Stainless Steel 418 Q&T-540 vs 418 Q&T-650
Stainless Steel · 418 temper comparison
418 Q&T-540 and 418 Q&T-650 are two conditions of the same stainless steel grade, 418: Q&T-540 (hardened and tempered ~540 °C) versus Q&T-650 (hardened and tempered ~650 °C). The chemistry is identical, so every difference below comes from the condition. 418 Q&T-540 is the stronger of the two: yield strength 1,140 MPa (165 ksi) against 860 MPa (125 ksi) for 418 Q&T-650, about 33% more; tensile strength follows at 1,380 MPa (200 ksi) vs 1,070 MPa (155 ksi). In exchange, 418 Q&T-650 is the more ductile: elongation 18% versus 13% for 418 Q&T-540, and 418 Q&T-540 is harder (42 HRC vs 34 HRC). 418 Q&T-650 runs hotter in service (590°C vs 480°C continuous). On the shop floor, 418 Q&T-650 machines more easily (fair vs poor).
418 Q&T-540Choose it when strength drives the design.
418 Q&T-650Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
418 Q&T-540 vs 418 Q&T-650: 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.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 215 GPa31.2 Msi · Shear Modulus 83 GPa12 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.29 · Compressive Strength 880 MPa128 ksi · Shear Strength 660 MPa95.7 ksi · Fracture Toughness (K_IC) 70 MPa·√m63.7 ksi·√in · Hardness, Brinell 320 HB
Physical
Density and transition temperatures.
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,510°C2,750 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 23 W/m·K13.3 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.6 µm/m·K5.9 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 2.5 % IACS · Electrical Resistivity 7×10⁻⁷ Ω·m27.6 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.3 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 30 / 100 · Castability 40 / 100 · Brazeability / Solderability 45 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 57 MJ/kg24,506 BTU/lb · Embodied Carbon (primary production) 5.2 kg CO₂/kg · Embodied Water 200 L/kg24 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.
418 Q&T-540 vs 418 Q&T-650 — frequently asked
Is 418 Q&T-540 stronger than 418 Q&T-650?
Yes. 418 Q&T-540 has a typical yield strength of 1,140 MPa (165 ksi) against 860 MPa (125 ksi) for 418 Q&T-650 — about 33% more. Tensile strength is 1,380 MPa (200 ksi) vs 1,070 MPa (155 ksi).
Which condition does FabDigit quote by default, Q&T-540 or Q&T-650?
Q&T-650 is the default 418 condition in the FabDigit quote flow. 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, 418 Q&T-540 or 418 Q&T-650?
418 Q&T-650. Its machinability rates fair (35/100) against poor (22/100) for 418 Q&T-540.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 418 Q&T-540 and 418 Q&T-650 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.