Steel O1 Q&T 57-59 HRC vs O1-SR
Steel · O1 temper comparison
O1 Q&T 57-59 HRC and O1-SR are two conditions of the same steel grade, O1: Q&T 57-59 HRC (Q&T, tempered ~300 °C) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. O1 Q&T 57-59 HRC is the stronger of the two: yield strength 1,750 MPa (254 ksi) against 400 MPa (58 ksi) for O1-SR, about 4.4 times as much; tensile strength follows at 2,050 MPa (297 ksi) vs 690 MPa (100 ksi). In exchange, O1-SR is the more ductile: elongation 25% versus 3% for O1 Q&T 57-59 HRC, and O1 Q&T 57-59 HRC is harder (615 HB vs 200 HB). O1 Q&T 57-59 HRC runs hotter in service (280°C vs 200°C continuous) and O1-SR conducts electricity better (7 % IACS vs 6 % IACS). On the shop floor, O1-SR machines more easily (fair vs not recommended) and O1-SR welds better (poor vs not recommended).
O1 Q&T 57-59 HRCChoose it when strength drives the design, or when the part sees heat.
O1-SRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
O1 Q&T 57-59 HRC vs O1-SR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all 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 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.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Shear Modulus 79 GPa11.5 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Hardness, Rockwell B 94 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,460°C2,660 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.9 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Brazeability / Solderability 45 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 32 MJ/kg13,758 BTU/lb · Embodied Carbon (primary production) 2.4 kg CO₂/kg · Embodied Water 55 L/kg6.6 gal/lb · Typical Recycled Content 40%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
O1 Q&T 57-59 HRC vs O1-SR — frequently asked
Is O1 Q&T 57-59 HRC stronger than O1-SR?
Yes. O1 Q&T 57-59 HRC has a typical yield strength of 1,750 MPa (254 ksi) against 400 MPa (58 ksi) for O1-SR — about 4.4 times as much. Tensile strength is 2,050 MPa (297 ksi) vs 690 MPa (100 ksi).
Which condition does FabDigit quote by default, Q&T 57-59 HRC or SR?
Annealed is the default O1 condition in the FabDigit quote flow (neither Q&T 57-59 HRC nor SR). 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, O1 Q&T 57-59 HRC or O1-SR?
O1-SR. Its machinability rates fair (45/100) against not recommended (12/100) for O1 Q&T 57-59 HRC; for welding the order is O1-SR first (poor, 20/100) then O1 Q&T 57-59 HRC (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in O1 Q&T 57-59 HRC and O1-SR 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.