Metallurgy Commons^™

Microstructure Control And Correlation To Creep Properties In Grade 91 Steel Weldment After Thermo-Mechanical Treatments And An Fe-30cr-3al Alloy Strengthened By Fe2nb Laves Phase, Benjamin Allen Shassere

Doctoral Dissertations

Type IV cracking in weldments of steel pipes after creep deformation is a concern in modern fossil-fueled power plants. Two possible methods for minimizing or eliminating Type IV cracking will be discussed. The first method alters the initial microstructure of typical Grade 91 steel base metal before welding, while the second provides baseline microstructure characteristics and creep performance of a new alloy that is strengthened by the intermetallic Fe2Nb Laves phase. The initial microstructure of the Grade 91 steel can be controlled by Thermo-Mechanical Treatments, which aids in precipitation of fine (5-10 nm) MX particles in austenite before transformation to …

Slm Processing-Microstructure-Mechanical Property Correlation In An Aluminum Alloy Produced By Additive Manufacturing, Bryce Abstetar

Graduate Theses & Non-Theses

Additive manufacturing has become a highly researched topic in recent years all over the world. The current research evaluates the merits of additive manufacturing based on the mechanical, microstructural, and fracture properties of additive manufactured AlSi10Mg test specimens. The additive manufactured build plates consisted of tensile and fatigue test specimens. They were printed in the 0°, 30°, 60°, and 90° orientations relative to the build platform. Tensile and dynamic fatigue tests were conducted followed by microstructural characterization and fracture analysis. A wrought 6061 T6 aluminum alloy was also tested for comparison. Tensile tests revealed similar ultimate tensile strengths for all …

Fundamental Understanding Of Bond Formation During Solid State Welding Of Dissimilar Metals, Niyanth S

Doctoral Dissertations

Dissimilar metal welds are used in a wide range of applications to effect light weighting and for corrosion resistance. While fusion welding techniques are limited in their ability to fabricate dissimilar metal welds, solid state welding techniques are limited in their ability to fabricate complex geometries with dissimilar metal combinations. Hence alternative techniques need to be explored to fabricate complex geometries with dissimilar metals welds in the solid state. Ultrasonic additive manufacturing in a solid state additive manufacturing process that combines ultrasonic welding with mechanized tape layering to fabricate dissimilar metal welds in the solid state. Though extensive feasibility studies …

Photoluminescence Measurement On Low-Temperature Metal Modulation Epitaxy Grown Gan, Yang Wu

Graduate Theses and Dissertations

A low-temperature photoluminescence (PL) study was conducted on low-temperature metal modulation epitaxy (MME) grown GaN. By comparing the PL signal from high temperature grown GaN buffer layers, and MME grown cap layers on top of the buffer layers, it was found that MME grown GaN cap has a significantly greater defect-related emission. The band edge PL from MME grown GaN found to be 3.51eV at low temperature. The binding energy of the exciton in GaN is determined to be 21meV through temperature dependence analysis. A PL peak at 3.29eV was found in the luminescence of the MME grown cap layer, …

Thermoelectric Half-Heuslers: Synthesis, Processing, And Performance, Joseph Robert Croteau

Boise State University Theses and Dissertations

Thermoelectric half-Heusler compounds have potential to convert the heat wasted from industrial and transportation processes to useful electricity. Among the highest performing half-Heusler compounds are nano-structured bulk materials which have been arc-melted, pulverized into a nano-powder, and sintered by DC-hot press. High performing n- and p-type half-Heusler compounds with nominal composition of Hf_0.25Zr_0.75NiSn_0.99Sb_0.01 and Nb_0.75Ti_0.25FeSb, respectively, have been provided to us in both dense and powder form by our collaborators at the University of Houston. We consolidate these powders by SPS, refine these powders to improve both particle size …

Evaluation Of The Potential For Weld-Related Cracking In Cast 20cr-32ni-1nb Heat-Resistant Stainless Steel, John William Bohling

Masters Theses

Steam reforming of hydrocarbons is an important process for the production of hydrogen for industrial needs, such as ammonia synthesis. Due to the high temperature conditions (700 °C–900 °C), reformer furnace components require materials with excellent creep properties and thus highly alloyed austenitic stainless steels are typically employed. For reformer outlet manifolds, a cast, heat-resistant stainless steel with the composition 20Cr-32Ni-1Nb (ASTM A351 Grade CT15C) is widely used. However, after service exposure this alloy exhibits problems with liquation cracking in the base metal heat-affected zone (HAZ) during repair welding. In the work presented herein, two heats of material from centrifugally-cast …

Effect Of Hydrogen Pick-Up And Release Behavior On The Tensile Properties Of Electroplated 4340m High-Strength Steel, Blake Daylor, Joshua Fisher, Alan Michelen Ruiz

Materials Engineering

Hydrogen embrittlement of high-strength steel (4340M) was quantified through tensile testing and fractography (SEM). Three types of samples were obtained: rotating beam fatigue specimens, round (notched) tensile specimens, and flat panel specimens. In addition, three different plating types were analyzed (Ni, Cr, Cd-Ti) with a set of samples that was shot peened and a set that was not. Since some of the samples went through a hydrogen relief bake, another factor in our experiment was the amount of time it took for the samples to reach the baking process after they were electroplated (bake delay). There were three levels of …

Comparison Study Of Tensile Strength , Ductility, And Fracture Mode Of H11, Arp 2000, And Mp35n Connecting Rod Bolts For Use In High Performance Racing Engines, Megan Mccabe, Samuel Randall

Materials Engineering

Oliver Racing Parts (ORP) has historically purchased connecting rod bolts made of high strength, high cost, nickel-cobalt alloy, MP35N, and a medium strength, low cost, proprietary tool steel called ARP 2000. ORP has recently acquired capabilities to manufacture their own bolts. To determine the quality of their product as it compares to their previous supplier, ORP produced three different types of ⅜” diameter bolts: one set of bolts made of MP35N, and two sets of H11 bolts, designated H11A and H11B for their respective processing. The H11, ARP 2000, and MP35N bolts were tensile tested using a custom designed test …

Welding Procedure Qualification Of A36 Steel Plates Using The Gtaw And Gmaw Processes, Brecken Deoilers, Neri Lupian, Regan Rumph

Materials Engineering

The purpose of this project was to qualify welding procedure specifications for the Las Positas College welding program using A36 steel in accordance with American Welding Society (AWS) D1.1, B4.0, and B2.1. Qualification was to be performed using both 1G (flat) and 3G (vertical) positions for Gas Tungsten Arc Welding (GTAW) and Gas Metal Arc Welding (GMAW) processes. Required qualification procedures included two face and two root bend tests coupled with a visual inspection for cracks within the weld region greater than ⅛” long, along with two reduced section tensile tests to ensure the tensile strength exceeded 58 ksi if …

Effect Of Thermal Exposure On Tensile Strength And Microhardness Of Welded And Precipitation Hardened Rx82 Aluminum Alloy Extrusions In The T4 And T6 Conditions, Lucien Miller

Materials Engineering

This investigation is focused on the effect paint-bake cycles have on the tensile strength and microhardness of GMAW welded RX82 aluminum extrusions in T4 and T6 base conditions. To simulate the paint-bake cycle, T4 and T6 RX82 aluminum samples were GMAW welded and heat treated at 350°F, 390°F, and 425°F for durations of 30 minutes, 1.0 hour, and 2.0 hours, with five replicates for each treatment. Microhardness profiles of T4 samples treated at 350°F for 30 minutes and 1.0 hour display weld/HAZ HV values of 86.04 and 82.51 respectively, followed by maximums of 123.21 and 121.10. Average ultimate tensile strength …

Investigation Of Outlife Time On The Environmental Durability Of P2-Etched, Adhesively-Bonded Aluminum Alloys Using The Astm Wedge Test, Daniel Gross, Corey Sutton

Materials Engineering

P2 etchant is an environmentally-friendly aluminum etchant which has the potential to replace the Forest Products Laboratory (FPL) etchant as the industry standard. Environmental durability of adhesively-bonded aluminum surfaces etched using a paste version of the P2 etchant were tested using the Boeing-developed wedge test (ASTM D3762 - 03(2010)). This project specifically aimed to examine the relationship between outlife time (the time between etching and adhering) and the ability of bonded aluminum samples to pass the wedge test. Two aluminum alloys, 2024-T3 and 7075-T6, were wedge tested and the etched surfaces examined with an atomic force microscope (AFM) and a …

Controlling Grain Size In Cold Worked And Annealed 1100 Aluminum To Optimize Ductility In Rocket Diaphragm Systems, Ryan Lewis, Bryce Simmons, Jessica Williams

Materials Engineering

Liquid propellant rocket diaphragms require extreme ductility. 1100 Aluminum is used for its high ductility, but the post-processing cold work and subsequent anneal result in excessively large grains. The effect of heat treatment and cold work on grain size in 1100 aluminum was explored. The samples were cold worked to 0, 5, 10, 15 and 30% using tensile elongation. The samples were then heat treated per AMS 2770 with either a "Steel Conduction" (1000 – 1150°F/min) or a "Production" (16 – 18°F/min) heating rate. The grain size of the samples were measured using the mean lineal intercept method. The grain …

Grain Orientation Effects On The Rotating-Bending Fatigue Properties Of Forged 7050-T7452 Aluminum Alloy, Matt Cristler, Jonas Zhang

Materials Engineering

In order to investigate the effects of grain orientation on the high cycle fatigue properties of 7050-T7452 aerospace grade aluminum, rotating-bending fatigue tests were performed on longitudinal (LG) and short transverse (ST) specimens taken from two sample sets (Method A and Method B) of open die forged 7050 aluminum. The fatigue specimens were machined to a 0.2" gage diameter and 4" length and subsequently hand polished to a mirror finish to minimize potential crack initiation sites. The tests were conducted on a Fatigue Dynamics RBF-300 HT tester in the fully reversed loading condition, with stress levels varying from 20 ksi …

Superalloy Metallurgy A Gleeble Study Of Environmental Fracture In Inconel 601, Alan C. Demmons

Master's Theses

At temperatures above 0.5 Tm and in aggressive atmospheres predicting alloy performance is particularly challenging. Nickel alloys used in regimes where microstructure and properties are altered dynamically present unique requirements. Exposure may alter properties with unexpected early failure. The Gleeble is a valuable tool for investigation and simulation of thermo-mechanical properties of an alloy in various regimes up to the threshold of melting. In this study, four regimes of temperature and strain rate were simulated in an argon atmosphere to both investigate and document normal and abnormal failure modes. Commercial Inconel 601 was tested in selected regimes and in two …

Metals Additive Manufacturing Powder Aging Characterization, Thomas Russell Lovejoy, Nicholas Karl Muetterties, David Takeo Otsu

Mechanical Engineering

The metallic additive manufacturing process known as selective laser melting requires highly spherical, normally distributed powder with diameters in the range of 10 to 50 microns. Previous observations have shown a degradation in powder quality over time, resulting in unwanted characteristics in the final printed parts. 21-6-9 stainless steel powder was used to fabricate test parts, with leftover powder recycled back into the machine. Powder samples and test specimens were characterized to observe changes across build cycles. Few changes were observed in the physical and mechanical properties of the specimens, however, there were indications of chemical changes across cycles. Potential …

Microstructure And Creep Deformation Behavior Of A Hierarchical-Precipitate-Strengthened Ferritic Alloy With Extreme Creep Resistance, Gian Song

Doctoral Dissertations

Hierarchical NiAl [nickel-aluminium compound]/Ni₂TiAl [nickel-titanium-aluminum compound] or single Ni₂TiAl-precipitate-strengthened ferritic alloys have been developed by adding 2 or 4 weight percent [wt. %] of Ti [titanium] into a previously-studied NiAl-precipitate-strengthened ferritic alloy. A systematic investigation has been conducted to study the interrelationships among the composition, microstructure, and mechanical behavior, and provide insight into deformation micro-mechanisms at elevated temperatures.

The microstructural attributes of hierarchical or single precipitates are investigated in the Ti-containing ferritic alloys. Transmission-electron microscopy in conjunction with the atom-probe tomography is employed to characterize the detailed precipitate structure. It is observed that the 2-wt.-%-Ti alloy …

Temperature-Dependent Structures And Atomic Mixing Behaviors In High-Entropy Alloys, Louis J. Santodonato

Doctoral Dissertations

The goal of the present dissertation is to advance the fundamental understanding of the atomic mixing behavior in a new class of alloys, known as high-entropy alloys (HEAs), and provide new methods to develop HEAs for practical applications. The HEA design strategy is based upon the influence of configurational entropy of mixing, which serves as a driving force for the formation of disordered solid-solution structures in certain alloys. In particular, alloys containing multiple elements have a tendency to form stable, disordered structures, sometimes with exceptional engineering properties. Despite the tendency toward structural disorder, HEAs usually have some degree of structural …

Manipulation Of Surface Plasmon Resonance In Metal And Alloy Thin Films Using Dielectric Media, Benjamin Dubray Hall

Graduate Theses - Physics and Optical Engineering

Surface plasmon polaritons are coherent electron oscillations that propagate along an interface between a Drude metal and a dielectric medium. The excitation of polaritons is highly dependent on the dielectric properties of the metal, the thickness of the metal, and the optical properties of the dielectric material. First, plasmonic activity is assessed for several thicknesses of silver and nickel chromium under He-Ne incidence. Relationships between film thickness and metal dielectric function are explored in both cases. To manipulate the plasmonic activity at the silver surfaces, two methods are explored. Silver oxide was grown on the surface of the silver films, …

Magnetron Sputtering And Corrosion Of Ti-Al-C And Cr-Al-C Coatings For Zr-Alloy Nuclear Fuel Cladding, Devin Alan Roberts

Masters Theses

The disaster at the Fukushima Daiichi Nuclear Power Plant in March 2011 bought renewed focus to the issue of corrosion in nuclear fuel cladding applications. This thesis reports on the background behind these issues, the investigation strategy, and the analysis of experiments focused on mitigating oxidation of Zr-alloy fuel cladding. This thesis seeks to develop magnetron sputtered Ti-Al-C and Cr-Al-C coatings for Zr-alloy substrates and characterize the as-deposited and corroded samples.

Ti-Al-C and Cr-Al-C coatings were deposited onto ZIRLO, Si, and Al₂O₃ [Aluminum Oxide] substrates under various sputtering conditions. A combinatorial sputtering method was employed to refine …

Cyclic Behavior Of A Hybrid Light Gauge And Hss Mezzanine Structural System, Michael John Kren

Master's Theses (2009 -)

Cold-formed steel is emerging as an alternative material in the building industry to hot-rolled steel for smaller buildings and indoor structures also called mezzanines. Cyclic testing of a full-scale mezzanine structures composed of cold-formed structural channel beams connected to hollow structural steel (HSS) columns cap plates using wedge expansion anchors at the base plate to generate rotation restraint, is performed in this research. The characteristics of the structure will be explained by displaying full experimental results of structural testing. Unfortunately, limited experimental data outlining the behavior of these structures is available and design criteria is very limited. Thus, there is …

Chlorination And Selective Vaporization Of Rare Earth Elements, Daniel Gaede

Graduate Theses & Non-Theses

No abstract provided.

Electrochemical Characterization Of Xanthate Chemisorption On Copper And Enargite, Tyler Broden

Graduate Theses & Non-Theses

The electrochemical reactions of copper and enargite (Cu₃AsS₄) were studied in the absence and presence of xanthate by cyclic voltammetry (C.V.) using electrodes fashioned from pure copper wire obtained from the Metallurgical and Materials Engineering Department, and an enargite mineral sample obtained from the Orphan Girl mine in Butte, MT. Voltammograms were produced in buffer solutions of pH values ranging from 7-12. Electrochemical reactions were discerned by comparing E_H-pH diagrams calculated from thermodynamics using StabCal, a computer program developed by Dr. Huang at Montana Tech. The chemisorption of xanthate on the surface of copper …

Vacuum Brazing Of Diamond To Tungsten Carbide, Zhiyong Yin

Graduate Theses & Non-Theses

Diamond tools are increasingly gaining importance as cutting and drilling materials for a wide variety of industrial applications. Polycrystalline diamond (PCD) is the main ultrahard material commercially used in the oil and gas drilling industry. In this study, a reactive brazing process was developed to join polycrystalline diamond (PCD) to WC-13 wt% Co, to form the cutter for fixed-cutter drill bit applications.

Most nonmetals including polycrystalline diamond are not wet by and cannot easily be joined with conventional brazing alloys due to their chemical stability. The experimental approach was first to analyze the effect of adding an active metal (Ti, …

Cryogenic Processing Of Al 7050-T7451 Alloy For Improved Surface Integrity, Bo Huang

Theses and Dissertations--Mechanical Engineering

Al 7050-T7451 alloy with good combinations of strength, stress corrosion cracking resistance and toughness, is used broadly in the aerospace/aviation industry for fatigue-critical airframe structural components. However, it is also considered as a highly anisotropic alloy as the crack growth behavior along the short transverse direction is very different from the one in the long transverse direction, due to the inhomogeneous microstructure with the elongated grains distributed in the work material used in the sheet/plate applications. Further processes on these materials are needed to improve its mechanical and material properties and broaden its applications.

The material with ultra-fine or nano …

Conversion Casting: Adapter Hub, Joseph M. Coup

All Undergraduate Projects

The concept of conversion casting makes manufacturing major components much more efficient with regards to time and cost. The conversion cast of the adapter hub used in the Victair Mistifier is a major component that requires 8 hours to machine. The existing hub starts from steel stock and then that block of steel is placed into a CNC machine and coded in to create the adapter hub. The manufacturing method changes to a casting for the adapter hub will create a replicated part that requires 1.5 hours of post machining. The intricate design makes a conversion to casting more effective …

Thermomechanical Processing Of Aluminum Micro-Alloyed With Sc, Zr, Ti, B, And C, Cameron Mcnamara

Dissertations, Master's Theses and Master's Reports

Critical exploration of the minimalistic high strength low alloy aluminum (HSLA-Al) paradigm is necessary for the continued development of advanced aluminum alloys. In this study, scandium (Sc) and zirconium (Zr) are examined as the main precipitation strengthening additions, while magnesium (Mg) is added to probe the synergistic effects of solution and precipitation hardening, as well as the grain refinement during solidification afforded by a moderate growth restriction factor. Further, pathways of recrystallization are explored in several potential HSLA-Al systems sans Sc. Aluminum-titanium-boron (Al-Ti-B) and aluminum-titanium-carbon (Al-Ti-C) grain refining master alloys are added to a series of Al-Zr alloys to examine …

Investigation And Modeling Of Al3(Sc, Zr) Precipitation Strengthening In The Presence Of Enhanced Supersaturation And Within Al-Cu Binary Alloys, Kyle Deane

Dissertations, Master's Theses and Master's Reports

Diffuse Al-Sc and Al-Zr alloys have been demonstrated in literature to be relatively coarsening resistant at higher temperatures when compared with commonly used precipitation strengthening alloys (e.g. 2000 series, 6000 series). However, because of a limited strengthening due to the low solubility of scandium and zirconium in aluminum, and owing to the scarcity and therefore sizeable price tag attached to scandium, little research has been done in the way of optimizing these alloys for commercial applications.

With this in mind, this dissertation describes research which aims to tackle several important areas of Al-Sc-Zr research that have been yet unresolved. In …

Nd2fe14b: (Nd1-X Dyx)2 Fe14b Core-Shell Structure Formation By Hot Press Liquid Phase Sintering, Li Chen

Dissertations, Master's Theses and Master's Reports

The purpose of this project is to produce Nd rich core-Dy rich shell grain structure in liquid phase sintered alloys by consolidating Dy rich powder mixed with powder. The technical barrier to producing the core-shell microstructure is that the Dy composition variations will homogenize during the consolidation process. This dissertation is based on the hypothesis that compositional homogenization of the core-shell structure can be minimized if consolidation occurs under applied pressure (hot press liquid phase sintering). The hypothesis is tested by comparing the homogenization of the Dy composition to the degree of consolidation with and without applied pressure. It is …

The Effect Of Solidification Rate And Solutionizing Quench Rate On The Mechanical Properties And Hardening Response Of Aluminum Alloys: A Quantitative Comparison, Rafael Gil-Figueroa

Dissertations, Master's Theses and Master's Reports

A comparative study of five aluminum alloys was performed to characterize the effect of solidification rate and quench rate on casting microstructure and properties. The alloys were cast in the geometry for Jominy End Quench (JEQ) testing, so as to take advantage of the JEQ test’s ability to give data on multiple quench rates in a single sample and illustrate the quench sensitivity of an alloy. While the Jominy End Quench test has been used in aluminum alloys, the effects of solidification rates have not been assessed in depth. The work done by other studies has either focused on a …

Investigation Of The Resistance To Demagnetization In Bulk Rare-Earth Magnets Comprised Of Crystallographically-Aligned, Single-Domain Crystallites With Modified Intergranular Phase, Jie Li

Dissertations, Master's Theses and Master's Reports

The research presented in this dissertation investigates whether an increased coercivity of Neodymium-Iron-Boron (Nd2Fe14B) based bulk magnets at elevated temperature (160°C), which is now only obtainable by substituting ~7wt% dysprosium (Dy) for a portion of neodymium (Nd), can be achieved through specific microstructural modifications with decreased Dy concentrations. The approach is to reduce the size of individual crystallographically-aligned grains in the magnet so that each grain can only support a single magnetic domain and to simultaneously dilute the Nd-Fe inter-granular phase present in conventional magnets with a non-Fe-containing, Nd-rich phase (Nd-Cu alloy) in an attempt to partially magnetically isolate the …