Residual Stress effect on Fatigue Behavior of 2024- Aluminum alloy

Abstract

In the present work the effect of residual stress on the fatigue behavior of 2024 Aluminum alloy was studied experimentally and numerically using finite element method with aid of ANSYS-11 software. All the test specimens treated by annealing before any process to remove the internal stresses due to cold work. Residual stresses were imparted to the fatigue tests specimens by heat treatment, pre-strain and welding. X-Ray diffraction was used to measure the residual stress. The heat treatment; done on the test specimens with different temperature of (420, 450, 480, and 510) oC. After heat treatment; alloy mechanical properties were improved. For the heat treated specimens as the temperature increased the compressive residual stress increased to (27.06, 41.43, 72.8 and 85.6) MPa. That leads to increase the endurance fatigue limit by (32.93%, 40.48%, 50.68% and 61.03%) respectively than other alloy as received. While in pre strain groups; the test specimens loaded to (265, 290, 315 and 340) MPa by a tension test machine. As the applied load series were increased the compressive residual stress increased to (16.51, 25.62, 51.54 and 62.44) MPa which improve the endurance fatigue limit by (7.68%, 16.19%, 24.98%, and 46.45%), respectively. An electrical arc and metal inert gas were used in welding series to weld the test specimens, that present a tensile residual stress of (76.93 and 72.66) MPa, which reduces the endurance fatigue limit by (23.45% and 16.08%), respectively. The numerical results present fatigue behavior, deflection and stress at any load, and show a reasonable agreement results with an experimental one.

Keywords

• residual stresses
• fatigue
• ray diffraction