Manufacturing method for al-mg-si aluminum alloy sheets with excellent bake hardenability

Abstract

[Objectives] Strengthening, cost reduction, and improvement of press formability and bake hardenability of aluminum alloy sheets. [Means for achieving objectives] A manufacturing method for Al—Mg—Si aluminum alloy sheet with excellent bake hardenability, characterized by twin belt casting a molten Al—Mg—Si aluminum alloy containing Mg: 0.3-1.0 wt %, Si: 0.3-1.5 wt %, Cu: 1.0 wt % or below (including 0%), and Fe: 1.2 wt % or below (including 0%), and containing Mn: 0.1-0.7 wt % and/or Cr: 0.1-0.3% according to need, and the remnant being Al at an average cooling rate of 20 degrees C. or above, and at that time, making the temperature of the ingot as it comes out of the casting machine 250 degrees C. or below, and then rolling to the final sheet thickness by cold rolling only and without homogenization or hot rolling, and solution treatment being done in a continuous annealing furnace.

1 . A manufacturing method for Al—Mg—Si aluminum alloy sheets with excellent bake hardenability, characterized in that 
 (a) a molten Al—Mg—Si aluminum alloy comprising Mg: 0.3-1.0 wt %, Si: 0.3-1.5 wt %, Cu: 1.0 wt % or below (including 0%), Fe: 1.2 wt % or below (including 0%), and according to need, containing Mn: 0.1-0.7 wt % and/or Cr: 0.1-0.3%, and the remnant being Al is twin belt cast at an average cooling rate of 20 degrees C. per second or above at the time of solidification,    (b) at this time, the temperature of the ingot coming out of the casting machine is 250 degrees C. or below,    (c) then, rolling is done to the final sheet thickness by only cold rolling, without homogenization or hot rolling,    (d) and solution treatment is done in a continuous annealing furnace.    
   
   
       2 . A manufacturing method for Al—Mg—Si aluminum alloy sheet with excellent bake hardenability, characterized in that 
 (a) a molten Al—Mg—Si aluminum alloy containing Mg: 0.3-1.0 wt %, Si: 0.3-1.5 wt %, Cu: 1.0 wt % or below (including 0%), Fe: 1.2 wt % or below (including 0%), and according to need, containing Mn: 0.1-0.7 wt % and/or Cr: 0.1-0.3%, and the remnant being Al is twin belt cast at an average cooling rate of 20 degrees C. per second or above at the time of solidification,    (b) at this time, the ingot is cooled so that the ingot temperature is 250 degrees C. or below within 2 minutes from pouring the molten metal into the casting machine,    (c) then, rolling is done to the final sheet thickness by only cold rolling, without homogenization or hot rolling,    (d) and solution treatment is done in a continuous annealing furnace.