How to weld the lead wire of iron-chromium-aluminum heating wire

Iron-chromium-aluminum heating wires, especially under high-temperature conditions, rapidly develop a dense, high-melting-point aluminum oxide (Al₂O₃) protective film on their surface. While this film protects them from oxidation at high temperatures, it also presents a significant obstacle during soldering. It significantly hinders solder wetting and spreading, rendering conventional soldering impossible. Furthermore, this alloy is prone to coarse grains and brittleness during high-temperature soldering. Even the slightest mistake can cause fractures in the material surrounding the solder joint, leading to component failure.

Mr. Li, a senior engineer at a well-known home appliance company, admitted, "In the past, connecting iron-chromium-aluminum wires mostly relied on mechanical crimping or wrapping followed by coating with high-temperature coatings. This method results in high contact resistance and is prone to heat and oxidation, making it the weakest link in the entire heating component and the primary cause of many premature product failures."

New Technology Breakthrough: A Two-Pronged Approach of Precision Processing and Specialized Materials

To address this industry pain point, materials experts and welding engineers have, after years of research, developed and promoted a proven, high-reliability soldering solution. The core of this solution lies in combining film removal with protection.

Physical film removal is the critical first step: Before soldering, the oxide film on the surface of the solder joint must be thoroughly removed mechanically using methods such as sandblasting, sandpaper polishing, or wire brushing. This process must be performed quickly to prevent the rapid formation of a new oxide film.

Special brazing materials offer a unique advantage: Conventional solder is ineffective against this problem, requiring specialized high-temperature brazing filler metals. Currently, the industry generally recommends using silver-based filler metals with high silver content and good fluidity (such as the Ag-Cu series), combined with a potent fluoride-based flux. This flux effectively dissolves and destroys residual aluminum oxide film, creating a secure bond between the filler metal and the substrate.

Process Selection: The Art of Speed ​​and Heat:

Flame brazing: Flexible operation requires skilled welders. A neutral or slightly carburizing flame is used, ensuring rapid, concentrated heating to avoid overheating the entire heating wire.

Resistance welding (butt welding): This is an efficient and ideal option for high-volume production. A high, instantaneous current generates intense heat at the contact point, creating a molten connection. The entire process is completed within milliseconds, significantly minimizing thermal impact on the parent material.

TiG welding (TIG): TIG welding can be used for extremely demanding applications. It requires high-current, fast welding techniques, and adequate argon gas protection of the weld point.
The maturity and widespread adoption of this welding technology has significantly improved the overall quality and stability of iron-chromium-aluminum heating elements. It has reduced after-sales issues and safety risks caused by failed joints, enhancing the market competitiveness of downstream manufacturers. In the future, with the further introduction of automated welding equipment, the efficiency and consistency of this process will be further enhanced, driving the entire electric heating industry towards greater efficiency and reliability.

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