Influence of weld porosity on crack size estimations in Single Edge Notched Tension (SENT) testing of steels: A numerical study

Abstract

Abstract The acceptance of weld volumetric imperfections such as porosity from the perspective of structural integrity is guided by workmanship criteria. However, there is a lack of knowledge on how and to what extent volumetric imperfections can affect the outcome of fracture toughness tests. The small size of laboratory test specimens potentializes the relative impact of such imperfections. This study numerically investigates the influence of porosity on two crack sizing techniques commonly applied to single specimen fracture toughness testing, namely Unloading Compliance (UC) and Direct Current Potential Drop (DCPD). The investigation focuses on Single Edge Notched Tension (SENT) specimens, commonly used to characterize fracture behavior in low crack tip constraint conditions. An extensive finite element parametric study was performed where single pores and random porosity distributions were generated by element deletion. The results show that both UC and DCPD crack size estimations are influenced by pores of sizes within workmanship criteria acceptable limits, which in some cases might induce (or contribute to) crack size errors superior to validity limits set by fracture toughness test standards.