Influence of the Delta Phase in the Microstructure of the Inconel 718 subjected to “Delta-processing” Heat Treatment and Hot Deformed

AbstractInconel 718 (IN718) is a nickel base alloy widely used in the aerospace industry due to its mechanical stability at elevated temperatures. Stable δ phase with acicular morphology weakens the IN718, however, it has been found that a spherical morphology distributed in the grain boundaries acts as an anchor preventing grain growth during hot deformation. The delta processing (DP718) is a saturation of δ phase in the alloy by thermal treatment followed by thermomechanical working to control the grain growth and morphology during deformation. Two specimens (A and B) of IN718 alloy were solubilized for 1h at 1100°C WQ and aging at 900°C for 24hWQ thermal treatment, following bythermomechanical deformation. Sample A was deformed at 0.001 s -1 and sample Bat 0.01 s-1, both deformations were carried out at 960°C and the final microstructures were characterized by optical microscopy and scanning electron microscopy (SEM) in order to evaluate morphology and grainsize distribution

High-temperature deformation of delta-processed Inconel 718

© 2017 Elsevier B.V. The hot-flow behavior of Inconel 718 subjected to delta processing (DP) was analyzed. Hot compression tests were subsequently performed at 960 °C and 1020 °C at the four different strain rates of 0.001, 0.01, 0.1, and 1 s-1. The two deformation temperatures were located below and above the d-solvus of IN718 respectively. Microstructural characterization was performed by means of optical (OM) and scanning electron microscopy (SEM). The high temperature deformation results in the fragmentation of the existing d-phase by means of partial dissolution and/or deformation, leading to an improved grain size control. A classic dynamic recrystallization (DRX) behavior was observed in the flow curves, which is typical of low-medium stacking fault energy (SFE) alloys. This flow behavior was modeled according to various approaches. Peak stress modeling was performed using two different approaches, referred to as ‘apparent’ and ‘physically-based’. The hot-flow behavior before the peak stress was modeled according to the Estrin-Mecking-Bergstrom approach, with Avrami kinetics employed to describe the DRX behavior.Peer ReviewedPostprint (author's final draft

X-ray determination of compressive residual Stresses in spring steel generated by high-speed water Quenching

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about -700 MPa were obtained.Peer ReviewedPostprint (published version

Sexual Size Dimorphism and Body Condition in the Australasian Gannet

Funding: The research was financially supported by the Holsworth Wildlife Research Endowment. Acknowledgments We thank the Victorian Marine Science Consortium, Sea All Dolphin Swim, Parks Victoria, and the Point Danger Management Committee for logistical support. We are grateful for the assistance of the many field volunteers involved in the study.Peer reviewedPublisher PD

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X

We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.EC/H2020/633053/EU/Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium/ EUROfusio

Annealing of a ferritic stainless steel 409 stabilized with titanium and zirconium additions

A ferritic stainless steel 409 stabilized with titanium and zirconium was subject to thermomechanical processing. It was heated at 1210 °C for one hour, followed by a 75 % hot reduction in three passes, this rolling schedule ended at 980 °C. Samples were cooled to 600 °C by water spraying followed by air-cooling. The alloy was pickled, and was reduced 80 % by cold rolling. The alloy was annealed at different temperatures for 105 s. Additional annealing treatments were carried out at temperatures of 800, 850 and 900 °C for different times. Mechanical testing and texture were made to corroborate the degree of annealing and formability. Mechanical properties and Texture analyses showed that the alloy annealed at 850 °C for 14 min was both completely recrystallized and a very good formability.<br><br>Un acero inoxidable ferrítico 409 estabilizado con titanio y zirconio fue sujeto a procesos termomecánicos. El acero fue calentado a 1210 ºC durante una hora, seguido por un laminado en caliente del 75 % en tres pases, el proceso terminó a los 980 ºC. Las muestras fueron enfriadas hasta 600 ºC por agua atomizada seguido de enfriamiento al aire. La aleación fue decapada y laminada en frío un 80 %. Posteriormente de desarrollaron tratamientos térmicos de recocido a diferentes temperaturas por un tiempo de 105 s. Adicionalmente se desarrollaron tratamientos de recocido a temperaturas de 800, 850 y 900 ºC a diferentes tiempos. Pruebas mecánicas y textura fueron realizadas para corroborar el grado de recocido y su formalidad. El análisis de las propiedades mecánicas y la Textura mostraron que la aleación recocida a 850 ºC por 14 min (840 s) fue completamente recristalizada obteniendo la mejor formabilidad