Marleen Rombouts

Laser metal deposition of Inconel 625: Microstructure and mechanical properties

Laser metal deposition (LMD) is used in industry to coat, additive manufacture, and/or repair high value metal components through deposition and laser induced melting of powder delivered in a gas stream. This study relates to the production of three-dimensional Inconel 625 components by LMD. After LMD, a dense cellular – dendritic structure containing carbides of the type MC, M23C6, and M6C has been detected by x-ray diffraction. Parts with tensile yield strengths, ultimate strengths, and elongations in the range of, respectively, 480–656u2009MPa, 882–1000u2009MPa, and 24%–36% have been obtained. Compression testing along and perpendicular to the build direction reveals a slight anisotropy in fracture strength. This is attributed to the preferential orientation of the dendrites parallel to the build direction. Tensile test samples have been fabricated in “lying” and “standing” orientations. The tensile yield and ultimate strength are considerably lower and the elongation is larger for the samples built in standin...

Feasibility study on integrated structural health monitoring system produced by metal three-dimensional printing

Numerous structural health monitoring systems have been investigated extensively in order to enhance safety level and reduce direct operational costs. This work demonstrates the feasibility study of a new concept, the effective structural health monitoring system. The effective structural health monitoring system detects cracks using a system of capillaries incorporated into a structure. The structure with the integrated capillaries is produced by additive manufacturing, a process of adding material layer by layer. The first objective of this study is to prove that the developed system has reached technological readiness level 3. In order to prove that, four-point bending specimens with the integrated effective structural health monitoring system were tested after being produced by additive manufacturing, more specifically by laser metal deposition. The second objective of the study is to indicate that during four-point bending fatigue tests, the integrated structural health monitoring system has no influence on the crack initiation behavior. To do so, the specimens were subjected to the so-called step method. We demonstrate that the effective structural health monitoring has reached technological readiness level 3 and that the presence of effective structural health monitoring did not negatively influence the fatigue initiation process. As higher technology readiness levels are required, further investigations are still in progress.

Alkaline corrosion properties of laser-clad aluminum/titanium coatings

Purpose – The purpose of this paper is to study the use of titanium as a protecting element for aluminum in alkaline conditions. Design/methodology/approach – Aluminum coatings containing up to 20 weight per cent Ti6Al4V were produced using laser cladding and were investigated using light optical microscope, scanning electron microscope – energy-dispersive X-ray spectroscopy and X-Ray Diffraction, together with alkaline exposure tests and potentiodynamic measurements at pH 13.5. Findings – Cladding resulted in a heterogeneous solidification microstructure containing an aluminum matrix with supersaturated titanium (<1 weight per cent), Al3Ti intermetallics and large partially undissolved Ti6Al4V particles. Heat treatment lowered the titanium concentration in the aluminum matrix, changed the shape of the Al3Ti precipitates and increased the degree of dissolution of the Ti6Al4V particles. Corrosion testing showed significant localized dissolution of the aluminum matrix. Research limitations/implications – In...