U02 - Laser Deep Alloying for the Realization of Finely Graded Alloys

U02 - Laser Alloying

One of the main advantages of the laser is its high processing speed and precision. This makes it a particularly suitable tool for high-throughput applications. In laser alloying, the high power density of the focused laser beam is used to melt the base material and alloy elements, thus enabling metal bonding. In subproject U02 micro-samples of different alloy compositions are produced. They will be used to generate thermally and mechanically induced property changes – the so-called “colored states” – and to determine descriptors.

For this purpose, research is being carried out on a novel laser-based alloying process, by which many reproducible alloys can be produced in fine graduation of their chemical composition. In a first process step, alloy elements are pre-deposited on the base material, primarily by thin powder layers using selective laser beam melting (LBM). In the following step, the alloys are produced by laser-based remelting and mixing of the alloy element layers with the substrate using a scanner-guided laser deep alloying process.

The aim of the project is the reproducible production of homogeneous alloys of defined composition with high throughput. This requires complete control of the laser deep alloying process in terms of the weld penetration and the homogeneity of the remolten pool. A desired remelted volume shall be guaranteed by in-situ control of the welding depth. The alloying homogeneity is to be ensured by in-situ detection of the emission spectrum of the process-induced plasma. In the study, the influence of different scanning strategies on the homogeneity of the remolten pool should be examined. Another challenge is to achieve a uniform microstructure of the alloy. This requires a subsequent laser-based heat treatment with controllable cooling.

The subproject is at the forefront of the entire process chain of the “colored states” method as a primary forming process. Accordingly, it is strongly networked with all project areas about the provision of the required samples and data exchange. In addition, the subproject plays a “coloring” role. Spherical micro samples from the U01 subproject are subjected to laser-based short-term heat treatment, which provides further insights into the influence of the applied materials and parameter sets on the resulting microstructures.

The long-term goal of the subproject in the further phases is, among other things, to increase the flexibility and automatability of the deep alloying process with a view to high-throughput capacity while ensuring maximum reproducibly of the samples. The aim is to provide an even wider range of alloy and microstructure states for the SFB1232 method for the exploration of evolutionary structural materials.

Publications

Konstantin Vetter, Hannes Freiße, Frank Vollertsen. High-throughput material development using selective laser melting and high power laser. 7.WGP-Jahreskongress, p. 511-518, Aachen, Germany, 2017 [Link zur Konferenz] [Link zum PDF]

Konstantin Vetter, Sven Hohenäcker, Hannes Freiße, Frank Vollertsen. Use of additive manufacturing for high-throughput material development. Lasers in Manufacturing Conference 2017 (LiM), Munich, Germany, 2017 [Link zur Konferenz]

Konstantin Vetter, Hannes Freiße, Frederik Feuerhahn, Henry Köhler, Frank Vollertsen. Influence of scanning strategy on alloy generation. THE LASER USER, Issue 83, p. 32-33, 2017 [Link zum PDF]