The main difficulty in welding aluminum bronze plates is the oxidation of aluminum, which produces a dense and refractory Al2O3 film covering the surface of the droplets and molten pools, which is prone to defects such as slag inclusions, pores and unfusion in the weld.
Removing aluminum oxide and preventing aluminum oxidation become the key to the success or failure of welding aluminum bronze. In addition, the single-phase aluminum bronze with w(Al)<7% has hot brittleness, which is easy to crack in the heat-affected zone and difficult to weld. Single-phase alloys and dual-phase alloys with w(A1) ≥ 7% can be welded with some crack prevention measures. Gas welding is generally not recommended because it is difficult to completely eliminate the harmful effects of aluminum oxides.
If gas welding must be used, the welding wire and welding groove must be thoroughly cleaned, and a flux containing chloride salt and fluoride salt must be used. Strictly adopt measures such as neutral flame. Electrode arc welding is generally used for welding repair of aluminum bronze forgings or castings.
Use ECuAl-c (ie T237) electrode. Except for thin parts (≤3mm), a V-shaped groove of 70° to 90° should be used; thin parts are often not preheated. For alloys with w(Al)<10%, the preheating and interlayer temperatures should generally not exceed 150°C. When welding aluminum bronze with aluminum content of 10% to 13%, the recommended preheating and interlayer temperature for thick workpieces are about 260 °C, and the weldment should be cooled quickly. Welding with DC reverse connection, short arc and narrow bead. During multi-layer welding, the slag must be thoroughly cleaned between layers.
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