Influence of the cooling time t8/5 on weld metals
Brian Rust, Jan Schmidt, Richard Stroetmann
Abstract
Abstract The increasing use of high-strength steels in construction has raised the importance of high-strength filler materials. Therefore, precise control of the mechanical properties of these fillers is crucial, as their strength often closely matches that of the base material. Heat input during welding can weaken slightly overmatched joints, turning them undermatched and compromising the safety of the welded component. In this context, the ongoing AiF-FOSTA research project P1453 investigates the impact of cooling time t 8/5 on the mechanical properties of weld metals in gas-shielded metal arc welding. Furthermore, the introduction of the new Eurocode 3 Part 1–8 allows the consideration of the nominal tensile strength of the filler material for fillet and butt welds, directly affecting the design resistance of the welded joint and increasing the importance of the filler material’s tensile strength. Experimental characterizations of filler materials G62 and G89 on new centric drilled flat tensile specimens highlight the correlation between tensile strength and cooling time. The study reveals that the standardized tensile strength requirements for filler materials of strength classes G79 were not reliably met for cooling times of 7.5 s and beyond. Moreover, the study indicates that the filler material E89 consistently fails to meet the specified minimum tensile strength requirements by 5%. However, filler materials such as G35, G42, G62, and G69 consistently comply with normative standards. These results emphasize the critical need to consider welding parameters, particularly cooling time, to ensure weld quality and structural integrity.