Steel SKH51 vs SKH59
Steel · grade comparison
Steel SKH51 and SKH59 are both steel grades. SKH59 is the stronger of the two: yield strength 600 MPa (87 ksi) against 550 MPa (79.8 ksi) for SKH51, about 9% more; tensile strength follows at 900 MPa (131 ksi) vs 850 MPa (123 ksi). In exchange, SKH51 is the more ductile: elongation 20% versus 12% for SKH59, and SKH59 is harder (255 HB vs 240 HB). SKH51 runs hotter in service (400°C vs 300°C continuous) and SKH51 conducts heat better (22 W/m·K vs 19 W/m·K). On the shop floor, SKH51 sits in a lower cost tier (premium, $$$) than SKH59 (high, $$$$).
SKH51Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
SKH59Choose it when strength drives the design.
SKH51 vs SKH59: 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
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive 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: Poisson's Ratio 0.28 · Shear Strength 560 MPa81.2 ksi
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)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Latent Heat of Fusion 250 J/g107 BTU/lb
Electrical
Conductivity and insulation.
Electrical Resistivity
Same in both: Electrical Conductivity 2.9 % IACS
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)
Brazeability / Solderability
Polishability
Same in both: Castability 25 / 100
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 | SKH51 | SKH59 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Both take the same 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
SKH51 vs SKH59 — frequently asked
Is SKH59 stronger than SKH51?
Yes. SKH59 has a typical yield strength of 600 MPa (87 ksi) against 550 MPa (79.8 ksi) for SKH51 — about 9% more. Tensile strength is 900 MPa (131 ksi) vs 850 MPa (123 ksi).
Which is cheaper, SKH51 or SKH59?
SKH51 is the lower-cost material: it sits in the premium tier ($$$) while SKH59 is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, SKH51 or SKH59?
SKH51, by a small margin. Both rate poor for machinability — 30/100 against 25/100 for SKH59; for welding the order is SKH51 first (poor, 20/100) then SKH59 (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SKH51 and SKH59 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.