Metal Additive Manufacturing Conference - MAMC 2022

The Collective Research Project 3DWELDING // Additive Fabrication of Structural Steel Elements investigates the possibilities of 3D printing with steel (WAAM - Wire and Arc Additive Manufacturing) in the construction industry. The goal of the project team, which consists of university partners and industrial partners along the value chain, is to develop a fast, economical and stable fabrication process of welded steel parts with material properties commonly used in structural steel construction.
Two fundamental questions are discussed in the paper. The first focus lies on the general geometric possibilities offered by this process. The influence of various parameters such as wire feed speed, travel speed and torch inclination on the seam shape and build-up rate will be presented. The microstructure of the manufactured components is checked and evaluated. Print strategies are developed for different requirements. Necessary cooling times are used effectively due to an alternating strategy. Temperature management in the components mostly describes the critical path.
Therefore, suitable process parameter sets are defined. These obtained parameters were then used to fabricate different samples.
The second focus is on testing and determining the material strength to be achieved. In the course of the project, different filler metals up to a nominal steel grade of S460 equivalent are tested with regard to their strength, with a particular focus on the joint area between substrate and welded structure. For this purpose, test methods for testing additively fabricated components are being newly developed. In particular, shear tests parallel and transverse to the welding direction require new approaches.
Knowing the geometric and mechanical properties, in order to be able to guarantee safe application of the different materials, a parameter window for each material is defined. It is thus ensured that within this parameter window, while maintaining the specified interlayer temperature, the printed structure always meets the necessary requirements for strength and stiffness.