Steel M4 Annealed vs M4 H&T 64-66 HRC
Steel · M4 temper comparison
M4 Annealed and M4 H&T 64-66 HRC are two conditions of the same steel grade, M4: Annealed versus H&T 64-66 HRC (hardened & Tempered 64–66 HRC). The chemistry is identical, so every difference below comes from the condition. M4 H&T 64-66 HRC is the stronger of the two: yield strength 2,050 MPa (297 ksi) against 550 MPa (79.8 ksi) for M4 Annealed, about 3.7 times as much; tensile strength follows at 2,350 MPa (341 ksi) vs 880 MPa (128 ksi). In exchange, M4 Annealed is the more ductile: elongation 12% versus 1% for M4 H&T 64-66 HRC, and M4 H&T 64-66 HRC is harder (65 HRC vs 24 HRC). M4 H&T 64-66 HRC runs hotter in service (590°C vs 400°C continuous) and M4 Annealed conducts electricity better (2.9 % IACS vs 2.6 % IACS). On the shop floor, M4 Annealed machines more easily (poor vs not recommended) and M4 Annealed welds better (poor vs not recommended).
M4 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
M4 H&T 64-66 HRCChoose it when strength drives the design, or when the part sees heat.
M4 Annealed vs M4 H&T 64-66 HRC: 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)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 84 GPa12.2 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.28 · Hardness, Brinell 250 HB
Physical
Density and transition temperatures.
Same in both: Density 7.97 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,250°C2,282 °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) 11 µm/m·K6.1 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · 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
Same in both: Galvanic Potential (seawater, vs SCE) -0.58 V
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 45 / 100 · Polishability 50 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 58 MJ/kg24,936 BTU/lb · Embodied Carbon (primary production) 4.2 kg CO₂/kg · Embodied Water 110 L/kg13.2 gal/lb · Typical Recycled Content 35%
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.
M4 Annealed vs M4 H&T 64-66 HRC — frequently asked
Is M4 H&T 64-66 HRC stronger than M4 Annealed?
Yes. M4 H&T 64-66 HRC has a typical yield strength of 2,050 MPa (297 ksi) against 550 MPa (79.8 ksi) for M4 Annealed — about 3.7 times as much. Tensile strength is 2,350 MPa (341 ksi) vs 880 MPa (128 ksi).
Which condition does FabDigit quote by default, Annealed or H&T 64-66 HRC?
Annealed is the default M4 condition in the FabDigit quote flow. 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 is easier to machine, M4 Annealed or M4 H&T 64-66 HRC?
M4 Annealed. Its machinability rates poor (25/100) against not recommended (3/100) for M4 H&T 64-66 HRC; for welding the order is M4 Annealed first (poor, 15/100) then M4 H&T 64-66 HRC (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in M4 Annealed and M4 H&T 64-66 HRC 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.