The Lack of Penetration (LoP) defect is one of the flaws that can be generated during the friction stir welding (FSW) process. Depending on the size, the depth and the severity of the LoP defect, it is possible that it is hardly detectable by optical inspection or other NDT methods. Whether detectable or not, this defect may lead to a significant degradation of the fatigue properties of the welded material, as the improperly welded zone can act as a fracture initiation site. The paper aims to discuss these issues.
In this experimental investigation, an attempt is made to assess and compare the fatigue behavior of FSW aluminum joints with and without the LoP defect.
It was found that the LoP defect affects the fatigue behavior of the welded material at high stress levels whereas the effect diminishes with decreasing stress levels.
Depending on the design stress levels, the LoP defect may dominate fracture and thus, the welding parameters should be carefully selected so as to avoid such defect.
