Steel 20Cr4 +A vs 20Cr4 +AC
Steel · 20Cr4 temper comparison
20Cr4 +A and 20Cr4 +AC are two conditions of the same steel grade, 20Cr4: +A (annealed) versus +AC (spheroidize annealed). The chemistry is identical, so every difference below comes from the condition. 20Cr4 +A is the stronger of the two: yield strength 350 MPa (50.8 ksi) against 310 MPa (45 ksi) for 20Cr4 +AC, about 13% more; tensile strength follows at 560 MPa (81.2 ksi) vs 500 MPa (72.5 ksi). In exchange, 20Cr4 +AC is the more ductile: elongation 28% versus 25% for 20Cr4 +A, and 20Cr4 +A is harder (170 HB vs 155 HB).
20Cr4 +AChoose it when strength drives the design.
20Cr4 +ACChoose it when the part is bent, formed or impact-loaded.
20Cr4 +A vs 20Cr4 +AC: 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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 350 MPa50.8 ksi · Shear Strength 380 MPa55.1 ksi · Fatigue Strength (Endurance Limit) 270 MPa39.2 ksi · Fracture Toughness (K_IC) 90 MPa·√m81.9 ksi·√in · Hardness, Vickers 180 HV
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 44 W/m·K25.4 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.8 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Max Service Temperature (continuous) 200°C392 °F · Min Service Temperature -25°C-13 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 55 / 100 · Castability 25 / 100 · Brazeability / Solderability 65 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 31 MJ/kg13,328 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 55 L/kg6.6 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.
20Cr4 +A vs 20Cr4 +AC — frequently asked
Is 20Cr4 +A stronger than 20Cr4 +AC?
Yes. 20Cr4 +A has a typical yield strength of 350 MPa (50.8 ksi) against 310 MPa (45 ksi) for 20Cr4 +AC — about 13% more. Tensile strength is 560 MPa (81.2 ksi) vs 500 MPa (72.5 ksi).
Which condition does FabDigit quote by default, +A or +AC?
+A is the default 20Cr4 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, 20Cr4 +A or 20Cr4 +AC?
20Cr4 +A. Its machinability rates good (58/100) against fair (52/100) for 20Cr4 +AC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 20Cr4 +A and 20Cr4 +AC 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.