ALUMINUM ALLOY MATERIAL FOR HEAT EXCHANGER HAVING EXCELLENT CORROSION RESISTANCE

PURPOSE:To obtain an Al alloy material having excellent strength and corrosion resistance by providing the surface layer part of an Al alloy material contg. specific amounts of Cu with a diffusion layer whose Cu concentration is gradually decreased by the difference of specific concentration from its inner part toward the surface into the specific thickness. CONSTITUTION:In the surface layer part of the Al alloy material contg. 0.2-1.0wt.% Cu and furthermore contg. at need one or two kinds between 0.6-1.4% Mn and 0.1-0.8% Mg, the diffusion layer having 40-300mum thickness whose Cu concentration is gradually decreased from its inner part toward the surface and in which the difference of concentration between its inner part and surface is regulated to 0.15-0.6% is provided. Said diffusion layer formed by cladding or casting the Al alloy such as pure Al or Al-Mn series, etc., into the core of the above-mentioned Al-Cu alloy and thereafter subjecting it to a diffusion treatment. By said diffusion layer, the surface layer part having a sacrificial anodic effect is formed to improve the corrosion resistance of the Al alloy material.