Steel M42 H&T 68-70 HRC vs M42 Q&T
Steel · M42 temper comparison
M42 H&T 68-70 HRC and M42 Q&T are two conditions of the same steel grade, M42: H&T 68-70 HRC (maximum hardness) versus Q&T (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. M42 H&T 68-70 HRC is the stronger of the two: yield strength 1,800 MPa (261 ksi) against 620 MPa (89.9 ksi) for M42 Q&T, about 190% more. M42 H&T 68-70 HRC is harder — 69 HRC against 65 HRC for M42 Q&T — which matters for wear surfaces and threads. M42 Q&T conducts electricity better (3.1 % IACS vs 2.6 % IACS). On the shop floor, M42 Q&T welds better (poor vs not recommended).
M42 H&T 68-70 HRCChoose it when strength drives the design, or when surface hardness matters.
M42 Q&TChoose it when it will be welded.
M42 H&T 68-70 HRC vs M42 Q&T: 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
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 86 GPa12.5 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.28 · Elongation at Break 0% · Hardness, Brinell 255 HB · Hardness, Rockwell B 101 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.98 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,290°C2,354 °F · Liquidus Temperature 1,420°C2,588 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.8 µm/m·K6 µin/in·°F · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
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)
Same in both: Castability 20 / 100 · Brazeability / Solderability 55 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 62 MJ/kg26,655 BTU/lb · Embodied Carbon (primary production) 4.4 kg CO₂/kg · Embodied Water 90 L/kg10.8 gal/lb · Typical Recycled Content 30%
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.
M42 H&T 68-70 HRC vs M42 Q&T — frequently asked
Is M42 H&T 68-70 HRC stronger than M42 Q&T?
Yes. M42 H&T 68-70 HRC has a typical yield strength of 1,800 MPa (261 ksi) against 620 MPa (89.9 ksi) for M42 Q&T — about 190% more. Tensile strength is 1,900 MPa (276 ksi) vs 2,400 MPa (348 ksi).
Which condition does FabDigit quote by default, H&T 68-70 HRC or Q&T?
Annealed is the default M42 condition in the FabDigit quote flow (neither H&T 68-70 HRC nor Q&T). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which welds better, M42 H&T 68-70 HRC or M42 Q&T?
M42 Q&T. Its weldability rates poor (20/100) against not recommended (5/100) for M42 H&T 68-70 HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in M42 H&T 68-70 HRC and M42 Q&T 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.