Fillet Welds on ASTM A36 Steel Using AWS ERNi-1 Electrode Subjected to "Out-of-Plane" Structural Impact Loads

There is a growing interest in the behavior of weldments under extreme loading conditions, such as structural impact loads. This is partly because most Codes and standards for designing welded joints are usually based on tests conducted under quasi-static or fatigue loading conditions. The primary aim of this study was to investigate the behavior of GMAW fillet welds on ASTM A36 structural steel using a high ductility electrode (AWS ERNi-1). Fillet welds were made between two sides of equal length of a very thick rectangular plate and a base plate of the same steel. Each pair of weld beads was then subjected to “out-of-plane” structural impact loads combining a relatively large moment due to bending and loads applied transversely to the fillet welds. Impact test results obtained with AWS ERNi-1 were compared with data from tests using a base metal-matching electrode, AWS ER70S-6. In this comparison, it was found that the weldments made with AWS ERNi-1 exhibited fracture initiation energy 213% higher than those made with AWS ER70S-6. Vickers hardness tests were also conducted on weld beads made with AWS ERNi-1. Comparing the hardness results before and after impact, it was found that the weld metal became up to 93% harder and the heat-affected zone up to 42% harder after impact. The fractured surfaces of the AWS ERNi-1 weld beads were analyzed and revealed characteristics typical of ductile fractures.