Ultra sagging and melting resistant fin material with very high strength

Abstract

Method for producing AIMn strip or sheet for making components by brazing and products obtained by said method, in particular fin materials of thin gauge used in heat exchangers. Rolling slabs are produced from a melt with <0.3% Si, ≦0.5% Fe, ≦0.3% Cu, 1.0-2.0% Mn, ≦0.5% Mg, ≦4.0% Zn, ≦0.5% Ni, ≦0.3% each of group IVb, Vb, or Vib elements, and unavoidable impurity elements, as well as aluminum that, prior to hot rolling, are preheated at <550° C. to control the number and size of dispersoid particles, hot rolled into a hot strip, cold rolled into a strip with total reduction of at least 90%, and heat treated to obtain a 0.2% proof stress value that is 50-90% of its proof stress value in the as cold rolled condition and in a range between 100 and 200 MPa. The strip may alternatively be produced by twin-roll strip casting.