Aluminum alloy material and method for manufacturing same

Abstract

An aluminum alloy material having a base material formed from an aluminum alloy, and a chemical treatment film on the surface of the base material. In a cathode polarization curve obtained by measuring the aluminum alloy material at a sweeping speed of 20 mV/min by using a saturated KCl silver-silver chloride electrode as a reference electrode in a 5 wt % NaCl static aqueous solution at a temperature of 25° C. and a pH of 5.5, the electrode potential at which the absoute value of the current density reaches 10 μA/cm2 is −1350 to −1150 mV.

1 . An aluminum alloy material, comprising: a base material made of an aluminum alloy; and a chemical conversion film on a surface of the base material, wherein
 in a cathodic polarization curve measured on the aluminum alloy material in a 5 wt % NaCl static aqueous solution at 25° C. having a pH of 5.5 with a saturated KCl silver-silver chloride electrode as a reference electrode at a sweep rate of 20 mV/min, an electrode potential at which an absolute value of a current density reaches 10 μA/cm 2  is −1350 mV to −1150 mV.   
     
     
         2 . The aluminum alloy material according to  claim 1 , wherein the base material is made of an aluminum alloy containing 0.3 to 5.0% by weight of Mg. 
     
     
         3 . The aluminum alloy material according to  claim 1 , wherein
 the chemical conversion film contains a Ti compound and a Zr compound,   the Ti compound is at least one selected from the group consisting of Ti oxide and Ti hydroxide,   the Zr compound is at least one selected from the group consisting of Zr oxide and Zr hydroxide, and   a total amount of the Ti compound and the Zr compound in the chemical conversion film is 2 to 29 mg/m 2  in terms of metal element amount.   
     
     
         4 . A method of manufacturing an aluminum alloy material in which, in a cathodic polarization curve measured in a 5 wt % NaCl static aqueous solution at 25° C. having a pH of 5.5 with a saturated KCl silver-silver chloride electrode as a reference electrode at a sweep rate of 20 mV/min, an electrode potential at which an absolute value of a current density reaches 10 μA/cm 2  is −1350 mV to −1150 my, the method comprising:
 performing acid etching on a base material made of an aluminum alloy containing Mg; and 
 applying chemical conversion treatment to a surface of the base material after the acid etching to form a chemical conversion film, wherein 
 an etching amount of the base material in performing acid etching [E: (mg/m 2 )] with respect to a Mg amount in the base material [M (wt %)] satisfies a relationship of 10 M≤E≤200 M, 
 
     
     
         5 . The method of manufacturing an aluminum alloy material according to  claim 4 , wherein in forming a chemical conversion film, the chemical conversion treatment is applied by using a treatment liquid containing a fluorinated titanium compound and a fluorinated zirconium compound such that a total mass concentration of the fluorinated titanium compound and the fluorinated zirconium compound in the treatment liquid [C (ppm, in terms of metal element amount)] and a treating time [t (seconds)] satisfy 50≤C×t≤1500. 
     
     
         6 . The aluminum alloy material according to  claim 2 , wherein
 the chemical conversion film contains a Ti compound and a Zr compound,   the Ti compound is at least one selected from the group consisting of Ti oxide and Ti hydroxide,   the Zr compound is at least one selected from the group consisting of Zr oxide and Zr hydroxide, and   a total amount of the Ti compound and the Zr compound in the chemical conversion film is 2 to 29 mg/m 2  in terms of metal element amount.