Steel M42 vs T8
Steel · grade comparison
Steel M42 and T8 are both steel grades, both tool steel. M42 is the stronger of the two: yield strength 620 MPa (89.9 ksi) against 570 MPa (82.7 ksi) for T8, about 9% more. In exchange, T8 is the more ductile: elongation 15% versus 12% for M42, and M42 is harder (255 HB vs 240 HB). M42 is lighter (7.98 g/cm³ vs 8.6 g/cm³ for T8). On the shop floor, T8 sits in a lower cost tier (premium, $$$) than M42 (specialty, $$$$$).
M42Choose it when strength drives the design, or when weight is the constraint.
T8Choose it when the part is bent, formed or impact-loaded, or when cost is the deciding factor.
M42 vs T8: 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
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 B
Hardness, Rockwell C
Hardness, Vickers
Same in both: Tensile Strength (Ultimate) 900 MPa131 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 Expansion (CTE, 20–100 °C)
Min Service Temperature
Latent Heat of Fusion
Same in both: Thermal Conductivity 22 W/m·K12.7 BTU/hr·ft·°F · Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Max Service Temperature (continuous) 400°C752 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3.1 % IACS · Electrical Resistivity 5.5×10⁻⁷ Ω·m21.7 µΩ·in
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
Formability (cold)
Castability
Polishability
Same in both: Brazeability / Solderability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 90 L/kg10.8 gal/lb
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 8
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 | T8 |
|---|---|---|
| Default condition | Annealed | Annealed |
| Relative cost | $$$$$ Specialty | $$$ Premium |
| 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.
M42 vs T8 — frequently asked
Is M42 stronger than T8?
Yes. M42 has a typical yield strength of 620 MPa (89.9 ksi) against 570 MPa (82.7 ksi) for T8 — about 9% more. Tensile strength is 900 MPa (131 ksi) vs 900 MPa (131 ksi).
Which is cheaper, M42 or T8?
T8 is the lower-cost material: it sits in the premium 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 welds better, M42 or T8?
M42. Its weldability rates poor (20/100) against poor (15/100) for T8.
Ready to make it?
Upload a CAD file and FabDigit prices the part in M42 and T8 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.