The influence of welding on the low-cycle fatigue behaviors of Al-7017 weldments has been studied.
The specimens were welded by Gas Metal Arc Welding process, and four different specimens, such as base metal, weldment, the simulated HAZ (heat affected zone)-I and HAZ-II were investigated for the mechanical properties and microstructures.
The experimental result indicated that low-cycle fatigue life decreased from base metal, HAZ-II and HAZ-I to weldment in order. The break-point was observed in Manson-Coffin plot for the base metal, HAZ-I and HAZ-II specimens. We believed that this break-point was due to the different mode of the fatigue deformation mechanism which is associated with the plastic strain amplitude. The fracture surface of base metal and HAZ-II showed the distint striations with trans-granular mode, however, HAZ-I showed the combination of inter- and trans-granular mode.
Form these experimental results, it can be conclude that the fatigue properties of Al-7017 alloy was definitely influenced by the micro-structural changes due to the welding.
