Browsing by Subject "Titanium"

Now showing 1 - 5 of 5

Carbonatites
(2009-07) Barker, Daniel S.
Controlling microstructure in nickel 200, titanium grade 2, and titanium grade 5 for the calibration of ultrasonic microstructure characterization
(2018-05) Schick, Matthew Brian; Taleff, Eric M.
Ultrasonic testing is a promising technique by which to nondestructively determine the subsurface material microstructure characteristics of metallic components. Development of this technique requires reference specimens of known microstructure by which to calibrate the ultrasonic signal response. Such reference specimens were produced in Nickel 200 (commercial-purity Ni or Ni 200), Titanium Grade 2 (commercial-purity Ti or TiGr2) and Titanium Grade 5 (Ti-6Al-4V or TiGr5) materials in the laboratory. The microstructures produced and methods of their production are presented and discussed. Particular attention is given to techniques appropriate in the general research laboratory environment. Recrystallized grain size is controlled across a wide range in the Ni 200, TiGr2, and TiGr5 materials by annealing after cold rolling. Heat treatments and hot compression further produced fully lamellar, duplex, and equiaxed (globular) microstructure forms in the TiGr5 material. The theory of ultrasonic signals interacting with grain boundaries and grain/phase interfaces will be discussed in light of the microstructures produced within these specimens
A fracture mechanics approach to accelerated life testing for cathodic delamination at polymer/metal interfaces
(2013-05) Mauchien, Thomas Kevin; Liechti, K. M.
This work presents a fracture mechanics analysis of the cathodic delamination problem for the polyurethane/titanium and polyurea/steel interfaces. The nonlinear behavior of both polymers was investigated. The recent Marlow model was used to define the strain energy function of the polymers. Viscoelastic effects of the polyurea were also studied. The Marlow model was associated with a nine-term Prony series. This model was seen to represent experimental data relatively well for a wide range of strain rates both in tension and compression. The driving force for delamination, the strain energy release rate G, is presented for both interfaces. Cathodic delamination data for several temperatures are presented as crack growth rate as a function of crack driving force. The approach recognizes that both temperature and stress can be used as accelerated life testing parameters.
Improved accelerated life testing for cathodic delamination
(2012-03) Liechti, K. M.
The overall objective of this work is to establish the feasibility of modeling the cathodic delamination problem in polymer coated submarine components with a view to developing a more accurate testing standard for Accelerated Life Testing (ALT) and to determining the effectiveness of new approaches for combating cathodic delamination in a quantitative manner ... An approach has ... been taken to characterize cathodically delaminating rubber/metal interfaces and forms the basis for the current attempt to model cathodic delamination between polyurethane and titanium. Once this model is established it will allow for an accelerated life protocol to be developed where stress and temperature will be used to accelerate crack growth in laboratory specimens while retaining the same crack growth mechanisms that are seen in service. The elements of the approach are threefold: 1. Determining the mechanical behavior of the polyurethane and titanium. The former is more challenging due to its nonlinearly elastic behavior. 2. Conducting a stress analysis of the specimen to be used in the cathodic delamination experiment in order to design it to provide the anticipated range of energy release rate values. 3. Conducting the cathodic delamination experiments and determining the crack velocity profiles for the polyurethane/titanium interface as a function of energy release rate and temperature.
Mechanical Properties of Pure Titanium Models Processed by Selective Laser Melting
(2002) Santos, Edson; Abe, F.; Kitamura, Y.; Osakada, K.; Shiomi, M.
The influence of laser processing parameters on mechanical properties and microstructure of pure titanium models made by selective laser melting is investigated. The density of the models can reach higher than 95% under proper conditions. Although the tensile strength test shows results comparable to the wrought material, the impact and torsional fatigue strengths are low because of porosity and oxygen pick-up suggested by increasing of hardness. Hot isostatic pressing allows almost full densification and greatly improves mechanical properties.