Steel M42 vs SKH59
Steel · grade comparison
Steel M42 and SKH59 are both steel grades. Both yield at about 620 MPa — strength does not separate them. M42 runs hotter in service (400°C vs 300°C continuous) and M42 conducts heat better (22 W/m·K vs 19 W/m·K). On the shop floor, M42 machines more easily (fair vs poor) and SKH59 sits in a lower cost tier (high, $$$$) than M42 (specialty, $$$$$).
M42Choose it when the part sees heat, or when the part is machined in volume.
SKH59Choose it when cost is the deciding factor.
M42 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
Bulk Modulus
Yield Strength (0.2% offset)
Reduction in Area
Compressive Strength
Shear Strength
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Same in both: Shear Modulus 86 GPa12.5 Msi · Poisson's Ratio 0.28 · Tensile Strength (Ultimate) 900 MPa131 ksi · Elongation at Break 12% · Fatigue Strength (Endurance Limit) 400 MPa58 ksi · Hardness, Brinell 255 HB · Hardness, Rockwell B 101 HRB · Hardness, Rockwell C 25 HRC · Hardness, Vickers 270 HV
Physical
Density and transition temperatures.
Liquidus Temperature
Same in both: Density 7.98 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,290°C2,354 °F
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
Latent Heat of Fusion
Same in both: Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Same in both: Corrosion Resistance 18 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Castability
Brazeability / Solderability
Same in both: Formability (cold) 10 / 100 · Polishability 80 / 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 Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
Same in both: Specific Strength (UTS / density) 113 kN·m/kg
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 | M42 | SKH59 |
|---|---|---|
| CNC machining | Yes | — |
| Default condition | Annealed | — |
| Relative cost | $$$$$ Specialty | $$$$ High |
| Min. machined wall | 0.8 mm | — |
| Best machined surface | Ra 1.6 µm | — |
| AlCrN | Yes | — |
| AlTiN | Yes | — |
| Black Oxide | Yes | — |
| CVD Al2O3 | Yes | — |
| CVD TiCN | Yes | — |
| CVD TiN | Yes | — |
| Cerakote | Yes | — |
| Chrome Plating | Yes | — |
| CrN | Yes | — |
| DLC | Yes | — |
| E-Coating | Yes | — |
| HVOF Coating | Yes | — |
| Hot-Dip Galvanizing | Yes | — |
| MoS2 | Yes | — |
| Multilayer CVD | Yes | — |
| Nickel Plating | Yes | — |
| PTFE Coating | Yes | — |
| Painting | Yes | — |
They share 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
M42 vs SKH59 — frequently asked
What is the difference between M42 and SKH59?
Steel M42 and SKH59 are both steel grades. Both yield at about 620 MPa — strength does not separate them. M42 runs hotter in service (400°C vs 300°C continuous) and M42 conducts heat better (22 W/m·K vs 19 W/m·K).
Which is cheaper, M42 or SKH59?
SKH59 is the lower-cost material: it sits in the high tier ($$$$) while M42 is specialty ($$$$$). 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, M42 or SKH59?
M42. Its machinability rates fair (38/100) against poor (25/100) for SKH59; for welding the order is M42 first (poor, 20/100) then SKH59 (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in M42 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.