Start date and planned duration: February 2019, 36 months
- Improve the fundamental understanding of microstructure-property relationship for additively manufactured (AM) parts.
- Develop a novel post-build thermal process that results in a standard set of mechanical properties usable by component designers.
- Examine the effect of high temperature exposure on the AM materials.
- Understand the differences between cast and AM parts as a function of the heat treatments required for different routes in order to obtain optimum mechanical properties.
- Improve the mechanical properties of AM parts by optimising heat treatment processes.
The project will develop knowledge and expertise regarding the effect of post-build thermal processing on heat treatable AM materials. To achieve this, we will use standardised AM process parameters to manufacture samples that will then be subjected to different thermal processes, followed by microstructural characterisation and mechanical testing. The work will quantify whether or not a sufficient level of benefit can be achieved via the post build heat treatment.
Based on industrial interest, the work will focus on post-build treatments for AM parts manufactured using titanium (eg Ti-6Al-4V) and nickel based super-alloys (eg Inconel 718). Sample manufacturing will use the laser powder bed fusion (LPBF) method. Manufactured parts will be characterised using optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) facilities to determine microstructural properties in detail and map chemical composition. Additionally, crystal structures, crystallographic orientation and phase identification will be characterised at a microscopic level by electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD) techniques as required.
Once standardised samples have been developed, post-build thermal processing will be undertaken by using a variety of heat treatment methods to stress relieve and potentially improve the properties of the parts. This may include high-temperature furnace treatment under vacuum or inert gas. Multi-step heat treatments and different heating and cooling rates will be investigated. Induction heating might also be tested in order to achieve very rapid heating.
Finally, mechanical testing (and other techniques, potentially including NDT and digital image correlation (DIC)) will be undertaken to provide a quantified method of measuring changes/improvements to material properties.
Benefits to Industry
Industry will exploit the successful project results via a standardised set of post-build thermal treatments that will provide predictable material performance. This could potentially remove the need for qualification of individually built components, significantly reducing development costs and product lead times.
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