Additive Manufacturing
STW-M2i: High Tech Materials
Wire + Arc Additive Manufacturing of Titanium Alloys, FunWAAM
PhD student Mr. Vamsi Krishna Paruchuri
Supervisor Dr.ir. Marcel Hermans
Wire arc additive manufacturing involves constructing three-dimensional components out of weld metal by deposition of successive layers. Wire arc processes offer build rates two orders of magnitude or more higher than powder bed sintering processes (measured in mass deposited per unit time). In this research physically based simulation of 3D components capable of predicting both the thermal and strain histories both during and post deposition will be constructed. The knowledge generated will give insight into the microstructure formation, which will also be experimentally assessed. Understanding the link between the thermal–mechanical history and resultant microstructures provides the basis for assessment of mechanical performance of a construct and hence the determination of fitness for purpose.
Within this research we focus on high added value titanium alloy (Ti-6Al-4V) components for aerospace applications. We will determine whether it is feasible to break down large structures into component features (sub-components) such as thin walls, cross overs, thick walls, T –pieces, pads etc. and qualify the sub-components within defined thermal mechanical ranges. If this can be achieved, then any large component constructed from pre-qualified sub-components should also meet the qualification requirements, provided it can be shown that the sub-components have been constructed within the range of conditions for which qualification has already been achieved. This research should provide the fundamental basis upon which the feasibility of this approach can be assessed.
FOM-Differ M2i
Additive Manufacturing and Welding of ODS Eurofer
PhD student Mr. Jia Fu
Supervisor Dr.ir. Marcel Hermans
For certain applications of oxide dispersion strengthened ferritic martensitic steel (ODS-Eurofer), welding of parts is required. In addition, additive manufacturing (AM) of ODS Eurofer is an area of interest for the nuclear community. Additive manufacturing is based on layer-by-layer deposition of metals to create 3D products and encompasses a wide variety of technologies ranging from powder-based techniques (powder bed and blown powder) to techniques depositing solid wire. In the Strategic Research Agenda of the AM platform it is mentioned that additive manufacturing technology of metals strongly resembles the welding process. It is stated that if a metal is not weldable, it cannot be additive manufactured.
This project will focus on the broad area of the metallurgical aspects of additive manufacturing and fusion welding processes for ODS Eurofer. The primary aim of the project is to generate a better understanding of the response of ODS Eurofer steel to metal deposition and fusion welding process conditions. A large number of factors involved in metal deposition/welding is incorporated in the research program, including a study of the thermal history of the processes, the occurrence of residual stresses in and around the deposit, a characterization of the microstructures obtained and finally the mechanical properties. The focus of the project is to provide information on the evolution of the microstructure upon deposition/welding, in order to optimize procedures for deposition processes and eventually requirements for the steels/filler metals from a processing perspective. In the study of microstructural development the influence of pre- and post heat treatments will be included.
STW-M2i High Tech Materials 2016
Functionally Graded Materials Through Wire Arc Additive Manufacturing, GradWAAM.
PostDoc Mr. Konstantinos Goulas
Supervisor Dr.ir. Marcel Hermans
Innovative design of products demands the ability to tailor the microstructure to the property requirements at specific locations in a product. Wire and arc based additive manufacturing processes are novel technologies to create complex large scale 3D-structures that enable functional and compositional grading by selection of appropriate process conditions or by means of multiple wire feed techniques.
In order to be able to create this local difference of properties, the relationships between Wire Arc Additive Manufacturing (WAAM) process conditions, the thermal history during the building process and the resulting microstructure (i.e. the properties) of the materials considered, needs to be fully understood.
The approach followed in this project starts with the determination of a processing window were process parameters are related to deposition geometries and deposition rates. For each condition, process stability will be determined, the thermal cycle will be recorded, microstructures are characterized and mechanical properties are measured. Based on these characteristics, simple structures (sub-components) will be defined, and built by the deposition of successive metal layers. The effect of additional thermal cycles on the microstructure and properties will be established. Anisotropic effects on microstructure and properties due to unidirectional solidification will be considered. Furthermore, residual stresses and geometrical deviations from the originally designed structure will be determined. Experimental investigations will be accompanied by physics based microstructural and finite element thermo-mechanical models.
The obtained data sets will form the starting point to create functionally graded structures by variations in i) process conditions and ii) chemical composition. The latter will be established by multiple wire feeding. The full range of characterization techniques will be applied to determine the integrity of the construct.