Intergranular Corrosion Mechanism of Brazed Al-Mn-Cu-Si Alloy

Abstract:

This paper investigated the effect of Si addition on intergranular corrosion susceptibility for brazed Al–Mn–Cu alloy. Water-quenched samples have no intergranular corrosion (IGC) susceptibility, however, slowly cooled samples have IGC susceptibility. This implies that IGC susceptibility was caused by precipitation during cooling. In addition, IGC susceptibility depends on Si content. Low Si additive alloy has high IGC susceptibility. This is because the Mn/Cu depleted zone is formed near the grain boundary due to preferential precipitation of Mn-bearing compound and CuAl₂ on the grain boundary. Conversely, optimum Si addition inhibits IGC due to the absence of preferential precipitation on the grain boundary. The excess Si alloy has high IGC susceptibility as the Si depleted zone is formed around the grain boundary due to the preferential precipitation of coarse Si particles on the grain boundary.

• Periodical: Materials Science Forum (Volume 877)
• Pages: 492-497
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.877.492
• Online since: November 2016
• Authors: Michihide Yoshino*, Shohei Iwao, Masakazu Edo, Hajime Chiba
• Keywords: Al-Mn Alloy, Brazing, Grain Boundary Precipitation, Heat Exchanger, Intergranular Corrosion, Solute Depleted Zone

References

[1] K. Tohma, J. Japan Inst. Met. Mater. 46 (1982) 973-979.

[2] M. Kaifu, H. Fujimoto, M. Takemoto, Influence of Manganese Contents and Heat Treatments on Intergranular Corrosion of Al-Mn Alloys, J. Japan Inst. Light Met. 32 (1982) 135-142.

[3] M. Kaifu, H. Fujimoto, M. Takemoto, Proceedings of the japan institute of light metal, (1980) 137-138.