What is Hybrid and Additive Manufacturing?
Additive manufacturing is one of the key technologies of the future in modern materials and production engineering. In contrast to conventional manufacturing processes, components are built up layer by layer, enabling complex geometries, functionally optimized structures, and highly flexible component design. At the same time, additive manufacturing places high demands on an understanding of materials, processes, and component properties, as local temperature profiles, solidification conditions, and process parameters significantly influence the resulting microstructure.
Hybrid manufacturing expands on this approach by combining additive processes with additional manufacturing or machining steps. These include, for example, machining, heat treatment, coating, repair, or targeted local modification of components. At the Chair of Materials Science and Testing, we investigate how additive and hybrid manufacturing processes influence the microstructure, defect formation, residual stresses, surface quality, and mechanical properties of materials. The goal is to integrate process control, material behavior, and component evaluation in such a way that high-performance, reliable, and application-oriented material solutions are created.
Research at the Department
Understanding processes, designing materials for specific purposes, and reliably evaluating component properties
At the Department of Materials Science and Testing, we view hybrid and additive manufacturing as an interplay of materials, process control, microstructure, and component requirements. Our focus is on how additive manufacturing processes, downstream machining steps, and hybrid process chains affect microstructure formation, defect structure, residual stresses, surface condition, and mechanical properties.
To this end, we combine modern manufacturing and machining methods with metallographic, microscopic, and mechanical characterization. This allows us to systematically investigate the relationships between process parameters, material condition, and component behavior. A particular focus is placed on the evaluation of additively manufactured and hybrid-machined metallic materials, as well as on the development of materials science-based solutions for reliable, functionally optimized, and application-specific components.
Methods and Skills
From cyclic testing to fracture surface analysis
Targeted material deposition for the fabrication, repair, and functionalization of metallic components. The focus is on process control, layer formation, material bonding, and the resulting component properties.
Additive manufacturing of complex metallic components using a powder bed. The study examines the influence of process parameters, solidification conditions, and defect formation on microstructure and mechanical behavior.
Combining additive manufacturing with downstream machining and heat treatment processes. The goal is to precisely control surface condition, microstructure, residual stresses, and component performance.
Metallographic analyses to evaluate microstructure, pores, cracks, and intermetallic zones. This allows process characteristics of additively manufactured and hybrid-machined materials to be linked to component properties.
Evaluation of mechanical properties such as hardness, strength, ductility, and fatigue behavior. This makes it possible to correlate process parameters with the subsequent behavior of the component.
Analysis of the influence of heat input, temperature control, cooling conditions, and machining strategy on microstructure, defect formation, and mechanical properties.
Projects in this subject area
Overview of Research Projects in the Field of Hybrid and Additive Manufacturing
The production of wear-resistant functional coatings using extreme high-speed laser cladding requires a precise interplay between the material, process control, and coating structure. The focus is on developing dense, low-crack, and mechanically robust coatings based on metallic matrix materials with embedded WC particles.
The study investigates how key process parameters—such as laser power, powder feed rate, relative velocity, spot size, and track overlap—influence the microstructure, defect formation, and properties of the coating. By combining experimental coating trials with metallographic analysis, microscopic characterization, and hardness testing, suitable process windows can be identified. The goal is to gain a better understanding of the relationships between EHLA process control, coating quality, and application-specific performance of highly stressed surfaces.
Coating heavily loaded cast rollers using extreme high-speed laser cladding opens up new possibilities for the targeted improvement of surface properties. The focus is on developing dense, well-adhered, and corrosion-resistant functional coatings that protect the base material and can extend the service life of industrial components.
The study investigates how process parameters such as laser power, powder feed rate, rotational speed, laser spot diameter, and shielding gas flow affect coating quality. By combining systematic experimental design with metallographic analysis, hardness testing, coating adhesion evaluation, and electrochemical corrosion measurement, suitable process windows for functional EHLA coatings can be derived. The goal is to gain a better understanding of the relationships between process control, coating structure, and application-oriented performance of coated cast components.
According to general scientific understanding, it is not possible to unequivocally determine the cause of a change in wave propagation in fiber-metal laminates (FML) when various environmental conditions and changing interlaminar stress simultaneously affect the Guided Ultrasonic Waves (GUW) Structural Health Monitoring (SHM) system. Therefore, in this subproject of the FOR 3022 research group, the effects of individual relevant state characteristics are systematically investigated in order to develop suitable compensation methods and thereby enable reliable damage detection. Experimental methods are used to establish a relationship between wave propagation and damage, as well as to determine the influence of thermal effects or interlaminar prestresses, which are induced in particular by process-related residual stresses during manufacturing. This residual stress describes an internal stress state caused by differing coefficients of thermal expansion within an FML, leading to pre-stress in the individual layers. The study examines glass-laminate-aluminum-reinforced epoxy (GLARE) and carbon-fiber-reinforced polymer (CFRP) steel laminates. Given the differences in stiffness and thermal properties, these two FMLs represent extreme cases in the behavior under consideration. Supporting verification methods based on X-ray and computed tomography (CT) or ultrasonic testing (UT) with volume waves are being used at the University of Siegen in collaboration with the University of Bremen and the Technical University of Braunschweig to establish a clear relationship between wave propagation, internal stresses, and damage features. The specific damage features are used in the other subproject to validate the simulation model and are incorporated into the developed machine learning methods. The goal of the investigations is to gain a sound understanding of how different conditions and impact damage influence the propagation of GUW in FML. Fig. 1 illustrates this approach.
Contact
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