Steel A335 P91 vs SKD61
Steel · grade comparison
Steel A335 P91 and SKD61 are both steel grades, both heat resistant steel. A335 P91 is the stronger of the two: yield strength 700 MPa (102 ksi) against 415 MPa (60.2 ksi) for SKD61, about 69% more; tensile strength follows at 950 MPa (138 ksi) vs 760 MPa (110 ksi). In exchange, SKD61 is the more ductile: elongation 25% versus 14% for A335 P91, and A335 P91 is harder (300 HB vs 215 HB). SKD61 runs hotter in service (400°C vs 200°C continuous). On the shop floor, SKD61 machines more easily (good vs poor) and SKD61 welds better (fair vs poor).
A335 P91Choose it when strength drives the design.
SKD61Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
A335 P91 vs SKD61: 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
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Same in both: Hardness, Vickers 225 HV
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
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Resistivity
Electrical Conductivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
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
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 65 L/kg7.8 gal/lb
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 | A335 P91 | SKD61 |
|---|---|---|
| Sheet metal | Yes | — |
| Default condition | HR | Annealed |
| 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.
A335 P91 vs SKD61 — frequently asked
Is A335 P91 stronger than SKD61?
Yes. A335 P91 has a typical yield strength of 700 MPa (102 ksi) against 415 MPa (60.2 ksi) for SKD61 — about 69% more. Tensile strength is 950 MPa (138 ksi) vs 760 MPa (110 ksi).
Which is cheaper, A335 P91 or SKD61?
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, A335 P91 or SKD61?
SKD61. Its machinability rates good (55/100) against poor (25/100) for A335 P91; for welding the order is SKD61 first (fair, 35/100) then A335 P91 (poor, 20/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in A335 P91 and SKD61 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.