Hot forming aluminum alloy plate and production method therefor

Abstract

The present invention provides an Al—Mg—Si-based hot forming aluminum alloy plate which has not only high age-hardening property but also a high m value in a high strain rate range and excellent surface properties after forming and which is suitable for hot forming. The hot forming aluminum alloy plate comprises an aluminum alloy comprising 0.3 to 1.8 mass % Mg, 0.6 to 2.0 mass % Si and 0.04 to 0.20 mass % Fe. In the aluminum alloy, Mn content is restricted to 0.030 mass % or less, and Cr content is restricted to 0.030 mass % or less, and a balance comprises Al and unavoidable impurities. The hot forming aluminum alloy plate has an electrical conductivity of 60% or less according to IACS %. A production method of the hot forming aluminum alloy plate is also provided.

1 . A hot forming aluminum alloy plate comprising an aluminum alloy,
 wherein the aluminum alloy comprises 0.3 to 1.8 mass % Mg, 0.6 to 2.0 mass % Si and 0.04 to 0.20 mass % Fe, Mn content is restricted to 0.030 mass % or less, Cr content is restricted to 0.030 mass % or less, and a balance comprises Al and unavoidable impurities, and   the hot forming aluminum alloy plate has an electrical conductivity of 60% or less according to IACS %.   
     
     
         2 . The hot forming aluminum alloy plate according to  claim 1 , wherein the aluminum alloy further comprises 0.2 to 1.0 mass % Cu. 
     
     
         3 . The hot forming aluminum alloy plate according to  claim 1 , wherein the hot forming aluminum alloy plate is used for blow molding. 
     
     
         4 . A method for producing the hot forming aluminum alloy plate according to  claim 1 , the method comprising:
 a casting step for casting a molten metal of the aluminum alloy;   a homogenization step for homogenizing the cast slab;   a hot rolling step for hot rolling the homogenized slab; and   a cold rolling step for cold rolling the hot-rolled plate:   wherein in the homogenization step, the slab is heated and held at a temperature which is 500° C. or higher and lower than the melting point of the aluminum alloy for 1 to 12 hours, and the cooling rate from the completion of heating and holding to 300° C. is 50° C./hour or more;   a temperature of the rolled plate during hot rolling is 250 to 450° C. in the hot rolling step; and   a reduction ratio in the cold rolling step is 50% or more.   
     
     
         5 . A method for producing the hot forming aluminum alloy plate according to  claim 1 , the method comprising:
 a casting step for casting a molten metal of the aluminum alloy;   a homogenization step for homogenizing the cast slab;   a hot rolling step for hot rolling the homogenized slab;   a cold rolling step for cold rolling the hot-rolled plate; and   an annealing step for annealing the rolled plate:   wherein in the homogenization step, the slab is heated and held at a temperature which is 500° C. or higher and lower than the melting point of the aluminum alloy for 1 to 12 hours, and the cooling rate from the completion of heating and holding to 300° C. is 50° C./hour or more;   the temperature of the rolled plate during hot rolling is 250 to 450° C. in the hot rolling step;   the reduction ratio in the cold rolling step is 50% or more; and   in the annealing step, the rolled plate is annealed at a temperature of 500 to 580° C. during the cold rolling step, the heating rate to the annealing temperature is 5° C./second or more, and the cooling rate after annealing is 100° C./second or more.   
     
     
         6 . The method for producing the hot forming aluminum alloy plate according to  claim 4 , wherein the reduction ratio in the cold rolling step is 80% or more. 
     
     
         7 . The method for producing the hot forming aluminum alloy plate according to  claim 4 , wherein a DC casting process in which the cooling rate is 50° C./minute or more is used in the casting step.