Abstract:Nickel based superalloy, Inconel 718, is one of the main candidates for high temperature applications such as air craft, land base and marine turbines. This technical paper deals with high temperature erosion behaviour and its mechanism of Al 2 O 3 -40TiO 2 (A40T) coating on Inconel 718 alloy. Al 2 O 3 -40TiO 2 coatings through plasma spray method were made on Inconel 718. The erosion behaviour of the A40T coating was studied using hot air jet erosion experiments at 800uC with varying parameters like angle of … Show more
“…The cavitation erosion results mostly go as expected: higher roughness leads to less resistance and SLM samples are generally less resistant. Roughness is associated with more erosion because surface defects tend to serve as sites for accelerated cavitation damage [ 32 ] and introduce surface irregularities which create high stress regions that promote fatigue cracks [ 33 , 34 ]. Fig.…”
Inconel pipes that transport cryogenic fluids in rocket engines manufactured by additive manufacturing (AM) were eroded by cavitation. The AM method selective laser melting (SLM) was used to manufacture at lower cost, but had seemingly lower erosion resistance. The cavitation erosion properties of Inconel 625 and 718 are studied as a function of hardness and surface roughness with the ASTM G134 cavitating jet. The samples were studied 3 surface conditions, as deposited/as used in applications, machined and polished, for both forged and AM manufacturing. Indentation reveals slight surface hardening for machined samples. X-ray diffraction (XRD) shows similar polycrystalline
γ
-Ni-based microstructure for all samples. Scanning electron microscopy (SEM) images of the cut cross-sections reveal the fractures and pits, as well as some porosity in the case of SLM samples. Images of the surfaces during erosion reveal some fracture mechanisms: machined samples erosion start quickly on pits and scratches. The SLM718 samples were found to have good cavitation erosion resistance if machined, while the SLM625 samples have comparatively poorer resistance. As-deposited samples have the lowest resistance, and surprisingly machined samples are more resistant than polished.
“…The cavitation erosion results mostly go as expected: higher roughness leads to less resistance and SLM samples are generally less resistant. Roughness is associated with more erosion because surface defects tend to serve as sites for accelerated cavitation damage [ 32 ] and introduce surface irregularities which create high stress regions that promote fatigue cracks [ 33 , 34 ]. Fig.…”
Inconel pipes that transport cryogenic fluids in rocket engines manufactured by additive manufacturing (AM) were eroded by cavitation. The AM method selective laser melting (SLM) was used to manufacture at lower cost, but had seemingly lower erosion resistance. The cavitation erosion properties of Inconel 625 and 718 are studied as a function of hardness and surface roughness with the ASTM G134 cavitating jet. The samples were studied 3 surface conditions, as deposited/as used in applications, machined and polished, for both forged and AM manufacturing. Indentation reveals slight surface hardening for machined samples. X-ray diffraction (XRD) shows similar polycrystalline
γ
-Ni-based microstructure for all samples. Scanning electron microscopy (SEM) images of the cut cross-sections reveal the fractures and pits, as well as some porosity in the case of SLM samples. Images of the surfaces during erosion reveal some fracture mechanisms: machined samples erosion start quickly on pits and scratches. The SLM718 samples were found to have good cavitation erosion resistance if machined, while the SLM625 samples have comparatively poorer resistance. As-deposited samples have the lowest resistance, and surprisingly machined samples are more resistant than polished.
“…Ni-based superalloys, widely used as industrial gas turbine, guide vanes, and turbine disks, exhibit excellent corrosion and oxidation resistance, as well as appropriate strength at high temperature. Among them, Inconel (IN) 718, as a typical Ni-Cr-Fe austenite (γ) superalloy, exhibits superior creep performance and fatigue strength at 253-650°C, as well as excellent oxidation resistance and favourable weldability [1,2,3,4,5]. This makes them one of the basic commercially used materials used as the core element of hot-end components in energy and aerospace industry such as turbine blades and combustion chambers [6,7].…”
In this work, WC/Inconel 718 composite was fabricated by selective laser melting (SLM) the IN718 superalloy powders decorated with surface embedded WC powders. Also, the composite was heat-treated by a designed double-aging regime for microstructure tuning. The resulting microstructure and surface oxidation behaviour of the as-printed and the heattreated composites were studied. The results revealed that the homogeneous microstructure was obtained, and the obvious weld beads structure with fine dendrites was detected on the surface in the SLM composite. After the double-aging heat treatment, the matrix showed a confined growth from 21.81 to 26.14 μm and the weld bead structure disappeared. XRD and EBSD analysis confirmed the formation of γ, γ ′ , γ ′′ , WC, (Nb,M)C, δ and Laves phase in the composites before and after heat-treatment. The high-density GND accommodated the strain incompatibility and the internal residual stress in different constituents. Furthermore, the underlying mechanism of oxidation behaviour was discussed.
“…SPE behaviour of most of the materials can be categorised as being either brittle or ductile in nature [6], [19][20][21][22]. The major difference between the two types of mechanism is the dependence of erosion rate on impact angle, namely the angle between the incident erodent particle and the material surface [23][24][25]. There is a general agreement that maximum erosion occurs at a low angle (about 30°) for ductile material and at 90°for brittle material.…”
Plasma-sprayed NiCrBSi-graphite coatings have been subjected to solid particle erosion at elevated temperatures. The work reports the erosion resistance of NiCrBSi coatings with 4, 6 and 8 wt-% addition of graphite and optimum graphite content for erosion resistance. The coatings were analyzed using optical microscopy, XRD and scanning electron microscopy. Testing was carried out using air-jet erosion test rig, at an impact velocity of 70 m s−1 and at 45°and 90°angles with sand flow rate of 1 g min−1 at RT, 500°C and 650°C. Morphology of eroded surface shows crater, lip, groove formation and chipping as visible mechanism of material removal. Coating with 4wt% distribution of graphite exhibits higher erosion resistance as compared to the coating without graphite addition and improved microhardness. Microstructure images reveal that increase in graphite content above 4% results in the segregation of graphite and leading to soft islands in the coatings thereby decreasing the erosion resistance.
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