GE Aviation, a subsidiary of General Electric, is headquartered in Evendale, Ohio, outside Cincinnati. GE Aviation is among the top aircraft engine suppliers, and offers engines for the majority of commercial aircraft. GE Aviation is part of the General Electric conglomerate, which is one of the world's largest corporations. The division operated under the name of General Electric Aircraft Engines (GEAE) until September 2005. GE Aviation's main competitors in the engine market are Rolls-Royce and Pratt & Whitney. GE operates two joint ventures with Safran Aircraft Engines of France, CFM International and CFM Materials.
This study investigates the feasibility of using cold spray for repair of Inconel 718 (IN718) components. The effect of cold spray parameters on the particle velocity, splat morphology, deposition efficiency (DE), thickness, and porosity was evaluated. Thick coatings of approximately 4 mm were deposited onto ground and polished IN718 substrates using N2 gas heated to 1000 °C with gas pressure of 5 and 7 MPa. The coatings were subjected to standard double aging (DA) and a combination of solutionizing and double aging (STDA) heat treatment. The microstructure, hardness, porosity, tensile strength, and adhesive strength of as-sprayed and heat-treated coatings were evaluated. Additionally, the tensile properties of the coating–substrate combination (sandwich samples) were also evaluated. It was observed that higher gas pressure led to increased particle velocity, decreased porosity, enhanced hardness, and improved adhesion/tensile strength. The splat size increased with higher particle velocity, indicating greater particle deformation. The DE decreased with increase in number of deposited layers and increased with increase in gas pressure. The AS coating microstructure exhibited a deformed powder microstructure having fine dendritic/cellular structure. Following the DA treatment, the dendritic features were preserved, accompanied by the precipitation of γ′, γ′′, and δ phases. After STDA treatment, a homogeneous microstructure with the presence of γ′, γ′′, and Nb and Ti carbides without any δ phase was observed. The most favorable outcomes were achieved with the 7 MPa STDA sample, yielding a minimal porosity level of 0.4 ± 0.1
Negatif Poisson oranına sahip olan ve özellikle enerji absorbe etme özelliğine ihtiyaç duyulan endüstriyel uygulamalarda kullanım imkanı bulan ökzetik yapıların basma, çekme ya da bükme yüklemeleri altındaki mekanik davranışları literatürde incelenmiştir. Fakat bu yapıların, bir eklemeli imalat prosesi olan lazer toz yatağı füzyon yöntemi ile üretilmeleri neticesinde meydana gelen boyutsal sapmaları üzerinde, ökzetik özelliklerinin ne kadar etki ettiği konusunda herhangi bir çalışma literatürde bulunmamaktadır. Bu boşluğun doldurulmasına katkı sağlamak amacıyla, bu çalışmada beş farklı ökzetik yapı (re-entrant, trichiral, anti-thrichiral, tetrachiral, anti-tetrachiral ve hexachiral) ve bir adet ökzetik olmayan yapının (bal peteği), Inconel 718 malzemeden lazer toz yatağı füzyon yöntemi ile üretimi sırasında meydana gelen, katmanlar arası yüksek sıcaklık farklı ve bunun neticesinde oluşan kalıntı gerilmeler ve boyutsal sapma miktarları, termomekanik simülasyon kullanılarak incelenmiştir. Her bir geometriye ait Poisson oranları da hesaplanmış ve karşılaştırılmıştır. Sonuçlar, ökzetik yapıların lazer toz yatağı füzyon yöntemi ile üretilmeleri sırasında da ökzetik özellik gösterdiklerini göstermiştir. Çalışma sonucunda re-entrant yapının en yüksek, hexachiral yapının ise en düşük ökzetik özellik gösterdiği görülmüştür. Bir düğüm noktasına teğet olan duvarlardan oluşan chiral yapılar arasında, hexachiral yapı en fazla boyutsal sapma göstermiştir. Ökzetik olmayan bal peteği yapısı ise, ökzetik yapılara göre daha fazla boyutsal sapma göstermiştir.
Multi morphology lattices are composite lattice structures formed by different types of lattice structures in different configurations based on engineering application needs. These types of lattices can be manufactured with additive manufacturing modalities, specifically laser powder bed fusion process. However, due to the high cost and time spent on manufacturing these components, it is necessary to predict the properties of manufactured parts before build with numerical methods. This study focused on prediction of dimensional deviation of laser powder bed fusion produced multi morphology lattice structures composed of Schoen Gyroid, Schwarz Diamond, Schwarz Primitive, Schoen FRD and Neovius topologies via thermomechanical simulations qualitatively. Since the comparisons were made based on numerical study results, only qualitative assessments were performed. Lattices were generated by using a novel, in-house developed tool. Among multi morphology lattices investigated in the present study, Schoen FRD topology at the center and Schwarz Primitive topology at the outer region showed the lowest deviations and Schoen FRD topology at the center and Schwarz Diamond topology at the outer region showed the highest deviations. It was also shown that adding Schoen FRD or Schwarz Primitive topologies at the outer region reduces the max. deviations, and Schoen Gyroid or Schwarz Diamond topologies increases the max. deviations.
Additive manufacturing technologies give engineers and researchers a high level of design freedom to produce complex components or entire assemblies previously impossible or impractical to manufacture by conventional means. Although additive manufacturing has many advantages compared to conventional machining, it has some drawbacks, two of which are higher surface roughness and dimensional inaccuracy of as-built part surfaces especially in overhang features. Support structures are one of the solutions to mitigate these drawbacks at a cost of additional post-processing efforts. The aim of the present study is to investigate the effect of different support geometries on the mechanical properties of laser powder bed fusion manufactured Inconel 718 overhang parts. The tested support geometries are comprised of several pieces to ease post-processing instead of using single-piece supports filling all over the overhang surface. One of the tested support structures is contactless support with no direct contact between the part and the support itself. The others are tooth support where the contact is on the tooth faces and line support where the contact is along a line. The thickness of each support piece and the spacing between the two support pieces were used as design variables. The dimensional accuracy of printed specimens with respect to the computer-aided geometry, distortion of overhang features, microhardness through the thickness, microstructural changes of overhang surface, and surface roughness of overhang features was experimentally evaluated. The results revealed that support type, support spacing and support thickness directly affect the performance characteristics used in this study.
In this work, the effect of double-aging (DA) heat treatment on the microstructure and the tribological behaviour of cold-sprayed Inconel 718 (IN718) coating was studied and compared with hot-rolled IN718. After double-aging, the dendrite structure of the as-sprayed coating was modified and secondary phases such as γʹ, γʺ, and δ phases were formed. The microhardness of the coating improved after double-aging and was higher than the double-aged IN718 due to the leftover microstrain in the coating. Sliding wear tests were carried out at room temperature (RT) and 600 °C using a ball-on-disc tribometer with alumina balls. The double-aged coating had improved wear resistance than the as-sprayed coating and the double-aged substrate at room temperature. At 600 °C, the wear rate of the hot-rolled IN718 was marginally lower than the as-sprayed coating due to the formation of a comparatively thick mechanically mixed layer (MML) reinforced with Al2O3 which was more protective in nature. The double-aging treatment improved the wear resistance of the coating significantly at 600 °C and its wear rate was comparable to that of the double-aged substrate. The substrate and the coating undergo a combination of abrasive and tribo-oxidative wear at RT. At 600 °C, the wear mechanism involves a combination of oxidative and abrasive modes. Raman analysis revealed that the oxide formed on the wear track consisted of NiO and Fe3O4 at RT, and the glaze layer formed during high-temperature wear consisted of a mixture of the NiFexCr2-xO4 spinel and Fe3O4.
