Basically there are two ways how to asses mechanical properties of AM deposited materials: deposition of separated samples for mechanical test of standard dimensions or extraction of the samples directly from the component. In many cases the component due to its complex shape and wall thickness does not allow standard samples extraction. Therefore small sized specimens are unavoidable and these can be either extracted directly from the components, of samples of similar wall thickness can be separately deposited in order to represent the real component behavior. Contribution presents mechanical properties assessment of AM deposited materials by EBM, SLM and powder blown Directed Energy Deposition systems. Local and orientation related properties with the use of miniaturized samples are presented for several single material parts as well as for multiple material ones.
TWAS technology is established and widely used in practice for spraying metal alloy-based coatings, benefiting from the low cost of the device and the mobility, enabling the coatings application even on large structures without the need for disassembly. There are a number of components in the energy industry that can profit from the application of protective coatings. Often, these are surfaces stressed by a combined load - mechanical wear, corrosive environment, and high temperature. It is often impossible to meet all requirements by applying one type of coating. Multilayer coatings have greater potential in this case. This paper presents selected TWAS coatings designed for application in corrosive environments. The influence of deposition parameters on the microstructure and the potential of their optimization to achieve coatings with better behavior are discussed, selected properties of different spraying materials under abrasive and erosive stress are compared and their ability to protect the base material in different types of corrosive environments is evaluated. The examples of multilayer coatings designed for specific working conditions are presented.
This article is devoted to metal powders used in additive manufacturing and to the basic precautions and principles of its safe handling. In the first part, the principle of additive manufacturing based on the powder bed fusion method is described as well as its requirements for the materials used, commonly used materials, basic possibilities of manufacturing such materials and their properties and characteristics. In the next part, the safety and health hazards arising from working with powder metals are described followed by necessary protective work equipment, accessories, and precautions for long-term safe work with metal powders in additive manufacturing.
Additive manufacturing (AM) ranks among the most expanding technologies of the industrial sector
over last years. A complex structure is characteristic for Functionally Graded Composites, which basics, principles and applicability have been widely investigated recently. The present study is focused on the detailed investigation of mechanical and structural properties of FGC consisting of stainless steel 316L and Inconel 718 processed by Powder Blown Directed Energy Deposition system. Effect of the variable multi-material interface orientation was investigated. Horizontal, vertical and inclined interfaces (15°, 30°, 45° and 60°) were compared using miniaturized tensile test and imaging techniques. The results show that the porosity and cracks evolution is strongly dependent on the multi-material interface orientation.
Directed energy deposition (DED) demonstrates a great potential in the effective fabrication of metallic parts with large volume, functionally graded materials, as well as repair of components with geometrically complex structure. Creep behaviour of a coarse-grained Inconel 718 fabricated by DED technique was investigated at 650 °C/700 MPa with comparison to a conventional wrought material. Various heat treatments involving double aging (DA), standard heat treatments (STA-980-1180 °C) and hot isostatic pressing (HIP) were applied to tailor the microstructure and thus improve the creep performance. Microstructure characterization and fracture analysis were carried out to observe microstructural changes and their influence on creep behaviour and facture mechanism. Results show that, DED sample heat treated by a simple double aging exhibits a 49% increase in creep life and a superior creep ductility compared to the wrought material, due to the enhancement of the inherited L-DED-induced microstructural characteristics i.e., dislocations cell substructures and random orientation of grains separately by complex high angle grain boundaries. A higher heat treatment temperature above 1080 °C results in a much shorter creep life and worse creep ductility, which can be attributed to the occurrence of grain coarsening and the loss of the DED-induced microstructural features. HIP heat treatment does not contribute to an enhanced creep performance for DED-IN718, probably due to the much denser and low pores samples fabricated by DED process. The present work demonstrates that DED-manufactured IN718 with a coarse grain feature shows a great advantage for the simultaneous enhancement of creep strength and ductility. A simple double aging treatment is sufficient to preserve the DED-induced microstructural features as well as precipitate strengthening phases for promoting a superior creep performance.
Today’s industrial production increases demands on high quality goods, joining technology, additive manufacture (3D printing), laser melting and welding, sintering, minimizing of product waste from testing procedures and others. Temperature plays a decisive role in all of these processes. Therefore, all of such procedures massively adopt infrared camera systems for inspecting parts, thermal imaging, monitoring and process control thanks to its high-speed recording, wide temperature range and both automated and laboratory possibilities.
The mapping of heat flows in components is necessary for a complete understanding of the process and allows precise control of the temperature development in the parts and materials to be processed as well as exact thermal control of the process. Brazed and laser-welded joints can be tested with active thermography in fully automated or semi-automated testing systems in a timely manner. Active thermography is the induction of a heat flow by energetically exciting a test object. The heat flow is influenced by interior material layers and defects. These inhomogeneities can be captured on the surface by high-precision infrared cameras. The additional evaluation algorithms improve the signal-to-noise-ratio which allows for detection of smallest defects.
Material tests using thermal imaging by infrared camera save time and costs as test object will not be destroyed during process. They can be used for further testing or locating quality problems that could be corrected. IRNDT tests with infrared camera systems provide good solutions with greater applications as they can be used for a wide range of different materials and types of defects.
The skin-implant interface remains an unresolved problem in implantology as prone to recurrent and persistent difficulties originating from the lack of integration. The aim of our study is to develop durable skin seals for long-term viability via reduction of infection and biofilm formation. A biometric approach was chosen, where an existing interface of skin and antler serves as a motivation. The study includes a thorough analysis of the interface including micro CT tomography and mechanical characterization by nanoindentation. The result is a novel structure, that has the potential to improve transcutaneous implant viability.
Multimaterial structure consists of combination of different materials, here Inconel 718 and stainless steel 316L, and it was prepared by deposition of alternating layers in powder-blown directed energy deposition process. Thermal properties, such as thermal expansion, specific heat, thermal diffusivity and thermal conductivity was measured for both pure materials and different interfaces originated according to the order of deposited materials in the temperature range up to 700°C. Wider transition zone due to more effective element mixing in the case when 316L was laid on Inconel 718 layer led to higher thermal diffusivity and thermal conductivity compared with the other arrangement of deposited materials.
Directed Energy Deposition (DED) is one of the additive manufacturing technologies that allows the depositing of bulk parts using individual deposited layers. DED technology can be used to manufacture tools or repair damaged edges and surfaces. Forming and cutting tools cause great wear due to mechanical and thermal loading and that can become damage it. The base of tools are made of common or tool steels, on which layers of functional material with properties suitable for forming are applied using DED or Wire Arc Additive Manufacturing (WAAM). These materials with excellent thermomechanical and mechanical properties are nickel, cobalt or tungsten alloys. The forming and trimming tools will increase their service life at least 5 times using functional edge made by nickel alloy and thus reduce production costs.
Minor craniotomy is involved in a surgical approach for subdural hematoma evacuation. No applied reconstruction may result in a cosmetic problem but also functional handicap. Mostly used metallic cranial plates do not solve persistence of bone defect and their resistance is limited in long term cycling loading conditions. Alternative devices do not provide sufficient mechanical properties, functionality or aesthetic outcome. Nowadays, additive manufacturing techniques are becoming popular for solving specific anatomic problems. In this study new type of implant for reconstruction of small defects after cranial drilling is introduced. Four variants of modular devices including burr hole ring and cup are proposed together with the approach and instruments for surgical implantation. Finite element model verifies initial construction idea derived from simplified geometry and physiological loading conditions. New test methods for determining strength of locking mechanisms are defined to ensure safety and reproducibility of implants. Alpha prototypes are manufactured and test methodology is verified. The variant of metallic burr hole ring disposing with overlap on bone surface after implantation was proven as the safest solution. The idea of the new cranial implant may significantly improve the aesthetic outcome after the surgery and minimize invasiveness in reoperations.
Additive manufacturing (AM) is an innovative technology, which can offer creation of customized products to meet specific customer’s needs. Its advantages can be exploited in many industries including automotive, aircraft and biomedicine. In biomedicine, the technology can be employed to create fully personalized implants in terms of geometrical features and mechanical properties, which significantly reduce the risk of stress shielding and implant loosening. The effort is to optimize the AM deposition parameters and develop biomaterials, which are fully biocompatible and available. In the last years, β-titanium alloys have gained attention of researchers due to their low elastic modulus and great biocompatibility, which potentially increase a probability of successful osseointegration. The aim of this study is to investigate the microstructure and mechanical properties of two β-titanium alloys, Ti-13Nb-13Zr and Ti-12Mo-6Zr-2Fe, manufactured using different AM systems. The results showed that the experimental materials are characterized by significantly lower elastic modulus and higher strength than commonly used Ti-6Al-4V.