Abstract
The effect of ball burnishing on the rotating beam fatigue strength of age-hardened 6082-T4 and 7075-T73 aluminum has been investigated. Deep rolled specimens were cyclically deformed at room temperature using push-pull stress controlled fatigue and compared to the electrically polished condition as a reference, Also Shot peened condition give better results compared to electrically polish. Optimization curve was produced for both SP and BB conditions, due to this optimization shot peened with Almen intensity of 0.2 mmA for both alloys was used. For ball burnishing (deep rolling) 40 bars was used for 6082-T4 and 75 bars for 7075-T73 by deep rolling tool HG13. The observed improvements were from about 45% for Al 6082-T4 while it was the double for Al 7075-T73 compared to electrically polish, while the improvement of fatigue for BB condition compared to SP was 5% for AI 6082-T4 and 28 % for Al 7075-T73. Data analysis shows that the fatigue behavior in these alloys affected by surface treatment. It was found that deep rolling can dramatically enhance the fatigue behavior of aluminum alloys as compared to the shot peening and polished condition due to near surface compressive residual stresses as well as work hardening states and increased hardness induced by mechanical surface treatment (deep rolling).