Targeted influence on the weld strength of high-strength fine-grain structural steels in the GMA welding process through functionalized weld material surfaces

摘要

The development of high-strength and ultrahigh-strength fine-grain steels is especially enhanced due to requirements in the range of mobile crane construction, bridge construction, and general steel construction purposing a consistent utilization of lightweight construction and an increase of payloads. However, currently available filler metals limit the use of novel fine-grained structural steels in modern welded constructions, since the strength of the steels in the weld metal can neither be achieved nor exceeded Heuser and Jochum (Mater Werkst 38(7):515-520, 2007). The coating of GMA welding wire electrodes by means of PVD coating processes enables the application of thin, functional layers influencing the welding process and the weld metal. The mechanical and technological properties of the weld metal can thus be influenced to an extent that cannot be achieved even with state-of-the-art welding consumables. The influence of niobium, zirconium, and nickel layers is shown in the described investigations. In particular, the fine-grain and carbide-forming effect of niobium and zirconium and the associated influence on the mechanical and technological characteristics are illustrated. In addition, the effect of a nickel-coated welding wire electrode on the weld metal is explained. The toughness properties are at the focus of the investigations. The aim is to increase the strength while retaining the toughness properties as far as possible.