Stainless Steel AUS-8 QT55-57HRC vs AUS-8 QT59-61HRC-CRYO
Stainless Steel · AUS-8 temper comparison
AUS-8 QT55-57HRC and AUS-8 QT59-61HRC-CRYO are two conditions of the same stainless steel grade, AUS-8: QT55-57HRC versus QT59-61HRC-CRYO (Q&T + cryogenic 59–61 HRC). The chemistry is identical, so every difference below comes from the condition. AUS-8 QT59-61HRC-CRYO is the stronger of the two: yield strength 1,850 MPa (268 ksi) against 1,600 MPa (232 ksi) for AUS-8 QT55-57HRC, about 16% more; tensile strength follows at 2,150 MPa (312 ksi) vs 1,900 MPa (276 ksi). In exchange, AUS-8 QT55-57HRC is the more ductile: elongation 3% versus 1.5% for AUS-8 QT59-61HRC-CRYO, and AUS-8 QT59-61HRC-CRYO is harder (700 HV vs 620 HV). AUS-8 QT55-57HRC runs hotter in service (250°C vs 150°C continuous).
AUS-8 QT55-57HRCChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
AUS-8 QT59-61HRC-CRYOChoose it when strength drives the design.
AUS-8 QT55-57HRC vs AUS-8 QT59-61HRC-CRYO: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all stainless steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
AUS-8 QT55-57HRCAUS-8 QT59-61HRC-CRYO
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 40% · Hardness, Brinell 225 HB · Hardness, Rockwell B 97 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 24 W/m·K13.9 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.4 µm/m·K5.8 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -50°C-58 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3 % IACS · Electrical Resistivity 5.5×10⁻⁷ Ω·m21.7 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.35 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Same in both: Weldability 20 / 100 · Formability (cold) 35 / 100 · Castability 25 / 100 · Brazeability / Solderability 45 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 53 MJ/kg22,786 BTU/lb · Embodied Carbon (primary production) 5 kg CO₂/kg · Embodied Water 130 L/kg15.6 gal/lb · Typical Recycled Content 35%
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
AUS-8 QT55-57HRC vs AUS-8 QT59-61HRC-CRYO — frequently asked
Is AUS-8 QT59-61HRC-CRYO stronger than AUS-8 QT55-57HRC?
Yes. AUS-8 QT59-61HRC-CRYO has a typical yield strength of 1,850 MPa (268 ksi) against 1,600 MPa (232 ksi) for AUS-8 QT55-57HRC — about 16% more. Tensile strength is 2,150 MPa (312 ksi) vs 1,900 MPa (276 ksi).
Which condition does FabDigit quote by default, QT55-57HRC or QT59-61HRC-CRYO?
Annealed is the default AUS-8 condition in the FabDigit quote flow (neither QT55-57HRC nor QT59-61HRC-CRYO). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, AUS-8 QT55-57HRC or AUS-8 QT59-61HRC-CRYO?
AUS-8 QT55-57HRC, by a small margin. Both rate not recommended for machinability — 10/100 against 5/100 for AUS-8 QT59-61HRC-CRYO.
Ready to make it?
Upload a CAD file and FabDigit prices the part in AUS-8 QT55-57HRC and AUS-8 QT59-61HRC-CRYO side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.