アルミニウム合金ブレージングシートの耐食性に及ぼす熱処理の影響

抄録

SWAAT for 20 days has been carried out on brazing sheets of 1 mm thickness to estimate outside corrosion resistance on the material for aluminum heat exchanger applied at higher temperature. Maximum corrosion depth after the test decreased in brazing sheets both of Al–1%Mn alloy core and of Al–1%Mn–0.5%Si alloy core clad with Al–Si alloy filler while it increased in that of Al–1%Mn–0.5%Si–0.5%Cu alloy core, with increase of heat treatment time at 200°C after brazing. Marked intergranular corrosion in the core was observed in the latter alloy. On the other hand, general corrosion was observed in brazing sheets clad with filler alloy containing Zn, and the attack stopped at near interface between filler and core, independent of core alloys and of heat treatment time. Corrosion characteristics and attack depth on the sheets were discussed in terms of electrochemical properties of filler and core alloys.