4145 (BAlSi-3) Aluminum
4145 aluminum is a 4000-series aluminum alloy. The main alloying addition is silicon. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 4145 is the Aluminum Association (AA) designation for this material. In European standards, it will be given as EN AW-4145. BAlSi-3 is the AWS designation. Additionally, the UNS number is A94145.
It originally received its standard designation in 1957.
It has the lowest electrical conductivity and the lowest thermal conductivity among 4000-series alloys.
The graph bars on the material properties cards below compare 4145 aluminum to: 4000-series alloys (top), all aluminum alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
73 GPa 11 x 106 psi
Elongation at Break
2.2 %
Fatigue Strength
48 MPa 6.9 x 103 psi
Poisson's Ratio
0.33
Shear Modulus
28 GPa 4.0 x 106 psi
Shear Strength
69 MPa 9.9 x 103 psi
Tensile Strength: Ultimate (UTS)
120 MPa 17 x 103 psi
Tensile Strength: Yield (Proof)
68 MPa 9.8 x 103 psi
Thermal Properties
Brazing Temperature
570 to 600 °C 1060 to 1120 °F
Latent Heat of Fusion
540 J/g
Maximum Temperature: Mechanical
160 °C 330 °F
Melting Completion (Liquidus)
590 °C 1090 °F
Melting Onset (Solidus)
520 °C 970 °F
Specific Heat Capacity
880 J/kg-K 0.21 BTU/lb-°F
Thermal Conductivity
100 W/m-K 61 BTU/h-ft-°F
Thermal Expansion
21 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
26 % IACS
Electrical Conductivity: Equal Weight (Specific)
84 % IACS
Otherwise Unclassified Properties
Base Metal Price
10 % relative
Density
2.8 g/cm3 180 lb/ft3
Embodied Carbon
7.6 kg CO2/kg material
Embodied Energy
140 MJ/kg 61 x 103 BTU/lb
Embodied Water
1040 L/kg 120 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
2.3 MJ/m3
Resilience: Unit (Modulus of Resilience)
31 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
50 points
Strength to Weight: Axial
12 points
Strength to Weight: Bending
19 points
Thermal Diffusivity
42 mm2/s
Thermal Shock Resistance
5.5 points
Alloy Composition
Among wrought aluminum alloys, the composition of 4145 aluminum is notable for containing comparatively high amounts of silicon (Si) and copper (Cu). Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy. Copper is used to improve strength. This comes at the cost of a decrease in corrosion resistance and weldability.
| Al | 83 to 87.4 | |
| Si | 9.3 to 10.7 | |
| Cu | 3.3 to 4.7 | |
| Fe | 0 to 0.8 | |
| Zn | 0 to 0.2 | |
| Mn | 0 to 0.15 | |
| Cr | 0 to 0.15 | |
| Mg | 0 to 0.15 | |
| res. | 0 to 0.15 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
AWS A5.8: Specification for Filler Metals for Brazing and Braze Welding
ASM Specialty Handbook: Aluminum and Aluminum Alloys, J. R. Davis (editor), 1993