Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 22 for “"Ductile-to-brittle"”.
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The Ductile to Brittle Transition in Polycarbonate
… that is stress state and rate-dependent in order to simulate the ductile to brittle failure transition in polycarbonate. The cohesive zone model is motivated by experimental evidence that two different critical energies per unit area of crack growth exist in glassy polymers. A higher energy state …
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Effects of prior ductile tearing on cleavage fracture in the ductile-to-brittle transition region
… effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values ($J\sb{c}$) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but …
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Effects of microstructure and strain ageing on toughness of nuclear PWR reactor weld metals
… of microstructure and prestraining and ageing on ductile-to-brittle transition temperature, fracture toughness and cleavage fracture resistance of a multi-pass low-alloy ferritic steel weld metal have been investigated. The weld metal simulated submerged arc welds used in the fabrication of …
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Impact fracture of embrittled stainless steels
Hydrogen embrittlement of austenitic stainless steels and temper embrittlement of a martensitic stainless steel have been studied by impact testing, metallography, and SEM fractography. New data for uncharged and hydrogen-charged specimens of Types 304L and 316L austenitic stainless steels show …
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Evaluation of Temper Embrittlement in 2.25 Cr- 1 Mo Weld Metals Utilizing X-Ray Diffraction.
Temper embrittlement in low alloy steel is a phenomenon of reversible embrittlement occurring when a susceptible alloy is held in or slowly cooled through a temperature range of 1100 - 650 °F (13). Characteristics of this type of embrittlement are a reduction in notch toughness, an increase in the …
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The effects of hydrogen on the deformation and fracture behavior of the metastable beta-titanium alloy, TIMETAL(RTM) 21S
… TIMETAL$\sp\circler$ 21S, exhibits a sharp ductile-to-brittle transition when the hydrogen concentration is increased slightly above H/M $=$ 0.22. To understand this sharp transition, a series of experiments was devised to test for the possible hydrogen embrittlement mechanisms. In situ …
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Effect of heat treatment and mechanical deformation on the structure and properties of iron-manganese alloys (10-40% Mn).
… under investigation have been reported as being brittle by some authors while others find them to be as ductile as steels of the same tensile strength and suggested that the brittleness was due to high carbon and phosphorus contents. With this possibility in mind, the impurity content of the …
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Fracture Behavior Characterization of Conventional and High Performance Steel for Bridge Applications
… Project 5-238, Design and Fabrication Standards to Eliminate Fracture Critical Concerns in Steel Members Traditionally Classified as Fracture Critical, researchers aim to take advantage of advances made in both steel production technology and in the field of fracture mechanics. Testing and …
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Roles of grain boundaries in cleavage cracking and thermal crack arrest experiments in iron-silicon alloy
… in steel offer an important resistance to the propagation of cleavage cracks that affects the fracture toughness and can modulate the ductile-to-brittle transition temperature of fracture downward. This behavior has been studied in this thesis in detail. In grain-boundary toughness …
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Structural evolution of the Max Meadows thrust sheet, Southwest Virginia
… developed in progressive simple shear near the ductile-to-brittle transition. Heterogeneous simple shear (γ < 3) was localized in incompetent, anisotropic pelitic rocks (Rome Formation) along the base of a composite, 5-11 km. thick thrust sheet. Folds, which vary from upright and open to …
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Tectonic evolution of the Western Limassol Forest Complex, Cyprus
… studies have revealed magmatic and structural histories that differ markedly from the Penrose-type ophiolite of the Troodos Massif to the north. In the WLFC, a tectonised harzburgite of upper mantle origin has been intruded by multiple ultramafic and gabbroic plutons and swarms of mainly NE-SW …
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Design and construction of a motor-actuated sea ice compression testing machine
… a compression machine capable of exerting up to 50 kN of force and accommodating strain rates critical for studying sea ice compressive strength. Field tests were conducted using ice cores collected from the MIZ consolidated ice. Compression tests were performed at strain rates around 4 x …
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Relationship of moulding pressure and weigh of granulate in improving the mechanical and characteristics of biopolymer from renewable resources
… oil are limited. Pouring waste cooking oil down to the drain or sewers leads to clog and odour as well as damage wastewater leading to problems for humanlife. Thus, in this research, vegetable waste cooking oil is used as raw material to produce foam. This foam was crosslink with flexible …
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Mechanical properties of materials for fusion power plants
… a hot plasma of deuterium and tritium, reacting to produce particles and 14 MeV neutrons, which are collected by a cooling system. Their kinetic energy is transformed into heat and electricity via steam turbines. The constant ux of neutrons on the rst wall of the reactor produces atomic …
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Phase transformations in welded supermartensitic stainless steels
… been introduced in the oil and gas industries to substitute more expensive duplex stainless steels for onshore and offshore tubing applications. Although easily joined by arc welding processes, the service life of the supermartensitic welded joint in corrosive environments relies to a large …
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Morphology and Mechanical Properties of High Density Polyethylene Exposed to Chlorinated Water
… (as-extruded and heat treated) are exposed to 5ppm chlorinated water at 70 degrees Celsius for up to 1250 hours. Changes in semicrystalline polymer morphology as a function of exposure time are evaluated and compared with tensile and creep test data. Additionally, data are evaluated as a …
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Hydrogen embrittlement resistance in advanced high strength: vanadium bearing and TRIP-assisted steels
… transitions associated with damage, these lead to failure especially when hydrogen enters the lattice and gets trapped in defects. It is desired to design advanced steels highly resistant to hydrogen embrittlement (HE), while preserving a balance between their superior strength and ductility. …
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Effects of Powder Reuse on The Mechanical Properties of Electron Beam Additively Manufactured Ti-6Al-4V
… incredible promise for small batch, highly customizable part production. Powder bed fusion systems build parts layer by layer from metal powder that is manufactured according to stringent requirements, including chemistry, sphericity and particle size distribution. To maximize process economy, …
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Degradation studies on recycled Polyethylene terephthalate
This project aims to investigate the influence of UV on the properties under natural and artificial weathering. The real-time outdoor weathering exposures provide the most accurate results but, they are very slow and manufacturers cannot afford to wait in order to see if a new or improved product …
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Polylactic Acid-Based Polymer Blends for Durable Applications
… climate change increase, this field is likely to grow even larger. One bioplastic that has received a great deal of attention is polylactic acid (PLA). In the past, this material was used mainly in medical or specialty applications, but advancements in manufacturing have led to a desire to use …
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