MIG Brazing as a Means of Fatigue Life Improvement

Abstract

MIG-brazing is examined as a potential fatigue strength improvement method for welded structures. The fatigue strength of joints produced using MIG-brazing as the primary joining technique and for the improvement of joints welded using traditional welding was studied experimentally. The effect of the improvement for a typical structural steel weld is achieved by a final pass along the weld toe using MIG-brazing. In total, 31 fatigue test results are presented. These include four pilot cases of welded cruciform joints and two main cases of plates with transverse attachments. The results of the fatigue tests were compared to IIW recommendations for as-welded and improved welds. The fatigue strength of MIG-brazed joints was good. For transverse non-load-carrying attachments, an improvement of 70–80 % measured as local nominal stress was gained with respect to IIW recommendations. The fatigue strength of solely MIG-brazed joints and joints improved by MIG-brazing was almost equal. As an alternative joining method, MIG-brazing is used in some industrial applications. This study has given clear indications that this method could also potentially be used as a weld improvement method for new or repaired structures. However, additional research is needed in order to gain more confidence that the degree of improvement can reliably be obtained in production.