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Aluminum AC2A vs AC4A

Aluminum · grade comparison

Aluminum AC2A and AC4A are both aluminum grades. AC4A is the stronger of the two: yield strength 200 MPa (29 ksi) against 170 MPa (24.7 ksi) for AC2A, about 18% more. AC4A is the more ductile: elongation 3% versus 2% for AC2A, and AC4A is harder (90 HB vs 85 HB). AC4A is lighter (2.68 g/cm³ vs 2.79 g/cm³ for AC2A) and AC2A runs hotter in service (175°C vs 150°C continuous). On the shop floor, AC2A machines more easily (very good vs fair) and AC4A welds better (good vs fair).

AC2AChoose it when the part sees heat, or when the part is machined in volume.

AC4AChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.

AC2A vs AC4A: properties

AC2AAC4A

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

74 GPa10.7 Msi
71 GPa10.3 Msi

Shear Modulus

27.5 GPa4 Msi
26.5 GPa3.8 Msi

Bulk Modulus

72 GPa10.4 Msi
70 GPa10.2 Msi

Tensile Strength (Ultimate)

250 MPa36.3 ksi
260 MPa37.7 ksi

Yield Strength (0.2% offset)

170 MPa24.7 ksi
200 MPa29 ksi

Elongation at Break

2%
3%

Shear Strength

165 MPa23.9 ksi
180 MPa26.1 ksi

Fatigue Strength (Endurance Limit)

75 MPa10.9 ksi
90 MPa13.1 ksi

Charpy V-Notch Impact (RT)

3 J2.2 ft·lbf
4 J3 ft·lbf

Hardness, Brinell

85 HB
90 HB

Compressive Strength

—
205 MPa29.7 ksi

Same in both: Poisson's Ratio 0.33 · Fracture Toughness (K_IC) 18 MPa·√m16.4 ksi·√in

Physical

Density and transition temperatures.

Density

2.79 g/cm³0.1 lb/in³
2.68 g/cm³0.1 lb/in³

Melting Point (Solidus)

516°C961 °F
557°C1,035 °F

Liquidus Temperature

604°C1,119 °F
596°C1,105 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

110 W/m·K63.6 BTU/hr·ft·°F
150 W/m·K86.7 BTU/hr·ft·°F

Latent Heat of Fusion

389 J/g167 BTU/lb
425 J/g183 BTU/lb

Max Service Temperature (continuous)

175°C347 °F
150°C302 °F

Same in both: Specific Heat Capacity 963 J/kg·K0.23 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 21.5 µm/m·K11.9 µin/in·°F · Min Service Temperature -196°C-321 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

27 % IACS
39 % IACS

Electrical Resistivity

6.4×10⁻⁸ Ω·m2.52 µΩ·in
4.4×10⁻⁸ Ω·m1.73 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.75 V
-0.83 V

Corrosion Resistance

42 / 100
58 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

72 / 100
50 / 100

Machinability Rating (AISI 1212 = 100 %)

70%
60%

Weldability

35 / 100
65 / 100

Castability

75 / 100
88 / 100

Polishability

40 / 100
45 / 100

Same in both: Formability (cold) 10 / 100 · Brazeability / Solderability 25 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

200 MJ/kg85,985 BTU/lb
155 MJ/kg66,638 BTU/lb

Embodied Carbon (primary production)

12 kg CO₂/kg
9.5 kg CO₂/kg

Embodied Water

1,150 L/kg138 gal/lb
1,100 L/kg132 gal/lb

Typical Recycled Content

80%
70%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

90 kN·m/kg
97 kN·m/kg

Modulus of Resilience

195 kJ/m³
282 kJ/m³

Thermal Diffusivity

40.9 mm²/s
58.1 mm²/s

Thermal Shock Resistance Index

17
26

Same in both: Specific Stiffness (E / density) 26.5 MN·m/kg

Strength versus weight

Yield strength against density for every aluminum grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

20501002005002.22.42.62.83Density (g/cm³)Yield strength (MPa) — log scaleAC2AAC4A

Manufacturing and finishing

CapabilityAC2AAC4A
Default condition——
Relative cost$$ Standard$$ Standard
Min. machined wall——
Best machined surface——

Both take the same 4 finishes: Electroless Nickel (EN), Epoxy Coating, Gold Plating, Silver Plating.

AC2A vs AC4A — frequently asked

Is AC4A stronger than AC2A?

Yes. AC4A has a typical yield strength of 200 MPa (29 ksi) against 170 MPa (24.7 ksi) for AC2A — about 18% more. Tensile strength is 260 MPa (37.7 ksi) vs 250 MPa (36.3 ksi).

Which is cheaper, AC2A or AC4A?

Both sit in the same relative cost tier ($$, standard); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which is easier to machine, AC2A or AC4A?

AC2A. Its machinability rates very good (72/100) against fair (50/100) for AC4A; for welding the order is AC4A first (good, 65/100) then AC2A (fair, 35/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in AC2A and AC4A 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.