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Articles 1 - 30 of 135
Full-Text Articles in Engineering
Calibration Of The Johnson–Cook Model At High Temperatures For An Ultra-High Strength Crnimov Steel, Mario F. Buchely, S. Chakraborty, V. Athavale, Laura Bartlett, Ronald J. O'Malley, D. Field, K. Limmer, K. Sebeck
Calibration Of The Johnson–Cook Model At High Temperatures For An Ultra-High Strength Crnimov Steel, Mario F. Buchely, S. Chakraborty, V. Athavale, Laura Bartlett, Ronald J. O'Malley, D. Field, K. Limmer, K. Sebeck
Materials Science and Engineering Faculty Research & Creative Works
This paper presents a study on the thermo-mechanical behavior of an ultra-high strength CrNiMoV steel at high temperatures and medium strain rates through hot tensile tests. The material was examined in two conditions: as-cast/heat-treated (AC/HT) and as-rolled (AR). Tensile tests were conducted at temperatures of 800,900,1000,1100, and 1200°C, and strain rates of 0.1,1, and 10s−1. Inclusion and porosity analysis was also performed on the tensile specimens. The results revealed that the flow stress decreased by approximately 70% on average from 800°C to 1200°C, while increasing by approximately 32% on average from 0.1s−1 to 10s−1 in strain rate. The elongation exhibited …
Engineering Heterogeneous Nucleation During Solidification Of Multiphase Cast Alloys: An Overview, Simon (Semen) N. Lekakh, Jingjing Qing
Engineering Heterogeneous Nucleation During Solidification Of Multiphase Cast Alloys: An Overview, Simon (Semen) N. Lekakh, Jingjing Qing
Materials Science and Engineering Faculty Research & Creative Works
The theory of heterogeneous nucleation was initially developed as a part of condensed matter physics, and later it was used as an important engineering tool to design metallurgical processes. This success has led to wide applications of the theory in metallurgical practice. For example, engineering heterogeneous nucleation in ductile iron has been used to reduce shrinkage defects, suppress cementite formation, and modify the size and shape of microstructural constituencies. This demonstrates how theoretical knowledge could benefit industry practice. This overview aims to summarize the authors' published studies in co-authorship with colleagues and students, which covers different aspects of engineering heterogeneous …
Effect Of Cr And Ni Concentrations On Resilience Of Cast Nb-Alloyed Heat Resistant Austenitic Steels At Extreme High Temperatures, Simon N. Lekakh, Mario F. Buchely, Mei Li, Larry Godlewski
Effect Of Cr And Ni Concentrations On Resilience Of Cast Nb-Alloyed Heat Resistant Austenitic Steels At Extreme High Temperatures, Simon N. Lekakh, Mario F. Buchely, Mei Li, Larry Godlewski
Materials Science and Engineering Faculty Research & Creative Works
Austenitic Cr–Ni Alloyed Heat Resistant Steels with Nb Additions Are Used for Intensively Thermo-Mechanically Loaded Cast Components Working in Extreme High Temperature Oxidizing Environment. their Performance during Static Oxidation and Transient Thermo-Mechanical Loading Was Investigated to Recommend an Optimal Cost-Effective Cr/Ni Composition of Nb-Alloyed Austenitic Class Steels. the Static Oxidation and Transient Thermo-Mechanical Behavior of Three Austenitic Steels with Different Cr/Ni Alloying Levels Were Investigated and Compared for Variety of Working Conditions. Static Oxidation Was Performed between 900 °C and 1000 °C in Air for 400 H. the Critical Temperature Which Increases Spallation during Static Oxidation Was Determined for Each …
Microstructure Evolution And Austenitic Grain Refinement Of Ti-Modified High Mn Steels During Solution Annealing Heat Treatment, Abhinav Karanam, Arnab Sarkar, Erik Nenzen, Viraj Ashok Athavale, Mark Watson, Laura Nicole Bartlett, Lukas Bichler
Microstructure Evolution And Austenitic Grain Refinement Of Ti-Modified High Mn Steels During Solution Annealing Heat Treatment, Abhinav Karanam, Arnab Sarkar, Erik Nenzen, Viraj Ashok Athavale, Mark Watson, Laura Nicole Bartlett, Lukas Bichler
Materials Science and Engineering Faculty Research & Creative Works
Austenitic high manganese (Mn) steels are often used in harsh environments due to their high toughness and wear resistance. Heat treatments are performed to engineer the microstructure of the steels and optimize their performance for the desired service conditions. This study investigated the effect of titanium (Ti) and heat treatment on the microstructure of cast high Mn steel (HMS) alloys. The results reveal that Ti addition contributed to grain refinement in the as cast and heat-treated conditions. In-situ observation of microstructure evolution up to 1125 °C confirmed the stability of precipitated TiC particles, while revealing a new mechanism of grain …
Performance Evaluation Of Composite Sandwich Structures With Additively Manufactured Aluminum Honeycomb Cores With Increased Bonding Surface Area, M. Rangapuram, S. K. Dasari, Joseph William Newkirk, K. Chandrashekhara, H. Misak, P. R. Toivonen, D. Klenosky, T. Unruh, J. Sam
Performance Evaluation Of Composite Sandwich Structures With Additively Manufactured Aluminum Honeycomb Cores With Increased Bonding Surface Area, M. Rangapuram, S. K. Dasari, Joseph William Newkirk, K. Chandrashekhara, H. Misak, P. R. Toivonen, D. Klenosky, T. Unruh, J. Sam
Materials Science and Engineering Faculty Research & Creative Works
Modern aerostructures, including wings and fuselages, increasingly feature sandwich structures due to their high-energy absorption, low weight, and high flexural stiffness. The face sheet of these sandwich structures are typically thin composite laminates with interior honeycombs made of Nomex or aluminum. Standard cores are structurally efficient, but their design cannot be varied throughout the structure. With additive manufacturing (AM) technology, these core geometries can be altered to meet the design requirements that are not met in standard honeycomb cores. This study used a modified aluminum honeycomb core, with increased surface area on the top and bottom, as the core material …
Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk
Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …
Compositional Modifications To Alter And Suppress Laves Phases In Alxcrmotayti Alloys, Austin E. Mann, Joseph William Newkirk
Compositional Modifications To Alter And Suppress Laves Phases In Alxcrmotayti Alloys, Austin E. Mann, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
Herein, the Development of Refractory Complex Concentrated Alloys in the Al–Cr–Mo–Ta–Ti Alloy System is Reported. Alloys with Modified Al and Ta Concentrations Are Designed using CALPHAD Tools and Produced Via Arc Melting and Characterized in Both As-Cast and Annealed Forms. Properties of the Alloys, Nature of the Microstructures, and Phase Transformation Behavior Are Described Via X-Ray Diffraction, Microstructural Characterization, Microhardness, and Differential Scanning Calorimetry. Two Alloys, Namely, Al0.25CrMoTa0.8Ti and Al0.75CrMoTa0.8Ti, Are Represented by a Body-Centered-Cubic Matrix Phase after Annealing, along with a Secondary Cr–Ta Laves Phase of the C15 and C14 Polytypes, respectively. in As-Cast and Annealed Forms, the Al0.75CrMoTa0.45Ti …
A Study On The Impact Of Silicon And Manganese On Peritectic Behavior In Low Alloy Steels Assisted By Mold Thermal Mapping Technology And Shell Growth Measurements, Damilola Balogun, Muhammad Roman, Rex E. Gerald, Laura Bartlett, Jie Huang, Ronald O'Malley
A Study On The Impact Of Silicon And Manganese On Peritectic Behavior In Low Alloy Steels Assisted By Mold Thermal Mapping Technology And Shell Growth Measurements, Damilola Balogun, Muhammad Roman, Rex E. Gerald, Laura Bartlett, Jie Huang, Ronald O'Malley
Materials Science and Engineering Faculty Research & Creative Works
Non-Uniform Shell Growth Commonly Caused by the Peritectic Transformation in Low Carbon and Low Alloy Steels Has Been Directly Correlated with Mold Thermal Maps using a Mold Immersion Test into a Molten Steel Alloy. Mold Thermal Maps Were Obtained by Performing Real-Time Temperature Measurements with Optical Fibers Embedded 1 Mm from the Mold Working Surface. Shell Growth Measurements Were Obtained by 3D Optical Scanning of the Recovered Steel Shell Following Immersion Testing. the Effects of Silicon and Manganese on the Shell Growth and Mold Temperature Maps Have Been Examined in Relation to the Peritectic Transformation for Varying Carbon Contents. Results …
Phenomenological Analysis Of Surface Degradation Of Metallic Materials In Extreme Environment, Simon N. Lekakh, Oleg Neroslavsky
Phenomenological Analysis Of Surface Degradation Of Metallic Materials In Extreme Environment, Simon N. Lekakh, Oleg Neroslavsky
Materials Science and Engineering Faculty Research & Creative Works
The resistance to surface degradation in metallic alloys plays an important role for the lifetime of the components working in harsh environments. The mechanisms involved in degradation of metallic surface in a high-temperature aggressive gaseous atmosphere include the following: forming adherent to the surface multiphase oxide layer, partial spallation, and possible vaporization of formed compounds. The governing equation, which describes a parabolic growth of adherent layer, time-dependent vaporization, and cross-linked to instantaneous thickness of adherent layer spallation rate, was suggested and analyzed. The several relationships between the kinetic constants were defined from analysis of the governing equation. Design of routes …
Residual Stress Distribution, Distortion, And Crack Initiation In Conventional And Intensive Quench Practices, Kingsley Tochukwu Amatanweze, Mario F. Buchely, Viraj Ashok Athavale, Laura Bartlett, Ronald J. O'Malley, Toshi Suzuki
Residual Stress Distribution, Distortion, And Crack Initiation In Conventional And Intensive Quench Practices, Kingsley Tochukwu Amatanweze, Mario F. Buchely, Viraj Ashok Athavale, Laura Bartlett, Ronald J. O'Malley, Toshi Suzuki
Materials Science and Engineering Faculty Research & Creative Works
This study evaluates the effect of two different quench practices on distortion, sensitivity to quench cracking, development and distribution of residual stress, microstructural uniformity, and hardenability of standardized test castings. Navy C-rings made of AISI 4340 were quenched in this experiment. Some rings were quenched in a conventional draft tube immersion quench bath, and others were quenched in an intensive quench spray system to compare with the results from the conventional immersion quench bath. The rings were measured with a coordinate measuring machine, for distortion and flatness, before and after quenching. Hardness profiles of the quenched rings showed through hardness …
Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk
Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …
Advancing Aluminum Casting Optimization With Real-Time Temperature And Gap Measurements Using Optical Fiber Sensors At The Metal-Mold Interface, Bohong Zhang, Abhishek Prakash Hungund, Dinesh Reddy Alla, Deva Prasaad Neelakandan, Muhammad Roman, Ronald J. O'Malley, Laura Bartlett, Rex E. Gerald, Jie Huang
Advancing Aluminum Casting Optimization With Real-Time Temperature And Gap Measurements Using Optical Fiber Sensors At The Metal-Mold Interface, Bohong Zhang, Abhishek Prakash Hungund, Dinesh Reddy Alla, Deva Prasaad Neelakandan, Muhammad Roman, Ronald J. O'Malley, Laura Bartlett, Rex E. Gerald, Jie Huang
Materials Science and Engineering Faculty Research & Creative Works
Accurate measurement of interfacial heat transfer during casting solidification is crucial for optimizing metal solidification processes. The gap between the mold wall and the casting surface plays a significant role in heat transfer and cooling rates. In this study, two innovative fiber-optic sensors are employed to measure real-time mold gaps and thermal profiles during the solidification of A356 aluminum in a permanent mold casting. The experimental setup consists of a specially designed mold system made of unheated, uncoated tool steel, which facilitates easy installation of the fiber-optic sensors. An Extrinsic Fabry-Perot interferometric (EFPI) sensor is utilized to monitor the evolving …
Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou
Tini-Based Bi-Metallic Shape-Memory Alloy By Laser-Directed Energy Deposition, Yitao Chen, Cesar Ortiz Rios, Braden Mclain, Joseph William Newkirk, Frank W. Liou
Materials Science and Engineering Faculty Research & Creative Works
In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti-Ni-Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend was used for raw materials. Various material characterization approaches were applied to reveal different material properties in two sections. The as-fabricated Ti-Ni-Cu alloy microstructure has the TiNi phase as the matrix with Ti2Ni secondary precipitates. The hardness shows no high values indicating that the major phase is not hard intermetallics. A bonding strength of 569.1 MPa …
Effect Of Micro-Structural Dispersity Of Simo Ductile Iron On High Temperature Performance During Static Oxidation, Semen Naumovich Lekakh, Asebi Bofah, Larry A. Godlewski, Mei Li
Effect Of Micro-Structural Dispersity Of Simo Ductile Iron On High Temperature Performance During Static Oxidation, Semen Naumovich Lekakh, Asebi Bofah, Larry A. Godlewski, Mei Li
Materials Science and Engineering Faculty Research & Creative Works
High silicon and molybdenum (SiMo) ductile iron is commonly used for car exhaust systems, and its micro-structural dispersity depends on intrinsic parameters, which include alloy composition and inoculation efficiency, as well as extrinsic factors, such as casting wall thickness and molding material, which define cooling rate during solidification. Micro-structural dispersity is referred to as the degree of heterogeneity of sizes of structural constituencies within the microstructure. A variation in the micro-structural dispersity could impact the high temperature performance of SiMo ductile iron during static oxidation and transient thermo-mechanical loading conditions. In this study, static high temperature tests were performed on …
Effects Of Carrier, Leveller, And Booster Concentrations On Zinc Plating From Alkaline Zincate Baths, Abdul Jalil Mohammed, Michael S. Moats
Effects Of Carrier, Leveller, And Booster Concentrations On Zinc Plating From Alkaline Zincate Baths, Abdul Jalil Mohammed, Michael S. Moats
Materials Science and Engineering Faculty Research & Creative Works
Organic additives are required for alkaline zincate plating baths to obtain an acceptable coating on steel for corrosion protection. The effects and possible interactions of three commercial additives (Eldiem Carrier, Eldiem Booster, and Bright Enhancer 2x on zinc electrodeposition from a high-concentration alkaline zincate bath were investigated. Visually acceptable deposits were produced within the current density range of 130 to 430 A m-2 for most additive conditions examined. Over concentration ranges examined, decreasing the booster concentration led to brighter zinc deposits, and an interaction between the carrier and the booster was detected. The additives fostered the formation of compact …
Control Of High-Temperature Static And Transient Thermomechanical Behavior Of Simo Ductile Iron By Al Alloying, Semen Naumovich Lekakh, Catherine E. Johnson, L. Godlewski, Mei Li
Control Of High-Temperature Static And Transient Thermomechanical Behavior Of Simo Ductile Iron By Al Alloying, Semen Naumovich Lekakh, Catherine E. Johnson, L. Godlewski, Mei Li
Materials Science and Engineering Faculty Research & Creative Works
Silicon and molybdenum (SiMo) ductile iron is commonly used for exhaust manifolds because these components experience thermal cycling in oxidizing environment, which requires resistance to fatigue during transient thermomechanical loads. Previous studies have demonstrated that alloying elements, such as Al, to SiMo ductile iron reduces the amount of surface degradation during static high-temperature exposure. However, deterioration of sphericity of the graphite nodules and a decrease in ductility could affect the tendency of cracking during thermal cycling. In this article, the effect of Al alloying on static and transient thermomechanical behavior of SiMo ductile iron was investigated to optimize the amount …
Fabricating Tinicu Ternary Shape Memory Alloy By Directed Energy Deposition Via Elemental Metal Powders, Yitao Chen, Xinchang Zhang, Mohammad Masud Parvez, Joseph William Newkirk, Frank W. Liou
Fabricating Tinicu Ternary Shape Memory Alloy By Directed Energy Deposition Via Elemental Metal Powders, Yitao Chen, Xinchang Zhang, Mohammad Masud Parvez, Joseph William Newkirk, Frank W. Liou
Materials Science and Engineering Faculty Research & Creative Works
In this paper, a TiNiCu shape memory alloy single-wall structure was fabricated by the directed energy deposition technique with a mixture of elemental Ti, Ni, and Cu powders following the atomic percentage of Ti50Ni45Cu5 to fully utilize the material flexibility of the additive manufacturing process to develop ternary shape memory alloys. The chemical composition, phase, and material properties at multiple locations along the build direction were studied, using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Vickers hardness test-ing, tensile testing, and differential scanning calorimetry. The location-dependent compositions of martensitic TiNi and austenitic TiNi phases, mechanical properties, and functional properties …
Absorption Of Nitrogen During Pulsed Wave L-Pbf Of 17-4 Ph Steel, Ben Brown, Joseph William Newkirk, Frank W. Liou
Absorption Of Nitrogen During Pulsed Wave L-Pbf Of 17-4 Ph Steel, Ben Brown, Joseph William Newkirk, Frank W. Liou
Materials Science and Engineering Faculty Research & Creative Works
In the fabrication of 17-4 PH by laser powder bed fusion (L-PBF) the well-documented occurrence of large amounts of retained austenite can be attributed to an elevated concentration of nitrogen present in the material. While the effects of continuous wave (CW) laser processing on in-situ nitrogen absorption characteristics have been evaluated, power modulated pulsed wave (PW) laser processing effects have not. In this study the effects of PW L-PBF processing of 17-4 PH on nitrogen absorption, phase composition, and mechanical performance are explored using commercially available PW L-PBF equipment and compared to samples produced by CW L-PBF. PW L-PBF samples …
Thermodynamic Prediction And Experimental Verification Of Multiphase Composition Of Scale Formed On Reheated Alloy Steels, Richard Osei, Semen Naumovich Lekakh, Ronald O'Malley
Thermodynamic Prediction And Experimental Verification Of Multiphase Composition Of Scale Formed On Reheated Alloy Steels, Richard Osei, Semen Naumovich Lekakh, Ronald O'Malley
Materials Science and Engineering Faculty Research & Creative Works
The structure, phase, and composition of scale formed on a continuously cast steel slab during reheating depend on intrinsic factors (steel chemistry, microstructure, and as-cast surface condition) and extrinsic parameters (temperature, time, composition, and velocity of combustion gas atmosphere). The scale that forms on a slab normally has several layers with differing compositions and phases and knowledge of this scale structure is important in subsequent descaling and hot rolling processing steps. Formation of multiphase scale structures on steel during high temperature oxidation in reheat furnace proceeds according to a local thermodynamic equilibrium, while thickness of layers depends on kinetic conditions …
Optimization And Characterization Of Novel Injection Molding Process For Metal Matrix Syntactic Foams, Myranda Spratt, Joseph William Newkirk
Optimization And Characterization Of Novel Injection Molding Process For Metal Matrix Syntactic Foams, Myranda Spratt, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
Metal matrix syntactic foams are particulate composites comprised of hollow or porous particles embedded in a metal matrix. These composites are difficult to manufacture due primarily to the lightweight, relatively fragile filler material. In this work, an injection molding process was developed for metal matrix syntactic foams. First, an aqueous binder was optimized for low-pressure injection molding. A mixture model was used to optimize the composition of the binder to achieve the highest relative density. The model predicted the maximum relative density was at a binder composition (in vol.%) of 7% agar, 4% glycerin, and 89% water. Second, this binder …
Microstructural Influence On Mechanical Properties Of A Lightweight Ultrahigh Strength Fe-18mn-10al-0.9c-5ni (Wt%) Steel, Michael Piston, Laura Bartlett, Krista R. Limmer, Daniel M. Field
Microstructural Influence On Mechanical Properties Of A Lightweight Ultrahigh Strength Fe-18mn-10al-0.9c-5ni (Wt%) Steel, Michael Piston, Laura Bartlett, Krista R. Limmer, Daniel M. Field
Materials Science and Engineering Faculty Research & Creative Works
This study evaluates the role of thermomechanical processing and heat treatment on the microstructure and mechanical properties of a hot rolled, annealed, and aged Fe-18Mn-10Al-0.9C-5Ni (wt%) steel. The steel exhibited rapid age hardening kinetics when aged in the temperature range of 500-600 ⁰C for up to 50 h, which has been shown in other work to be the result of B2 ordering in the ferrite and K-carbide precipitation within the austenite matrix. The ultimate tensile strength increased from 1120 MPa in the annealed condition to 1230 MPa after 2 h of aging at 570 ⁰C. Charpy V-notch toughness was evaluated …
Peritectic Behavior Detection In The Fe-C-Mn-Al-Si Steel System Using Fiber Optic Temperature Mapping, Muhammad Roman, Damilola Balogun, Rex E. Gerald Ii, Laura Bartlett, Jie Huang, Ronald J. O'Malley
Peritectic Behavior Detection In The Fe-C-Mn-Al-Si Steel System Using Fiber Optic Temperature Mapping, Muhammad Roman, Damilola Balogun, Rex E. Gerald Ii, Laura Bartlett, Jie Huang, Ronald J. O'Malley
Materials Science and Engineering Faculty Research & Creative Works
Peritectic reactions can cause surface defects and breakouts in continuous casting and the peritectic region is often avoided by adjusting the chemical composition of the steel to cast outside of the peritectic sensitivity range. However, the combined effects of C, Mn, Al, and Si on the boundaries that map peritectic region are still disputed for many advanced high strength steel grades. An apparatus for performing controlled solidification experiments is being developed to characterize the effects of chemical composition on the uniformity of shell growth during solidification using a copper chill mold with an embedded fiber-optic temperature sensor that enables high …
The Influence Of Ti, Nb And V On The Hot Ductility Of As-Cast Microalloyed Steels, Madhuri Varadarajan, Laura Bartlett, Ronald J. O'Malley, Semen Naumovich Lekakh
The Influence Of Ti, Nb And V On The Hot Ductility Of As-Cast Microalloyed Steels, Madhuri Varadarajan, Laura Bartlett, Ronald J. O'Malley, Semen Naumovich Lekakh
Materials Science and Engineering Faculty Research & Creative Works
Microalloying with Ti, Nb and V, both individually and in combination, is a common method for producing steels with high strength and toughness. However, interaction with other elements and impurities can lead to cracking during continuous casting and rolling. The hot ductility of commercially cast V, Nb and Nb-V-Ti steels has been investigated using two experimental methods: tensile testing utilizing a servo-hydraulic load frame with a resistance furnace and thermomechanical testing using rapid joule heating. The temperature-dependent ductility of these steels is compared for both test methods. Factors that influence the ductility of these steels are discussed.
New Experimental Apparatus To Investigate Hot Tearing Behavior In Steel, Yanru Lu, Laura Bartlett, Ronald J. O'Malley, Semen Naumovich Lekakh, Mario F. Buchely
New Experimental Apparatus To Investigate Hot Tearing Behavior In Steel, Yanru Lu, Laura Bartlett, Ronald J. O'Malley, Semen Naumovich Lekakh, Mario F. Buchely
Materials Science and Engineering Faculty Research & Creative Works
Hot tearing is a complex thermomechanical phenomenon occurring in the semi-solid region. Strain in this region can induce cracking and localized alloying element segregation. An apparatus for investigating hot tearing was developed utilizing a servo-motor controlled cylinder to apply a pre-determined amount of strain to the solidifying shell. A special mold was developed using filling and solidification modeling to ensure that dendrite growth was perpendicular to applied strain. A computer-automated system was utilized to control the strain and strain rate and measure the force and displacement. Solidification experiments utilizing AISI 1020 steel validated the apparatus capabilities and optimized testing parameters.
A Modified Johnson-Cook Model Incorporating The Effect Of Grain Size On Flow Stress, S. Ganguly, Mario F. Buchely, K. Chandrashekhara, Semen Naumovich Lekakh, Ronald J. O'Malley
A Modified Johnson-Cook Model Incorporating The Effect Of Grain Size On Flow Stress, S. Ganguly, Mario F. Buchely, K. Chandrashekhara, Semen Naumovich Lekakh, Ronald J. O'Malley
Materials Science and Engineering Faculty Research & Creative Works
The mechanical properties of steel are influenced by grain size, which can change through mechanisms such as nucleation and growth at elevated temperatures. However, the classic Johnson-Cook model that is widely used in hot deformation simulations does not consider the effect of grain size on flow stress. In this study, the Johnson-Cook model was modified to incorporate the effects of austenite grain size on flow stress. A finite element model was employed to characterize the effects of grain size on the flow stress for different steel grades over a range of temperatures (900⁰ to 1300⁰). Simulation results show good agreement …
Interactions Between Dry Vibratable Tundish Linings And Steel Melts, Tyler M. Richards, Ronald J. O'Malley, Jeffrey D. Smith, Todd P. Sander
Interactions Between Dry Vibratable Tundish Linings And Steel Melts, Tyler M. Richards, Ronald J. O'Malley, Jeffrey D. Smith, Todd P. Sander
Materials Science and Engineering Faculty Research & Creative Works
Interactions between two tundish working linings and molten steel were investigated using industrial samples and laboratory testing. Periclase-based dry vibe linings from two production facilities were sampled and examined after casting: one containing 30 wt.% olivine and one without olivine. Cathodoluminescence imaging, secondary electron microscopy, energydispersive spectroscopy and x-ray diffraction analysis were performed to characterize the interactions. An experiment was developed to replicate the conditions found in a production tundish on the laboratory scale. Results comparing interactions observed in laboratory lining tests and commercial lining samples for the two lining materials are presented and discussed.
Scale Formation On 430 Stainless Steel In A Simulated Slab Combustion Reheat Furnace Atmosphere, Richard Osei, Semen Naumovich Lekakh, Ronald J. O'Malley
Scale Formation On 430 Stainless Steel In A Simulated Slab Combustion Reheat Furnace Atmosphere, Richard Osei, Semen Naumovich Lekakh, Ronald J. O'Malley
Materials Science and Engineering Faculty Research & Creative Works
Scale formed during slab reheating can be difficult to remove by high-pressure descaling, having a negative impact hot roll surface quality. A large-capacity thermogravimetric apparatus that replicates the combustion atmosphere and temperature in a slab reheat furnace was used to investigate scale formation on 430 stainless steel. Effects of reheating parameters (temperature, time and atmosphere) on oxidation kinetics were investigated. Oxidized samples were characterized by scanning electron microscopy, Raman spectroscopy and x-ray diffraction to document the microstructure and morphology of scale. Mechanisms for the formation of multi-layered oxide structures that complicate oxidation kinetics and scale removal are discussed.
A Spatially Distributed Fiber-Optic Temperature Sensor For Applications In The Steel Industry, Muhammad Roman, Damilola Balogun, Yiyang Zuang, Rex E. Gerald Ii, Laura Bartlett, Ronald J. O'Malley, Jie Huang
A Spatially Distributed Fiber-Optic Temperature Sensor For Applications In The Steel Industry, Muhammad Roman, Damilola Balogun, Yiyang Zuang, Rex E. Gerald Ii, Laura Bartlett, Ronald J. O'Malley, Jie Huang
Materials Science and Engineering Faculty Research & Creative Works
This paper presents a spatially distributed fiber-optic sensor system designed for demanding applications, like temperature measurements in the steel industry. The sensor system employed optical frequency domain reflectometry (OFDR) to interrogate Rayleigh backscattering signals in single-mode optical fibers. Temperature measurements employing the OFDR system were compared with conventional thermocouple measurements, accentuating the spatially distributed sensing capability of the fiber-optic system. Experiments were designed and conducted to test the spatial thermal mapping capability of the fiber-optic temperature measurement system. Experimental simulations provided evidence that the optical fiber system could resolve closely spaced temperature features, due to the high spatial resolution and …
Grain Size Effects In Selective Laser Melted Fe-Co-2v, Wesley Everhart, Joseph William Newkirk
Grain Size Effects In Selective Laser Melted Fe-Co-2v, Wesley Everhart, Joseph William Newkirk
Materials Science and Engineering Faculty Research & Creative Works
The material science of additive manufacturing (AM) has become a significant topic due to the unique way in which the material and geometry are created simultaneously. Major areas of research within inorganic materials include traditional structural materials, shape memory alloys, amorphous materials, and some new work in intermetallics. The unique thermal profiles created during selective laser melting (SLM) may provide new opportunities for processing intermetallics to improve mechanical and magnetic performance. A parameter set for the production of Fe-Co-2V material with additive manufacturing is developed and efforts are made to compare the traditional wrought alloy to the AM version of …
Effective Elastic Properties Of Additively Manufactured Metallic Lattice Structures: Unit-Cell Modeling, Okanmisope Fashanu, David Murphy, Myranda Spratt, Joseph William Newkirk, K. Chandrashekhara, Ben Brown, John Porter
Effective Elastic Properties Of Additively Manufactured Metallic Lattice Structures: Unit-Cell Modeling, Okanmisope Fashanu, David Murphy, Myranda Spratt, Joseph William Newkirk, K. Chandrashekhara, Ben Brown, John Porter
Materials Science and Engineering Faculty Research & Creative Works
Lattice structures are lightweight materials, which exhibit a unique combination of properties such as air and water permeability, energy and acoustic absorption, low thermal conductivity, and electrical insulation. In this work, unit-cell homogenization was used to predict the effective elastic moduli of octet-truss (OT) lattice structures manufactured using selective laser melting (SLM). OT structures were manufactured using a Renishaw AM 250 SLM machine with various relative densities. Compression test was carried out at strain rate 5 x 10-3 m-1 using an MTS frame. Finite element analysis was used in the determination of the OT’s effective elastic properties. Results …