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Full-Text Articles in Metallurgy

Thermo-Fluid Characterizations Of The Powder-Bed Fusion Additive Manufacturing Processes Using Laser And Electron Beam, M Shafiqur Rahman Dec 2020

Thermo-Fluid Characterizations Of The Powder-Bed Fusion Additive Manufacturing Processes Using Laser And Electron Beam, M Shafiqur Rahman

University of New Orleans Theses and Dissertations

The powder-bed fusion (PBF) process is a subdivision of Additive Manufacturing (AM) technology where a heat source at a controlled speed selectively fuses regions of a powder-bed material to form three-dimensional (3-D) parts. Two of the most effective PBF processes are selective laser melting (SLM) and electron beam additive manufacturing (EBAM), which can fabricate full-density metallic parts in a layer-by-layer fashion. In this study, thermal behavior and melt-pool dynamics in the PBF process are investigated by developing 3-D multiphysics-based thermo-fluid models for both SLM and EBAM, containing Ti-6Al-4V alloy as a powder-bed material. The laser and electron beams are modeled …


Modeling And Analysis For Unit Cell Size, Material Anisotropy And Material Imperfection Effects Of Cellular Structures Fabricated By Powder Bed Fusion Additive Manufacturing., Yan Wu Dec 2020

Modeling And Analysis For Unit Cell Size, Material Anisotropy And Material Imperfection Effects Of Cellular Structures Fabricated By Powder Bed Fusion Additive Manufacturing., Yan Wu

Electronic Theses and Dissertations

Cellular structures are networks of interconnected struts or walls with porosities and are widely found in many natural load-bearing structures such as plants and bones. Cellular structures offer unique functional characteristics such as high stiffness to weight ratio, tailorable heat transfer coefficient, and enhanced mechanical energy absorption, which makes them highly attractive in various engineering disciplines such as biomedical implants, electrodes, heat exchangers, and lightweight structures. There exists an abundance of literatures that have investigated various mechanical properties of various cellular structures such as Poisson’s ratio, elastic modulus, ultimate strength, yield strength, and failure characteristics. Based on the classic cellular …


Cracking And Earing Phenomenon In Deep-Drawn Stainless Steel Alloys: Role Of Transformation Kinetics, Microstructure, And Texture, Peijun Hou Aug 2020

Cracking And Earing Phenomenon In Deep-Drawn Stainless Steel Alloys: Role Of Transformation Kinetics, Microstructure, And Texture, Peijun Hou

Doctoral Dissertations

The enhancement of formability of advanced high-strength TRIP-assisted steel alloys is a challenging assignment for industrial application due to the cracking phenomenon. The critical factor governing the cracking behavior is residual-stress concentration resulting from the inhomogeneous plastic deformation and microstructural evolution during the forming processes. Martensitic phase transformation kinetics, constituent phases, and crystallographic texture in TRIP-assisted steel alloys are correlated to the microstructure evolution, resulting in phase-specific stress concentration. In the current study, we are aiming at understanding the fundamental mechanisms responsible for the cracking phenomenon and thus improving the formability of TRIP-assisted steel alloys. Four stainless steel (SS) alloys …


Selective Laser Melting 17-4 Ph Stainless Steel And The Effect Of Varied Thermal Treatments On Fatigue Behavior., Sean Daniel Dobson May 2020

Selective Laser Melting 17-4 Ph Stainless Steel And The Effect Of Varied Thermal Treatments On Fatigue Behavior., Sean Daniel Dobson

Electronic Theses and Dissertations

Fatigue failure is the leading source of loss in industry. In order for new means of manufacturing to move towards mainstream use a complete understanding of material and mechanical behavior must be gained. This endeavor seeks to aide in that task by observing the fatigue behavior of selective laser melting (SLM) additive manufacturing (AM) specimens and the effect of differing thermal treatment conditions for an optimized AM process. Stainless steel 17-4 PH specimens were fabricated using SLM AM and thermally treated to three conditions: as-built, solutionized and hardened, and direct hardened. These specimens were characterized for material (powder quality, density, …


Materials-Processing Relationships For Metal Fused Filament Fabrication Of Ti-6al-4v Alloy., Paramjot Singh May 2020

Materials-Processing Relationships For Metal Fused Filament Fabrication Of Ti-6al-4v Alloy., Paramjot Singh

Electronic Theses and Dissertations

Additive manufacturing (AM) is at the mainstream to cater the needs for rapid tooling and small-scale part production. The metal AM of complex geometries is widely accepted and promoted in the industry. While several metal AM technologies exist and are matured to a level where expectation in terms of design and properties are possible to realize. But the metal AM suffers from the heavy expense to acquire equipment, isotropic property challenges, and potential hazards to work with loose reactive metal powder. With this motivation, the dissertation aims to develop the fundamental aspects to print metal parts with bound Ti-6Al-4V powder …


Very High Cycle Fatigue Behavior Of Laser Beam-Powder Bed Fused Inconel 718 Considering The Layer Orientation And Surface Finish Effects, Palmer Frye Jan 2020

Very High Cycle Fatigue Behavior Of Laser Beam-Powder Bed Fused Inconel 718 Considering The Layer Orientation And Surface Finish Effects, Palmer Frye

UNF Graduate Theses and Dissertations

Additive Manufacturing (AM) techniques have recently gained popularity for fabrication of parts used in aerospace applications. Some of these parts may be subjected to cyclic loading at very high frequencies, leading to service life requirements exceeding ten-million cycles (>107 cycles). Therefore, understanding the very high-cycle fatigue (VHCF) behavior of these AM parts is an important step in their design and qualification processes. In this thesis, both high-cycle fatigue (HCF) and VHCF behaviors of Inconel 718, a Ni-base superalloy, manufactured via a Laser Beam-Powder Bed Fusion (LB-PBF) process, are investigated. Uniaxial, fully reversed force-controlled fatigue tests were conducted utilizing …


Table Top Dome Tester, Travis Bernard, Sarah Kassinger, Amanda O'Reilly, Scott Salerno Jan 2020

Table Top Dome Tester, Travis Bernard, Sarah Kassinger, Amanda O'Reilly, Scott Salerno

Williams Honors College, Honors Research Projects

The Erichsen Cupping Test was used as a basis to design a dome tester. The intention of a dome tester is to test sheet metal material properties in all directions. This was done by clamping a piece of sheet metal and using a piston and hydraulic press to punch through the material. The force used to punch the material and the height of the deforming material can be gathered and the sheet metal properties can then be calculated. At the end of the project the team was able to successfully design and manufacture a hydraulic dome tester. However, due to …


Tabletop Mechanical Tester, Jamie Dombroski, Brian English, Richard Leffler, Andrew Shirk Jan 2020

Tabletop Mechanical Tester, Jamie Dombroski, Brian English, Richard Leffler, Andrew Shirk

Williams Honors College, Honors Research Projects

The need for hands-on and face-to-face experiences in the engineering classroom is very great. The equations, principles, and concepts can all be learned, but without the visual and tactile application, these don’t always sink in or become concrete. A small-scale tensile test machine was designed, sourced, manufactured, and tested for the purpose of being applied in classroom settings to provide this experience to engineering students. Extensive research was performed concerning tensile machines on the market, the essential elements of which are the load cell, grips, crosshead, extensometer, motor, and frame. The raw materials for the frame were purchased and drawings …


Jominy Hardenability Tester With In-Situ Heating, Luke Allen Jan 2020

Jominy Hardenability Tester With In-Situ Heating, Luke Allen

Williams Honors College, Honors Research Projects

This project centers on building a Jominy Hardenability tester with In-Situ heating for the manufacturing lab at the University of Akron. A new process and setup will be designed using engineering concepts in order to make the testing more efficient and safer for the teaching and testing of metal hardness. The current Jominy testing setup has efficiency issues within the transfer of specimen from induction heater to testing rig. Our design will simplify the design by creating a test rig that removes the traveling aspect of the specimen which will limit the amount of premature cooling done and will be …