Development of the strongest welding consumables

The need of constructions with reduced weight and the requirement of carrying higher loads increase the demands on high strength steels. Developing high strength filler materials with acceptable toughness is an essential task for the realization of these ultra-high strength steel designs. The development of filler metals has reached now its limitation at a yield strength of 960 MPa. In order to increase the strength and reach an adequate toughness level the usage of micro-alloying elements is considered as an alternative concept compared to the conventional solid solution strengthening. These micro-alloying elements can influence grain growth behavior during solidification and cooling and increase therefore the toughness. Furthermore they can promote the formation of precipitates which result in a strengthening effect. For evaluation of the influence of different alloying elements, trial alloys of metal-cored wires were produced and tensile and notched impact samples of all-weld metal were machined. The results are presented and the most effective alloying concept for increasing the strength and maintaining the toughness is shown. Furthermore first results from comprehensive microstructural characterization are presented. Thereby atom probe tomography was applied in order to reveal the atomic-scale microstructure. These investigations should help to understand the structure-properties relationship of high strength welding consumables.