after forging.
What is the maximum service temperature of AUS-8 QT59-61HRC-CRYO?
AUS-8 QT59-61HRC-CRYO 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 AUS-8 Annealed and AUS-8-CR?
Annealed is the default condition — the as-supplied condition for knife blanks: soft enough to stamp, laser-cut, drill and grind before heat treatment. CR: precision-rolled thin strip supplied slightly harder than full anneal for clean stamping of thin blades and razor blanks. Yield strength is 450 MPa in Annealed versus 650 MPa in CR.
Sources
- AUS series stainless knife steel (AUS-6 / AUS-8 / AUS-10) data — Aichi Steel Corporation (2020)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys (martensitic stainless) — ASM International (1990)
- JIS G 4303 / G 4305 — Stainless steel bars and cold-rolled plates, sheets and strip — JSA (2021)
- ASTM A967 — Chemical Passivation Treatments for Stainless Steel Parts — ASTM (2017)
- Machinery's Handbook, machinability ratings for stainless steels — Industrial Press (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.