Braze Welding Brass is a low-temperature metal joining technology that uses copper-based alloys (such as brass, phosphor copper, etc.) as filler materials. It achieves metallurgical bonding of dissimilar metals by melting filler metals (melting point is usually below 450°C). The process uses capillary action to allow liquid filler metal to penetrate into the joint gap and form a high-strength weld after cooling.
| BrazingAlloys | AWS | Chemical Composition（%） | Solidus | Liquidus | Main Uses | |||||||
| Ag | Cu | Zn | Sn | Si | Other | F | ℃ | F | ℃ | |||
| BCu | BCu-1 | / | 100 | / | / | / | / | 1981 | 1082 | 1981 | 1082 | Suitable for furnace brazing of steel, stainless steel and nickel-based alloys. |
| BCu58Zn | / | / | 58 | / | 38 | / | Mn：4 | 1616 | 880 | 1668 | 909 | Mainly used for brazing of hard alloy cutter. |
| BCu60Zn | / | / | 60 | / | 39 | 1 | Si：0.25 | 1634 | 890 | 1661 | 905 | Mainly used for brazing ferrous metals, nickel-based alloys and Cu-Ni alloys; it has good fluidity. |
| BCu58ZnFe | BCuZn-C | / | 58 | / | 40.2 | 1 | Fe：0.8 | 1670 | 910 | 1749 | 954 | |
| BCu48ZnNi | BCuZn-D | / | 48 | / | 41.8 | / | Ni：1 Si：0.2 | 1720 | 938 | 1799 | 982 | |
1. Low-temperature welding characteristics
Melting point range: The melting point of brass brazing material is 850-950°C, which is much lower than the traditional fusion welding temperature (such as steel melting point above 1400°C), which can reduce the risk of deformation in the heat affected zone (HAZ).
Typical process parameters:
Heating rate: 10-15℃/min (avoid local overheating)
Hot-keeping temperature: 900-960℃ (ensure full wetting of filler metal)
Cooling rate: Cool to 300℃ with the furnace and then air cool (to prevent stress cracking)
2. Material compatibility and strength
Filler metal type:
Ordinary brass brazing filler metal (Cu-Zn alloy): suitable for conventional connection of carbon steel, stainless steel and copper alloy, with tensile strength ≥300MPa.
Special brass brazing filler metal (adding elements such as Sn, Mn, Ni): For example, brass brazing filler metal containing 1% tin can reduce the melting point to 800℃ and improve the corrosion resistance of the weld (salt spray test ≥500 hours).
Joint strength: The strength of a typical brazed joint can reach 80%-90% of the base material, meeting the ASTM B765 standard.
3. Process accuracy and efficiency
Weld seam control: minimum weld seam width: 0.05mm (suitable for electronic component lead welding), maximum welding area: 78.87m² (such as large heat exchanger tube sheet connection)
Production efficiency: single piece welding cycle: 1-2 hours (including preheating, insulation, cooling)
Automation compatibility: support robot automatic feeding and temperature monitoring (such as KUKA industrial robot integration solution).
1. Automobile manufacturing field
Application scenarios:
Radiator copper tube and aluminum water tank welding: use manganese-containing brass brazing material (such as AWS BCuZn-C) to solve the cracking problem caused by the difference in thermal expansion coefficients of aluminum-copper dissimilar metals, and the joint leakage rate is ≤0.1%.
Turbocharger housing repair: silver-based brazing material (melting point 600-800℃) is used to repair nickel-based alloy cracks, the weld hardness reaches HV200-250, and the high temperature oxidation resistance is improved by 30%.
Typical customer cases:
A German automaker uses an average of 200-300 brazing joints per vehicle, reducing production costs by 15% and increasing product qualification rate to 99.2%.
2. Aerospace and precision manufacturing
Application scenarios:
Turbine blade honeycomb structure connection: Use silver-copper brazing material (Ag-Cu-Zn) to complete the welding of titanium alloy and nickel-based alloy at 920°C, and the fatigue life of the weld reaches 10⁷ cycles.
Electronic component lead welding: Use 0.1mm diameter brass welding wire, combined with a vacuum brazing furnace (residual oxygen content ≤5ppm), to achieve oxygen-free welding of micro components.
Technical advantages:
Porosity of weld ≤0.5% (X-ray inspection standard)
Conductivity of joint ≥90% IACS (International Annealed Copper Standard)
3. Industrial equipment and energy fields
Application scenarios:
Nuclear power plant steam generator tube sheet welding: Use nickel-based brazing filler metal (such as BNi-2) to complete the welding of Inconel 600 alloy and low carbon steel at 1050℃, and the radiation dose of the weld is ≥10¹⁸ neutrons/cm².
Corrosion protection of stainless steel bellows on offshore platforms: Adopt 316L stainless steel substrate + brass brazing filler metal composite structure, and the salt spray corrosion resistance time is extended to 2000 hours (ASTM B117 standard).
1. Post-weld treatment
Deoxidation layer: Use QJ-302 copper flux (containing boric acid and borax) to remove the oxide film on the weld surface, the operating temperature is ≥200℃, and the time is 3-5 minutes.
Pickling and passivation: Use nitric acid-hydrofluoric acid mixture (volume ratio 5:1) to pickle the stainless steel base weld for ≤10 minutes to avoid pitting.
2. Long-term maintenance
Anti-corrosion coating: It is recommended to use epoxy resin coating (thickness ≥50μm), which improves salt spray resistance by 50%.
Regular inspection: Perform ultrasonic flaw detection (UT) or eddy current testing (ET) every 6 months to ensure that there is no crack expansion in the weld.
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