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Full-Text Articles in Engineering
Characterization And Modeling Of The Martensite Transformation In Advanced High-Strength Steels, Stephen Roy Cluff
Characterization And Modeling Of The Martensite Transformation In Advanced High-Strength Steels, Stephen Roy Cluff
Theses and Dissertations
Multiple studies on the microstructures of advanced high-strength steels are presented here that seek to add to the already substantial body of knowledge on martensite in steel. These studies seek to gain additional insight into the role that the martensite transformation has on the observed mechanical properties of modern steels. Crystallographic Reconstruction of Parent Austenite Twin Boundaries in a Lath Martensitic Steel The study of post-transformation microstructures and their properties can be greatly enhanced by studying their dependence on the grain boundary content of parent microstructures. Recent work has extended the crystallographic reconstruction of parent austenite in steels to include …
Manipulation And Automation Of Fbj Short-Axis Fasteners, Shane Forrest Wood
Manipulation And Automation Of Fbj Short-Axis Fasteners, Shane Forrest Wood
Theses and Dissertations
Legislative and market pressures are pushing automakers to achieve new fuel economy requirements in the coming years. To help achieve these goals automakers are reducing the overall weight of the vehicle by increasing the use of high-strength aluminum and advanced high-strength steels, and with this increased use comes the desire to quickly, and securely, join these materials within the vehicle. Friction bit joining is a process that lends itself well to joining these materials. This process uses consumable fasteners that need to be used in an automated production line. The geometry of these fasteners causes two main problems: the bits …
Microstructural Evaluation Of Hydrogen Embrittlement And Successive Recovery In Advanced High Strength Steel, Quentin Scott Allen
Microstructural Evaluation Of Hydrogen Embrittlement And Successive Recovery In Advanced High Strength Steel, Quentin Scott Allen
Theses and Dissertations
Advanced high strength steels (AHSS) have high susceptibility to hydrogen embrittlement, and are often exposed to hydrogen environments in processing. In order to study the embrittlement and recovery of steel, tensile tests were conducted on two different types of AHSS over time after hydrogen charging. Concentration measurements and hydrogen microprinting were carried out at the same time steps to visualize the hydrogen behavior during recovery. The diffusible hydrogen concentration was found to decay exponentially, and equations were found for the two types of steel. Hydrogen concentration decay rates were calculated to be -0.355 /hr in TBF steel, and -0.225 /hr …
A Simple Method For Evaluating Wear In Different Grades Of Tooling Applied To Friction Stir Spot Welding, Kirtis Frankland Kennard
A Simple Method For Evaluating Wear In Different Grades Of Tooling Applied To Friction Stir Spot Welding, Kirtis Frankland Kennard
Theses and Dissertations
In this study tools consisting of a 5mm cylindrical pin and a 12mm shoulder held by a simple tool holder were used to compare the wear of 11 tooling materials. The objective was to determine if using these tools in a spot welding configuration to simulate friction stir welding could differentiate the potential performance of tooling materials. All tools were made of varying percentages of polycrystalline cubic boron nitride (PCBN), tungsten (W) and rhenium (Re). The materials are referred to herein as GV1, GV2, G1, G2, G3, G4, G5, G6, G7, G8 and G9.
The tools were run to 205 …
Study On The Fracture Toughness Of Friction Stir Welded Api X80, Allan M. Tribe
Study On The Fracture Toughness Of Friction Stir Welded Api X80, Allan M. Tribe
Theses and Dissertations
High strength low alloy (HSLA) steels have been developed to simultaneously have high yield strength and high fracture toughness. However, in practical applications steel must be welded. Traditional arc welding has proven detrimental to the fracture toughness of HSLA steels. Friction stir welding has recently shown mixed results in welding HSLA steels. The range of welding parameters used in these recent studies however has been very limited. With only a few welding parameters tested, the effect of spindle speed, travel speed, and heat input on the fracture toughness of friction stir welded HSLA steel remains unknown. To understand how the …
Buckling And Crippling Of Square Steel Thin-Walled Tubes Fabricated With Symmetrically-Overlapping U-Channels And Foam, David Camenish Gelder
Buckling And Crippling Of Square Steel Thin-Walled Tubes Fabricated With Symmetrically-Overlapping U-Channels And Foam, David Camenish Gelder
Theses and Dissertations
Testing and analysis has been performed on square steel thin-walled tubes fabricated using symmetrically-overlapping U-channels and foam. This research analyzes flange-to-flange attachment, effect of foam in the columns, effect of adhesive stiffness, and influence of steel thickness, as related to the local buckling loads, global buckling loads, and crippling loads. Four 14-foot (4.27 m) foam-filled, thin-walled, galvanized steel columns were manufactured by Novatek, Inc. and tested in axial compression with pinned boundary conditions. For three of the four configurations, the two-piece 4-in. (10.2-cm) square shell surrounded prefabricated polystyrene foam inserts; the fourth column had no foam insert. The column outer …
Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher
Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher
Theses and Dissertations
The development and example applications of a new EBSD-based texture analysis system are presented. This new system uses the cross-correlation function to compare two EBSD patterns at a number of corresponding regions in each pattern to calculate the deformation gradient tensor. Bragg's Law-based simulated EBSD patterns are used as reference patterns in the cross-correlation method to enable the measurements of absolute elastic strain and lattice orientation at discrete points in a crystalline sample. The resolution limits of this new method are explored using a variety of computational and physical experiments. The simulated pattern method is estimated to be able to …