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.