Effect of Microstructure and Anodizing On the Fatigue Performance of a Large 2219 Aluminum Forging

Pressure testing of a thick section 2219 aluminum forging resulted in cracking at one of the internal bores.  An examination of the crack revealed that the part failed in fatigue.  Fatigue had occurred due to extensive attack at the surface from the anodizing treatment.  An investigation took place in order to improve the homogeneity and microstructure of the material in order to lessen the surface attack of the anodizing treatment.  This presentation will show the steps taken to improve the material microstructure and reduce the fatigue debit associated with the surface treatments.  Axial fatigue testing was carried out in order to validate the material properties in line with the new heat treatment steps.  Test data for the thick section forging will be shared.