scope:

This report discusses the results of a research program on the fatigue behavior of sound weldments in thick aluminum alloys. The specimens of alloy 5083-0 were provided by three aluminum companies and included plain plates, longitudinally welded plates and tranversely welded plates.

Axial fatigue tests were conducted on 54 specimens. The results are shown in S-N diagrams. In addition, a supplemental test program was conducted. This program included the study of residual stresses, weld geometry, and weld quality. Conclusions reached from the study are:

1. Orientation of the weld in the direction of stress applications is beneficial to fatigue strength of a joint.

2. The angle at the toe of the weld reinforcement is the most critical factor in the determination of the fatigue life of an as-welded transverse joint.

3. The actual maximum stress at the weld toe, determined from the nominal stress and stress concentration factor, appears to give a much better indication of expected fatigue life.

4. The fatigue lives of one inch thick welded plates of 5083-0 are significantly lower than those obtained for thin welded plates