EN AW-2007 | AlCu4PbMg | AA2007 Cracks due to cumulative and coarse precipitations
| Numeric designation | EN AW-2007 | AA2007 |
|---|---|
| Chemical designation | AlCu4PbMg |
| State | Cracks due to cumulative and coarse precipitations |
| Etching | 5 % NaOH |
In the components turned from extruded bar stock (semi-finished product), axial cracks occurred during mechanical processing. These follow the pronounced lines of intermetallic Al-Cu-Fe-Mn phases, some of which are still very coarse. In the comparative part of a good batch, the precipitations are more finely shattered and more evenly distributed. The composition of both batches is within specification, but the cracked sample contains slightly more Cu, Fe, Si and Mg and is also harder. The cause of damage is probably a too low degree of deformation during extrusion and/or too large segregations in the extrusion ingot.
