Aluminum alloy sheet having excellent ridging resistance and hem bendability and production method for same

Abstract

The present disclosure relates to an aluminum alloy sheet having excellent ridging resistance and excellent hem bendability. The aluminum alloy sheet is an aluminum alloy rolled material for molding. The aluminum alloy rolled material includes an aluminum alloy that includes predetermined amounts of Mg, Si, and Mn and satisfies a condition of 0.005≤Mn+Cr≤0.080 mass %. In the aluminum alloy sheet, the position of a middle (t/2) of a sheet thickness is regarded as a center, the crystal particle diameter d1 of an L-LT plane in a sheet thickness in a range of ±(t/8) from the center is 30 to 80 μm, the crystal particle diameter d2 of an L-ST plane in the entire sheet thickness is 60 μm or less, and the cube orientation area rate C of a crystal orientation on a sheet surface is 10% or more.

1 . An aluminum alloy sheet with excellent ridging resistance and excellent hem bendability, the aluminum alloy sheet comprising:
 an aluminum alloy including 0.20 to 1.50 mass % Mg, 0.30 to 2.00 mass % Si, and one or two of 0.005 to 0.080 mass % Mn and 0.005 to 0.080 mass % Cr, satisfying 0.005 mass %≤Mn+Cr≤0.080 mass %, and comprising balance Al and inevitable impurities,   wherein   the aluminum alloy sheet has a sheet thickness t,   a position of a middle (t/2) of the sheet thickness is regarded as a center, and a crystal particle diameter d 1  of an L-LT plane in a sheet thickness in a range of ±(t/8) from the center is 30 to 80 μm,   a crystal particle diameter d 2  of an L-ST plane in the entire sheet thickness is 60 μm or less, and   a cube orientation area rate C of a crystal orientation on a sheet surface is 10% or more.   
     
     
         2 . The aluminum alloy sheet with excellent ridging resistance and excellent hem bendability according to  claim 1 ,
 wherein the aluminum alloy further including one or more of 0.01 to 0.40 mass % Zr, 0.03 to 1.00 mass % Fe, 0.005 to 0.300 mass % Ti, and 0.03 to 2.50 mass % Zn, and includes Cu restricted to 1.50 mass % or less.   
     
     
         3 . A method for producing the aluminum alloy sheet with excellent ridging resistance and excellent hem bendability according to  claim 1 , the method comprising:
 a casting step of casting the aluminum alloy; a hot-rolling step of hot-rolling an ingot to form a hot-rolled sheet; a cold-rolling step of cold-rolling the hot-rolled sheet without subjected the hot-rolled sheet to intermediate annealing, to form a cold-rolled sheet; and a solution treatment step of performing solution treatment of the cold-rolled sheet,   wherein in the hot-rolling step, a hot-rolling start temperature is set at 300 to 450° C., and a hot-rolling end temperature is set at 200 to 450° C.;   in the cold-rolling step, the cold-rolled sheet having a final sheet thickness is formed at a rolling reduction of 50.0% or more; and   in the solution treatment step, the solution treatment of the cold-rolled sheet is performed at a temperature of 480 to 590° C.   
     
     
         4 . The method for producing an aluminum alloy sheet with excellent ridging resistance and excellent hem bendability according to  claim 3 ,
 wherein the hot-rolling start temperature is set at 300 to 450° C., and the hot-rolling end temperature is set at 200 to 350° C.   
     
     
         5 . The method for producing an aluminum alloy sheet with excellent ridging resistance and excellent hem bendability according to  claim 3 ,
 wherein the hot-rolling start temperature is set at 350 to 450° C., and the hot-rolling end temperature is set at more than 350° C. and 450° C. or less.   
     
     
         6 . The method for producing an aluminum alloy sheet with excellent ridging resistance and excellent hem bendability according to  claim 3 , the method further comprising a homogenization treatment step of performing homogenization treatment of the ingot at a temperature of 480 to 590° C. for 0.5 to 24 hours between the casting step and the hot-rolling step.