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Articles 1 - 11 of 11
Full-Text Articles in Metallurgy
Effect Of Wall Movement On Porosity Formation In Ductile Iron Castings Under Varying Processing Parameters, Shamsul Alam
Effect Of Wall Movement On Porosity Formation In Ductile Iron Castings Under Varying Processing Parameters, Shamsul Alam
College of Graduate Studies: Theses & Dissertations
Shrinkage porosity is a major defect that significantly impairs the mechanical properties and overall performance of ductile iron castings. Although graphite formation during solidification induces volumetric expansion, this expansion alone is insufficient to fully compensate for the shrinkage occurring throughout solidification. During the solidification and cooling of ductile iron, multiple phase transformations occur, resulting in dynamic volume changes that exert pressure on mold walls and internal cavities. These pressures can deform mold walls and casting surfaces, leading to defects such as swell and porosity, while also influencing shrinkage formation. This study aims to analyze the mechanisms of porosity formation and …
Effects Of Composition, Nodularity, Pouring Temperature, Inoculation, And Mold Strength On Wall-Movement In Sgi Castings During Solidification And Cooling, Noah Brack
College of Graduate Studies: Theses & Dissertations
The iron-carbon casting alloy known as spheroidal graphite iron (SGI), nodular graphite iron, or ductile iron (DI) experiences complex volume changes during its solidification and cooling as graphite nodules and austenite form. These volume changes result in forces on the mold cavity walls and can deform the mold walls in cases when mold walls lack the strength to resist the deformation. This wall movement can cause the formation of casting defects such as swell, warped part geometry, and shrinkage porosity. Though this phenomenon has been studied in the past, it remains difficult to predict casting wall movement with existing data. …
Effect Of Elemental Additions On The Microstructure, Macrostructure, And Mechanical Properties Of Gray Iron, August E. Rautmann
Effect Of Elemental Additions On The Microstructure, Macrostructure, And Mechanical Properties Of Gray Iron, August E. Rautmann
College of Graduate Studies: Theses & Dissertations
Gray iron is composed primarily of an iron matrix and flake graphite, with the higher percentage of volume taken up by the iron matrix. The iron matrix is the transformation product of austenite, and this prior austenite structure is understood to affect the final grain structure. Grain structure affects the properties of a metal, with a finer structure recognized as beneficial for most properties. Thus, the refinement of austenite structure has potential in improving the material properties of gray iron. This study aims to advance the limited knowledge about the control of austenite grain size via elemental additions. Building off …
Effect Of Alloying Additions On Austenite Refinement In Nickel-Alloyed Ductile Cast Irons, Adnan Adib Aahamed
Effect Of Alloying Additions On Austenite Refinement In Nickel-Alloyed Ductile Cast Irons, Adnan Adib Aahamed
College of Graduate Studies: Theses & Dissertations
The benefits associated with the application of ductile irons are significantly attributed to the control of microstructures, with refinement of austenitic matrix during solidification playing a significant role. Nickel alloyed ductile irons are attractive due to their potential for high ductility and suitability for potential high-temperature applications with stable austenitic microstructure. Refinement of austenite grain structure is thus important to enhance the mechanical properties of the alloyed ductile iron. This research investigates the impact of in-mold additions of different alloying elements on the austenite morphology and grain refinement of nickel-alloyed ductile iron along with the associated mechanical properties. A hypoeutectic …
Pulsed Arc Additive Manufacturing Of A Functionally Graded Er2209 Duplex Stainless Steel And Hsla-100 Structure: Morphology, Characterization, And Mechanical Performance, Stevens G. Hill Jr
Pulsed Arc Additive Manufacturing Of A Functionally Graded Er2209 Duplex Stainless Steel And Hsla-100 Structure: Morphology, Characterization, And Mechanical Performance, Stevens G. Hill Jr
College of Graduate Studies: Theses & Dissertations
Wire arc additive manufacturing is a process well suited to the efficient production of large structures. Duplex stainless steel exhibits high corrosion resistance and good strength which can be highly beneficial for industrial use. However, its use is limited due to its cost and complexity in controlling microstructure to achieve desired properties. In many cases, it can be highly beneficial to manufacture a component which uses specialty steel grades such as duplex stainless steel only where necessary, and utilizes more affordable, commonly available steels for reinforcement or bulk structural support. A functionally graded material satisfies these requirements by providing a …
Experimental Investigation Of Liquid Metal Embrittlement In Hot-Dip Galvanized Structural Steel, Amelia Mcnamee
Experimental Investigation Of Liquid Metal Embrittlement In Hot-Dip Galvanized Structural Steel, Amelia Mcnamee
College of Graduate Studies: Theses & Dissertations
This research investigated the liquid metal embrittlement (LME) of hot-dipped galvanized structural steel. The relationship between stress and failure time was analyzed to evaluate the potential presence of a critical stress threshold beyond which LME may occur. A testing apparatus to induce axial stress was designed and assembled in-house. A36 low carbon steel was tested in this study. Different deadweight loadings were applied to the testing sample along the axial direction. The test temperature was maintained by a programmable furnace while the sample gauge section was submerged in a molten zinc bath. Failure time and total displacement of the steel …
Effects Of Additions On The Microstructure, Macrostructure, And Mechanical Properties Of Gray Iron, Evan J. Carter
Effects Of Additions On The Microstructure, Macrostructure, And Mechanical Properties Of Gray Iron, Evan J. Carter
College of Graduate Studies: Theses & Dissertations
The iron matrix is a major component of the gray iron (GI) microstructure, which is the transformation product of austenite during solidification. It is generally accepted that the structure of the austenite will impact the final grain structure and thus the properties of GI. Refinement of the austenite grain structure has the potential to increase the strength of GI. Knowledge of controlling austenite grain size with common alloy additions in GI is very limited and is investigated in this research. Utilizing the DAAS heat treatment process, the austenite grain boundaries can be retained and observed directly. The observations were correlated …
Design And Fabrication Of A High-Performance Heat Exchanger Using An Optimized Three-Dimensional Surface Structure Through Additive Manufacturing, Seth T. Waters
College of Graduate Studies: Theses & Dissertations
A heat exchanger is a device used to transfer thermal energy between two intertwining fluid pathways. In this study, the design of a novel heat exchanger is proposed using functional gradient double gyroid structure. The complex internal geometries of the gyroid structure significantly increases the surface area to volume ratio, and potentially could expressively improve efficiency of the heat transfer. The proposed idea provides a new approach for the design of a high-efficiency heat exchanger. In order to fabricate the complex structured heat exchanger system additive manufacturing is adapted instead of traditionally subtractive manufacturing techniques or casting. The prototypes of …
Effects Of Titanium And Cerium Addition On Grain Size And Mechanical Properties Of Ductile Iron Castings, Shelton F. Fowler Iv
Effects Of Titanium And Cerium Addition On Grain Size And Mechanical Properties Of Ductile Iron Castings, Shelton F. Fowler Iv
College of Graduate Studies: Theses & Dissertations
According to the Hall-Petch equation, the refinement of grains in metals increases the yield strength of the material. Austenite grain size influences the fineness of microstructural constituents in the ferrous alloys. It is well studied that cerium and titanium refine the austenite in steels and some gray irons, but no studies have been done to systematically explore the effects of cerium and titanium additions on austenite in ductile iron. This study sought to determine the effects of selected levels of these elements on the grain size within ductile iron. A hypoeutectic iron was chosen for testing as the proeutectic phase …
A Study Of Reduced Activation Ferritic Martensitic Metal Core Wire For Wire Arc Additive Manufacturing, Alexander L. Reichenbach
A Study Of Reduced Activation Ferritic Martensitic Metal Core Wire For Wire Arc Additive Manufacturing, Alexander L. Reichenbach
College of Graduate Studies: Theses & Dissertations
This study seeks to determine the technical feasibility of fabricating reduced activation ferritic martensitic (RAFM) steel parts, using a wire arc additive manufacturing (WAAM) process. The WAAM process, manufactures a part by depositing layers of metal onto a substrate to build a large scale near net shape part. RAFM alloy steels are next generation steels designed to resist radiation effects in the radiation intense working environments, such as nuclear reactors. To achieve this, process development and testing to design the WAAM production process with the custom RAFM filler wire was carried out. Several welding waveform modes were tested, and it …
Examination Of Early Stage Grey Iron Solidification Through The Development Of Fast-Quench Methodology, James C. Liggett
Examination Of Early Stage Grey Iron Solidification Through The Development Of Fast-Quench Methodology, James C. Liggett
Honors College Theses
As grey iron casting accounts for a significant share of the foundry industry, proper understanding of the effects of solidification and growth mechanisms on the mechanical properties of grey iron is crucial. Prior experimentation has been performed examining early stage solidification and growth of the carbon phase of ductile iron, in which rapid quench samples are obtained which detail austenite-graphite interactions during solidification. This prior experimentation is built upon in though this research and applied to examine the early stage growth of flake graphite in grey iron. The purpose of this research is to validate a proposed fast-quench method by …