Brazing aluminum sheet coil strips 3003 clad 4045 for heat exchangers typically feature a three-layer composite structure of 4045-3003-4045. These high-performance brazing materials are specifically designed for heat exchange applications, leveraging the complementary advantages of the two aluminum alloys to play a crucial role in various heat exchange devices.

Structure of 4045/3003/4045 aluminum brazing sheet coil strip:
This aluminum strip employs a "surface layer-core layer" composite design. The core layer is 3003 aluminum alloy, an Al-Mn alloy with a manganese content of 1.0%-1.5%. The upper and lower surface layers are 4045 aluminum alloy, an Al-Si alloy with a silicon content of 4.0%-6.0%. The common total thickness range is wide, including thin specifications like 0.10-0.15mm suitable for precision fins, and specifications like 0.8-1.2mm suitable for large heat exchange components. The coverage rate is typically controlled between 8% and 12%, and thickness and width can be customized upon request.

Material properties of aluminum 3003 mod +A4045 brazing sheet coil strip:
- 3003 aluminum alloy (core layer)
Composition: Mn 1.0-1.5%, Fe≤0.7%, Si≤0.3%, Cu≤0.05-0.2%, balance Al.
Properties:
Strength and Formability: Tensile strength 120-160MPa, elongation ≥25%, suitable for complex forming processes such as deep drawing and bending, meeting the design requirements of evaporator flow channels.
Corrosion Resistance: Mn forms a dense oxide film, providing superior corrosion resistance to ordinary aluminum in humid or chlorine-containing environments, extending the service life of the evaporator.
Application Scenarios: Widely used in automotive and residential air conditioning evaporator cores, providing structural support and heat dissipation.

- 4045 aluminum alloy (clad layer)
Composition: Si 9.5-12%, Fe≤0.8%, Cu≤0.3%, Mn≤0.5%, balance Al.
Properties: Low Melting Point Brazing: Melting point approximately 577℃ (more than 80℃ lower than 3003), melts rapidly at a brazing temperature of 600℃, filling the core layer gaps and forming a strong metallurgical bond.
Flowability and wettability: High Si content reduces melt viscosity, improves flowability, and ensures a dense, defect-free brazed seam.
Application scenarios: Used as a brazing layer covering the surface of the 3003 core layer to achieve a reliable connection between the evaporator fins and piping.

Performance advantages of brazing aluminum sheet coil strip 3003 clad 4045:
- Bragging compatibility:
4045 aluminum alloy has a melting point of approximately 600-650℃, significantly lower than 3003 aluminum alloy. At brazing temperatures, it melts rapidly to form brazing filler metal, filling the weld gap with its excellent fluidity. The core 3003 remains solid, ensuring structural stability. The welded joint is free of porosity and cracks, with a bright surface and uniform rounded corners.
- Balancing corrosion resistance and mechanical properties:
The core 3003 aluminum alloy exhibits strong resistance to corrosion from the atmosphere, fresh water, and weak acids and alkalis, resisting the erosion of heat exchange media and extending equipment lifespan. Simultaneously, metallurgical bonding is achieved through rolling composite or casting-rolling processes, resulting in an interface diffusion layer of approximately 15 micrometers. The overall tensile strength reaches 100-150 MPa, combining strength and ductility, with minimal deformation and easy forming during processing.
- Lightweight and energy-saving:
With a density of 2.7 g/cm³, it is 63% lighter than copper, contributing to a 15-20% weight reduction in new energy vehicles and increasing driving range. The thermal conductivity is 160 W/(m·K), which is 53% of that of copper, but equivalent heat dissipation performance can be achieved through optimized flow channel design.
- Cost-effectiveness:
Material costs are 60-70% lower than copper, processing fees increase by about 15%, resulting in an overall cost reduction of 40-50%.
After mass production, the 3003/4045 aluminum composite brazing strip offers significant cost-effectiveness.

Key technical parameters of 4045/3003/4045 brazing aluminum sheet coil strip are:
Coverage Rate: 8% - 12%
Mechanical Properties: Yield strength ≥ 45MPa, elongation minimum 27%
Heat Treatment States: Commonly O state, H14, etc. Hardness in H14 state is approximately 70-90HB, suitable for various processing needs
Bragging Compatibility: 4045's low melting point characteristics make it suitable for heat exchanger brazing processes, ensuring weld strength.

Core applications in the heat exchanger field:
- Automotive heat exchange systems:
It is a core material for water-cooled plates for new energy vehicle power batteries, automotive radiator fins, air conditioning evaporators, and water tank baffles. It reduces vehicle energy consumption through lightweight characteristics and ensures the heat exchange efficiency of the cooling system through high-efficiency brazing performance, stabilizing the operating temperature of the power battery and engine.
- Industrial and general refrigeration equipment:
Suitable for industrial chillers, heat exchange cores of central air conditioning systems, condensing/heat dissipation equipment, etc. The corrosion resistance of 3003 can withstand long-term corrosion from refrigerants, while the brazing advantage of 4045 ensures the sealing of equipment assembly and reduces the risk of leakage.
- Specialty heat exchange components:
Can be used in small heat exchangers in marine and chemical industries, dealing with marine chloride ion or weakly corrosive chemical environments. However, attention must be paid to structural design to avoid galvanic corrosion.