Pure copper plates were welded with pure copper and Cu-Ti alloy electrode wires using Ar-N//2 gas shieldings. The effects of welding conditions, nitrogen percentage in the shielding gas and titanium content of the electrode wire on porosity and microstructure of the weld metal were systematically examined. When pure copper electrode wire is used, a high welding current leads to good surface appearance and deep penetration, but high porosity in the weld metal. The porosity of weld metal increases with N//2% in the shielding gas. This tendency becomes very weak when the electrode contains titanium. The nitrogen content of weld metal increases with N//2% in the shielding gas. This tendency becomes more remarkable with an increase in titanium content of electrode wire. When the electrode wire contains titanium and the shielding gas contains nitrogen, a secondary phase emerges in the weld metal. The fractional area of the secondary phase in the weld metal increases with N//2% in the shielding gas and titanium content of the electrode wire. The electron diffraction patterns of the secondary phase are in good agreement with those of TiN. The temperature of molten copper pool during arc welding was measured, and the formation of TiN was discussed with thermodynamic data.
|Number of pages||8|
|Journal||Transactions of the Japan Welding Society|
|Publication status||Published - 1987 Oct 1|
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