Steel H21 vs SUH660
Steel · grade comparison
Steel H21 and SUH660 are both steel grades, both heat resistant steel. SUH660 is the stronger of the two: yield strength 725 MPa (105 ksi) against 620 MPa (89.9 ksi) for H21, about 17% more; tensile strength follows at 1,010 MPa (146 ksi) vs 900 MPa (131 ksi). SUH660 is the more ductile: elongation 22% versus 18% for H21, and SUH660 is harder (290 HB vs 220 HB). SUH660 is lighter (7.94 g/cm³ vs 8.28 g/cm³ for H21) and SUH660 runs hotter in service (700°C vs 450°C continuous). On the shop floor, H21 machines more easily (fair vs poor) and SUH660 welds better (good vs fair).
H21Choose it when the part is machined in volume.
SUH660Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
H21 vs SUH660: 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
Shear Modulus
Bulk Modulus
Poisson's Ratio
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, Brinell
Hardness, Rockwell B
Hardness, Rockwell C
Hardness, Vickers
Same in both: Reduction in Area 40%
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Galvanic Potential (seawater, vs SCE)
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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.
Manufacturing and finishing
| Capability | H21 | SUH660 |
|---|---|---|
| Sheet metal | — | Yes |
| Default condition | Annealed | STA |
| Relative cost | $$ Standard | $$ Standard |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
H21 vs SUH660 — frequently asked
Is SUH660 stronger than H21?
Yes. SUH660 has a typical yield strength of 725 MPa (105 ksi) against 620 MPa (89.9 ksi) for H21 — about 17% more. Tensile strength is 1,010 MPa (146 ksi) vs 900 MPa (131 ksi).
Which is cheaper, H21 or SUH660?
Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, H21 or SUH660?
H21. Its machinability rates fair (40/100) against poor (20/100) for SUH660; for welding the order is SUH660 first (good, 55/100) then H21 (fair, 35/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in H21 and SUH660 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.