Deep drawing of process optimized blanks

The forming properties of aluminium alloys are comparatively low, and consequently the forming processes turn out to be difficult. To reduce these problems, a process that optimizes the drawability of aluminium alloys was developed. By a laser-induced pre-treatment, the material properties are locally changed so that influencing of the material flow is possible. For hardenable aluminium alloys the laser-induced heat treatment results in a dissolution of the precipitations, i.e. a conversion from the stable naturally aged T4 to the unstable solution heat treated W-condition of the material. This leads to a reduction of the local flow stress. Using this softening of the material in the outer zone of deep drawing blanks, an increase of the limiting drawing ratio from 2.1 to 2.6 is possible for the alloy AA 6181 A. One interesting feature of this method is that after 1000 h at room temperature, the microstructural changes are recovered. For use in automotive lightweight constructions, this means weight optimized car body panels that can be produced in fewer process steps. (C) 2001 Elsevier Science B.V. All rights reserved.