Influences of manganese contents and brazing conditions on brazeability and shape retainability of Al–Si based alloy sheets for brazing

In Al–Si based alloy sheets for brazing, the balance between brazeability and shape retainability is important. This study shows the influence of Mn contents and brazing conditions on the brazeability and the shape retainability during brazing. The brazeability was evaluated using a test piece called “reverse T shape” and the shape retainability was evaluated by a sagging test. The results showed that the brazeability was influenced by the equilibrium liquid phase fraction during brazing. Then, Mn contents and brazing conditions had little influence on the brazeability because these factors did not change the liquid phase fraction significantly. The results also showed that the shape retainability during brazing was much influenced by the addition of Mn. Due to the addition of Mn, many particles consisting of Al, Si, Mn and Fe were formed during sheet-manufacturing process and made grains coarser when recrystallization occur during brazing. Therefore, the addition of Mn was effective for improving the balance between the brazeability and the shape retainability.