1988 年 38 巻 1 号 p. 47-53
Aging behavior and electrochemical polarization characteristics of Al-Zn-Mg alloys sheets and castings containing Cu, Cr, Si and Ti up to 0.1 at% were investigated. The HV values of sheets are 110-120 which are higher 20-30 than those of castings. Grain size of sheets decrease with increases of element contents, especially in the addition of Ti. Pitting potential in 0.5N NaCl solution changes toward to noble value with increases of additional contents, especially in the sheets contained Cu. Passivation current density reduces with increases of additional contents. The pitting potential changes toward to noble value and the passivation current density reduces with increase of aging time, respectively. These phenomena are explained by correspondance of change of solute quantity of Zn and/or Mg on the surface.