Patent attributes
Aluminum alloy strips less than 0.3 mm thick for making heat exchangers, containing, in wt. %: Si<1.0, Fe<1.0, Cu<0.8, Mg<1.0, Mn≦1.8, Zn<2.0, In<0.2, Sn<0.2, Bi<0.2, Ti<0.2, Cr<0.25, Zr<0.25, Si+Fe+Mn+Mg>0.8, other elements <0.05, each and <0.15 in total. The strips have between the surface and half the thickness a difference of corrosion potential, measured relative to a saturated calomel electrode in accordance with the ASTM G69 standard, of at least 10 mV. The invention also concerns a method for making such strips by continuous casting in conditions promoting formation of segregations in the strip core, optionally hot rolling, cold rolling optionally with one or several intermediate or final annealing(s) of 1 to 20 hours at a temperature between 200 and 450° C. The fins or separators made from the inventive strips have enhanced resistance to perforating corrosion.
