High Cycle Fatigue Behavior and Microstructural Characterization of 6013-T4 Aluminum Alloy Laser Welded Joints

Abstract

Laser beam welding (LBW) may be used in the place of the traditional riveting process for the welding of the stringers to the skin in aircrafts. This work intends to investigate the mechanical behavior of laser welded aluminum AA6013, subjected to post-welding heating treatments (PWHT). A fiber laser with an average power of 1.5 kW was used to weld two 1.6mm thick sheets in T-joint configuration. After welding, the samples were separated in three groups: the first just welded, the second subjected to a PWHT during 4 hours at 190°C and the third during 2 hours at 205°C. Hoop tensile tests showed that the thermal treatment at 190 oC for four hours increased the tensile strength in 76 MPa, but the strain had decreased 4%; the thermal treatment at 205 oC for two hours increased maximum strength in 65MPa, with a decrease in strain of 5%. In T-pull tensile tests, the tensile properties of as-welded and PWHT samples remained the same. Standard S-N curve showed that the welding reduce the number of cycles to failure for the tested stairs. PWHT did not affect fatigue properties.