Effects of convection patterns on freckle formation of directionally solidified Nickel-based superalloy casting with abruptly varying cross-sections

Qin, Ling; Shen, Jun; Li, Qiudong; Shang, Zhao

doi:10.1016/j.jcrysgro.2017.03.021

Cited by 19 publications

(8 citation statements)

References 33 publications

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“…However, contributions of Mo, Cr, and Ti to density inversion were seen to be low enough to make them negligible. Similar results on how abruptly varying cross-sections affects freckling were also seen in other studies [8,93]. ese studies also revealed that that an increase in withdrawal rate can reduce freckling (data regarding this have been graphically represented in Figure 62), while relatively lesser withdrawal rates were seen to promote freckling due to the dendrites' low growth rate induced as a result of the low cooling rates, which can be easily overpowered by the increased fluid flow rate in the interdendritic region.…”

Section: Freckle Defect Insupporting

confidence: 88%

“…It was also observed that the formation of freckles is highly dependent on the influences of the edges and the curvature of surfaces. One study [93] particularly focused on how the convection pattern can affect the freckling in components with abruptly varying cross-sections. In this study, the evolution of flow and thermal fields was examined numerically with the help of simulation.…”

Section: Freckle Defect Inmentioning

confidence: 99%

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Recent Advancements in the Field of Ni‐Based Superalloys

Selvaraj

Sundaramali

Dev

et al. 2021

Advances in Materials Science and Engineering

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In this review article, research papers related to recent developments in Ni-superalloy technologies have been reviewed in order to provide an insight into recent achievements and the potential for further study, research, and development in this field. In this paper, studies on various aspects of Ni-based superalloys are reviewed, such as production methods, which include widely used casting methods, as well as unconventional alternative procedures, novel techniques, or simulation and prediction of certain alloy casting properties. Reviewing was done by categorising the papers into 4 major categories: manufacturing of Ni-based superalloys, effects of alloying elements, physical and mechanical properties of Ni-based superalloys, and defects in Ni-based superalloys. The process used to make Ni-superalloy parts can have a huge impact on the production process efficiency, the final product’s quality and properties, and the defects formed in it. Investment casting is one of the most common methods for making Ni-superalloy parts. Manufacturing covers studies on various casting methods used to make Ni-based superalloy components, novel techniques and methods developed to improve casting procedures to produce better products, and alternative manufacturing methods like AM and HIP processing. Similar to production process, the role of alloying elements is also very important. Even minor changes in their compositions can cause significant changes in the final product. Simultaneously, these alloying elements appear to be more efficient in the development of new methods to control product quality, suppress defect formation, and improve material properties such as the creep and fatigue. As a result, the effects of various alloying elements used in castings of Ni-based superalloys are thoroughly examined. A material’s properties are its most important components. They assist the industrialist in selecting or developing a material based on the needs of the application/use. With this in mind, many researchers have conducted extensive research on physical and mechanical properties, as well as how to improve them. Fatigue life, stress rupture, creep properties, impact ductility, strain response, stress relaxation behaviour, and so on are some of the most important physical and mechanical properties of Ni-superalloys. This article thoroughly reviews various studies on these properties, how and by what factors they are affected, and how they can be improved. Another important factor to consider when making Ni-superalloy castings is defect formation, which can affect the properties of the final product. Freckle defects, hot tears, porosities, and slivers are some of the major defects that occur in Ni-superalloys during the casting process. This article also reviews in detail about these defects, how they form, and how they affect the final product. These defects were found to have a significant influence on a variety of properties, such as creep, fatigue behaviour, and fracture mechanism. Topics and areas such as reinforcement of Ni-superalloys with the help of CNCs and 3D printing of Ni-superalloys that can provide scope for potential future research are highlighted based on the above-reviewed papers.

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Section: Freckle Defect Insupporting

confidence: 88%

Section: Freckle Defect Inmentioning

confidence: 99%

Recent Advancements in the Field of Ni‐Based Superalloys

Selvaraj

Sundaramali

Dev

et al. 2021

Advances in Materials Science and Engineering

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“…It is known that many types of defects in single-crystalline (SX) turbine blades are created during directional crystallization by the Bridgman technique, while the crystallization front passes through areas with abrupt changes in a geometry of the cast [1,2,3,4,5,6,7,8]. The layers of the blade root located near the plane of connection with a selector (selector-root (S–R) connection), where branching of the primary dendrite arms and lateral growth occur, are especially important for defects creation [9,10,11,12,13,14].…”

Section: Introductionmentioning

confidence: 99%

Defect Creation in the Root of Single-Crystalline Turbine Blades Made of Ni-Based Superalloy

et al. 2019

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An analysis of the defects in the vicinity of the selector–root connection plane occurring during the creation of single-crystalline turbine blades made of CMSX-6 Ni-based superalloy was performed. X-ray diffraction topography, scanning electron microscopy, and positron annihilation lifetime spectroscopy were used. Comparing the area of undisturbed axial growth of dendrites to the area of lateral growth concluded that the low-angle boundaries-like (LAB-like) defects were created in the root as a result of unsteady-state lateral growth of some secondary dendrite arms in layers of the root located directly at the selector–root connection plane. Additional macroscopic low-angle boundaries (LABs) with higher misorientation angles were created as a result of concave curvatures of liquidus isotherm in platform-like regions near selector–root connections. Two kinds of vacancy-type defects, mono-vacancies and vacancy clusters, were determined in relation to the LABs and LAB-like defects. Only mono-vacancies appeared in the areas of undisturbed axial growth. Reasons for the creation of macroscopic LABs and LAB-like defects, and their relationships with vacancy-type defects were discussed.

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“…where, A c is the porosity function, A mush is the mushy zone constant, ε is a small computational constant (0.001) to prevent division by zero. For more governing equations for solute distribution, please see our previous work [24]. Radiative transfer equation: the radiative transfer equation is solved for a set of n different directions, → S i , i = 1, 2, .…”

Section: Continuity Equationmentioning

confidence: 99%

Numerical Simulation of Transport Phenomena in Directional Solidification Castings with Changeable Cross-Section and Solidification Interface Control

Zhang

Zhu

Jiang

et al. 2022

Metals

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The roles of traveling magnetic fields (TMFs) within the transport phenomena during the directional solidification of nickel-based superalloys were simulated. The evolution of thermal field, flow field and solid-liquid interface morphology during the solidification process under both natural and forced convection conditions were also simulated and compared. The strength of TMFs window that suppresses the flow of the interfacial front in the melt was quantified. The association between flow velocity at the interface front and defect formation was discussed.

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Effects of convection patterns on freckle formation of directionally solidified Nickel-based superalloy casting with abruptly varying cross-sections

Cited by 19 publications

References 33 publications

Recent Advancements in the Field of Ni‐Based Superalloys

Recent Advancements in the Field of Ni‐Based Superalloys

Defect Creation in the Root of Single-Crystalline Turbine Blades Made of Ni-Based Superalloy

Numerical Simulation of Transport Phenomena in Directional Solidification Castings with Changeable Cross-Section and Solidification Interface Control

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