Stainless Steel 420 Hardened & Tempered vs 420 Stress Relieved
Stainless Steel · 420 temper comparison
420 Hardened & Tempered and 420 Stress Relieved are two conditions of the same stainless steel grade, 420: Hardened & Tempered (quenched and tempered) versus Stress Relieved. The chemistry is identical, so every difference below comes from the condition. 420 Hardened & Tempered is the stronger of the two: yield strength 1,400 MPa (203 ksi) against 950 MPa (138 ksi) for 420 Stress Relieved, about 47% more; tensile strength follows at 1,650 MPa (239 ksi) vs 1,200 MPa (174 ksi). In exchange, 420 Stress Relieved is the more ductile: elongation 9% versus 8% for 420 Hardened & Tempered, and 420 Stress Relieved is harder (375 HB vs 200 HB). On the shop floor, 420 Stress Relieved machines more easily (30 vs 20 out of 100) and 420 Hardened & Tempered welds better (poor vs not recommended).
420 Hardened & TemperedChoose it when strength drives the design, or when it will be welded.
420 Stress RelievedChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
420 Hardened & Tempered vs 420 Stress Relieved: 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.
420 Hardened & Tempered420 Stress Relieved
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
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 · Hardness, Rockwell B 93 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,454°C2,649 °F · Liquidus Temperature 1,510°C2,750 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.3 µm/m·K5.7 µin/in·°F · Latent Heat of Fusion 260 J/g112 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · 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) -0.3 V · Corrosion Resistance 48 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Polishability
Same in both: Castability 45 / 100 · Brazeability / Solderability 40 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 55 MJ/kg23,646 BTU/lb · Embodied Carbon (primary production) 3.5 kg CO₂/kg · Embodied Water 250 L/kg30 gal/lb · Typical Recycled Content 45%
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.
420 Hardened & Tempered vs 420 Stress Relieved — frequently asked
Is 420 Hardened & Tempered stronger than 420 Stress Relieved?
Yes. 420 Hardened & Tempered has a typical yield strength of 1,400 MPa (203 ksi) against 950 MPa (138 ksi) for 420 Stress Relieved — about 47% more. Tensile strength is 1,650 MPa (239 ksi) vs 1,200 MPa (174 ksi).
Which condition does FabDigit quote by default, Hardened & Tempered or Stress Relieved?
Annealed is the default 420 condition in the FabDigit quote flow (neither Hardened & Tempered nor Stress Relieved). 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, 420 Hardened & Tempered or 420 Stress Relieved?
420 Stress Relieved, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for 420 Hardened & Tempered; for welding the order is 420 Hardened & Tempered first (poor, 25/100) then 420 Stress Relieved (not recommended, 12/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 420 Hardened & Tempered and 420 Stress Relieved 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.