Download or read book Integrating Temperature Dependence Into a Microstructure sensitive Fatigue Model for Titanium Alloys written by Jared Michael Darius and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work seeks to integrate temperature dependence into a microstructure-sensitive fatigue model for titanium alloys produced by both extrusion and electron beam melting (EBM) additive manufacturing, revising and enhancing the MultiStage Fatigue (MSF) model as the foundational model framework. Traditional fatigue modeling has required design engineers to conservatively use a lower-bound estimate of fatigue life predictions given a statistically significant spread of experimental data that can span up to two or sometimes three orders of magnitude for a given test condition. This variation in fatigue data has since been accounted for with the advent of the MSF model, linking individual microstructures to their influence on fatigue life in three distinct stages: incubation, small crack growth, and long crack growth. Since the inception of the MSF model in 2003 by McDowell et al. [1] where it was applied to a cast aluminum alloy, its application has been expanded to a wide range of aluminum alloys, magnesium alloys, steels, polymers, and even one titanium alloy made by laser engineered net shaping (LENS). The MSF model correlates a set of parameters to unify model constants for a given material chemistry across a range of alloys and processing methods. Currently, the Ti-6Al-4V (Ti64) alloy is being implemented in aircraft and spacecraft as a corrosion-resistant lightweight structural metal with good strength retention at elevated temperatures. However, the MSF model lacks any temperature dependence. Therefore, this work integrates a temperature dependence to the MSF model for the first time, applying the model to the Ti64 alloy in two new processing methods. First the microstructure of both materials is characterized. Next, monotonic and fatigue experiments are conducted with both extruded and EBM Ti64 at room temperature and at elevated temperatures (150, 300, and 500 °C). Subsequent fractographic analysis reveals the most deleterious microstructures and failure mecha

Download or read book Microstructure sensitive Plasticity and Fatigue of Three Titanium Alloy Microstructures written by Benjamin Daniel Smith and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium alloys are employed in many advanced engineering applications due to their exceptional properties, i.e., a high strength-to-weight ratio, corrosion resistance, and high temperature strength. The performance of titanium alloys is known to be strongly affected by its inherent microstructure, which forms as a result of its thermo-mechanical processing. These microstructures produce compromise relationships between beneficial and detrimental effects on the alloy's performance. To study these structure-property relationships, two distinct crystal plasticity algorithms have been calibrated to data acquired from cyclic deformation experiments performed on three different Ti microstructures: (1) Ti-6Al-4V beta-annealed, (2) Ti-18 solution-treated, age-hardened (STA), and (3) Ti-18 beta-annealed, slow-cooled, age-hardened (BASCA). The calibrated models have been utilized to simulate fatigue loading of variant microstructures to investigate the influence of mean grain size, crystallographic texture, and phase volume fraction. The driving force for fatigue crack nucleation and propagation is quantified through the calculation of relevant fatigue indicator parameters (FIPs) and radial correlation functions are employed to study the correlation between favorably oriented slip systems and the extreme value FIP locations. The computed results are utilized to observe fatigue performance trends associated with changes to key microstructural attributes.

Download or read book Fatigue Properties of High Strength Titanium Alloys at Elevated Temperatures IMI 685 written by and published by . This book was released on 1986 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Elucidating the Role of Microstructure Texture and Microtexture on the Dwell Fatigue Response of Ti 6Al 4V written by Alec Mitchell Blankenship and published by . This book was released on 2016 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ambient temperature dwell sensitivity is known to be deleterious to the fatigue response of near-alpha titanium alloys. Dwell fatigue refers to the presence of a sustained hold at peak stress as opposed to the continuous variation of normal cyclic fatigue loading. This reduction in failure life-times from dwell loading is attributed to early crack nucleation and faster crack propagation. The degradation is the result of plastic anisotropy on the microstructural scale along with tendency of titanium alloys to creep at low temperatures at stresses well below the 0.2% offset yield strength. Despite being the most widely used titanium alloy, Ti-6Al-4V has not been the subject of most dwell fatigue research. Generally, dwell sensitivity is microstructurally dependent and believed to only affect Ti-6Al-4V when severe crystallographic texture is present and under high peak stress loading. Recent studies, however, have suggested that small clusters of preferred crystal orientations, known as micro-textured regions (MTR), can have a significant effect on the dwell sensitivities in Ti-6Al-4V even without severe overall texture in the material.In this study, smooth-bar fatigue specimens were subjected to uniaxial fatigue at 20 Hz cyclic and 2-min dwell loading conditions under load-control at stresses representative of service conditions, until failure occurred. A reduction in specimen life-times by approximately a factor of three was observed under dwell conditions, which was less than for the highly susceptible near-a titanium alloys such as Ti-6Al-2Sn-4Zr-2Mo, where the dwell debit is often in excess of a factor of ten. Measurement of fatigue and dwell fatigue crack growth rates revealed a significant acceleration of the dwell crack growth rates in certain cases. Backscattered electron imaging and electron backscattered diffraction were utilized to quantify the interaction between the cracks and local microstructure. Though no correlation was found between crack growth rate and the local microstructure and crack trajectory, strong correlation was found between crack growth and the presence of grains with [0001] axes at small angles (

Download or read book Crystal Plasticity Finite Element Methods written by Franz Roters and published by John Wiley & Sons. This book was released on 2011-08-04 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by the leading experts in computational materials science, this handy reference concisely reviews the most important aspects of plasticity modeling: constitutive laws, phase transformations, texture methods, continuum approaches and damage mechanisms. As a result, it provides the knowledge needed to avoid failures in critical systems udner mechanical load. With its various application examples to micro- and macrostructure mechanics, this is an invaluable resource for mechanical engineers as well as for researchers wanting to improve on this method and extend its outreach.

Download or read book Fatigue of Beta Processed and Beta Heat treated Titanium Alloys written by Russell Wanhill and published by Springer Science & Business Media. This book was released on 2011-10-28 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication reviews most of the available literature on the fatigue properties of β annealed Ti-6Al-4V and titanium alloys with similar microstructures. The focus is on β processed and β heat-treated alloys because β annealed Ti-6Al-4V has been selected for highly loaded and fatigue-critical structures, including the main wing-carry-through bulkheads and vertical tail stubs, of advanced high-performance military aircraft. An important aspect of the review is a concise survey of fatigue life assessment methods and the required types of fatigue data. This survey provides the background to recommendations for further research, especially on the fatigue behaviour of β annealed Ti-6Al-4V under realistic fatigue load histories, including the essential topic of short/small fatigue crack growth. Such research is required for independent fatigue life assessments that conform to the aircraft manufacturer’s design requirements, and also for life reassessments that most probably will have to be made during the service life of the aircraft.

Download or read book Challenges in Mechanics of Time Dependent Materials Volume 2 written by Alex Arzoumanidis and published by Springer. This book was released on 2017-10-17 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: ​Challenges in Mechanics of Time-Dependent Materials, Volume 2 of the Proceedings of the 2017 SEM Annual Conference& Exposition on Experimental and Applied Mechanics, the second volume of nine from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental Mechanics, including papers in the following general technical research areas: Characterization Across Length ScalesExtreme Environments & Environmental EffectsViscoelasticityStructure Function PerformancePolymer ViscoplasticityMetallic MaterialsFracture/Fatigue/DamageCompositesSoft Materials

Download or read book Microstructure and Temperature Effects on the Fatigue Variability Behavior of AN Alpha beta Titanium Alloy and Implications for Life Prediction Postprint written by and published by . This book was released on 2006 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the effects of microstructure and temperature on the fatigue variability behavior of the alpha+beta titanium alloy, Ti-6Al2Zr-4Sn-6Mo (Ti-6-2-4-6). These variables had separate influence on the minimum, and the mean behavior. This was related to perhaps a fundamental aspect of fatigue variability which dictates that at any stress level, the mean is dominated by a mechanism different from the one controlling the lower-tail behavior. As a result in this material, while the mean response was increasingly dominated by the crack initiation regime with decreasing stress level (which is the conventionally expected behavior), at the same time the life-limiting behavior was controlled by the crack growth regime. This produced a very systematic effect of microstructure and temperature on total uncertainty in lifetime depending on the sensitivity of crack initiation and growth regimes to these variables. We suggest a new paradigm to treat the fatigue variability behavior and show that, this can have significant implications for life management especially, with respect to reducing the uncertainty with life prediction and improving the reliability of design life.

Download or read book Influence of Microstructure on Elevated Temperature Fatigue Resistance of a Titanium Alloy written by C. Hoffmann and published by . This book was released on 1982 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The strain-controlled, elevated-temperature, low-cycle fatigue behavior of a near ? titanium alloy, Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242S), has been studied in both air and vacuum (10-5 torr) at 525°C over a range of frequency and strain. Of particular interest in this investigation were the influence of microstructure and environment on fatigue behavior. Two different microstructures were obtained by combinations of mechanical processing and heat treatment above and below the ?-transus temperature. Particular attention was given to these microstructural variations and to the effect of environment on the high-temperature low-cycle fatigue behavior of this alloy. The nature of fatigue crack initiation sites was examined by a precision sectioning method. The microstructure was found to have a pronounced effect on fatigue life as well as on the fatigue crack initiation process. Tests performed in vacuum revealed no influence of frequency on fatigue life, which indicated that environmental factors were responsible for the observed frequency effect on tests performed in air. It was also observed that testing in vacuum led to the formation of a number of subsurface crack nucleation sites and to a longer fatigue life. Crack origins in specimens tested in air were located at the surface, and the initiation sites were larger than those observed in vacuum. The features of a fatigue resistant microstructure in addition to environmental effects at elevated temperature are identified and discussed.

Download or read book Microplasticity written by Charles J. McMahon and published by . This book was released on 1968 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Robust Design of Microelectronics Assemblies Against Mechanical Shock Temperature and Moisture written by E-H Wong and published by Woodhead Publishing. This book was released on 2015-05-23 with total page 477 pages. Available in PDF, EPUB and Kindle. Book excerpt: Robust Design of Microelectronics Assemblies Against Mechanical Shock, Temperature and Moisture discusses how the reliability of packaging components is a prime concern to electronics manufacturers. The text presents a thorough review of this important field of research, providing users with a practical guide that discusses theoretical aspects, experimental results, and modeling techniques. The authors use their extensive experience to produce detailed chapters covering temperature, moisture, and mechanical shock induced failure, adhesive interconnects, and viscoelasticity. Useful program files and macros are also included. - Discusses how the reliability of packaging components is a prime concern to electronics manufacturers - Presents a thorough review of this important field of research, providing users with a practical guide that discusses theoretical aspects, experimental results, and modeling techniques - Includes program files and macros for additional study

Download or read book Deformation mechanism Maps written by H. J. Frost and published by Pergamon. This book was released on 1982 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Titanium Alloys at Elevated Temperature written by Mike R. Winstone and published by CRC Press. This book was released on 2001 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the fourth in a series of international conferences on the Microstructure of High Temperature Materials and the first to exclusively focus on the microstructure and properties of titanium alloys. Papers demonstrating the exploitation of these alloys in a wide range of commercial high temperature applications from the automotive to the aerospace industries were presented.

Download or read book Fatigue of Beta Processed and Beta Heat Treated Titanium Alloys written by and published by Springer. This book was released on 2011-10-29 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling of Microstructure Evolution During the Thermomechanical Processing of Titanium Alloys Preprint written by and published by . This book was released on 2008 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Titanium and titanium alloys are widely used for a variety of aerospace, chemical, marine, and other specialty applications because of their high strength, low density, good ductility, fatigue and corrosion resistance, as well as other properties. Depending on the application, a specific property (or combination of properties) can be obtained through microstructural modification. Microstructure evolution and control in titanium alloys is heavily dependent on the allotropic transformation from a hexagonal-close-packed crystal structure (denoted as alpha phase) found at low temperatures to a body-centered-cubic crystal structure (denoted as beta phase) at high temperatures. For pure titanium, this occurs at 882 deg C. In many titanium alloys, the beta phase is partially stabilized at lower temperatures, and the equilibrium volume fractions of alpha and beta vary with temperature. The temperature at which a specific alloy becomes entirely beta is called the beta transus. The conditions used for hot working and heating/heat treatment are often selected relative to the beta-transus temperature.

Download or read book Improvement of Fatigue Properties in Titanium Alloys written by Charles M. Gilmore and published by . This book was released on 1974 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue crack initiation lives of annealed Ti-6Al-4V alloys were determined at low (+ or - 0.006 in/in) and high (+ or - 0.012 in/in) shear strain amplitudes. The initiation life was separated from the propagation life by determining when extensive axial elongation of the specimen occurred. At 0.006 and 0.012 strain amplitudes the a-b annealed (alpha beta A) and mill annealed (MA) specimens have similar lives to crack initiation followed by recrystallized anneal (RA) and beta annealed (beta A) specimens. Analysis of the beta A specimens showed that structure related fatigue fracture was occurring and this was not observed with the other anneals. 'Cyclic creep' tests were conducted on each anneal treatment and the RA material exhibited the best dimensional stability and the beta A material the worst. These results are in accordance with the expected phase stability of each alloy; the RA material should be the closest to an equilibrium microstructure; the Beta A material the farthest from an equilibrium microstructure. The greatest increase in fatigue lives occurred for specimens quenched from a solution temperature of 1650 F, which is about 100 F below the beta transus. Reduction of solution temperature to 1550 F, or increases to 1750 F and 1950 F resulted in lower lives than the 1650 F solution temperature. The fracture surface of the material quenched from 1950 F had brittle type fatigue striations, also the region of fast fracture had evidence of microstructure effects. (Author).

Download or read book Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6 2 2 2 2 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared with two more widely used titanium alloys (Timetal 21S and Ti 6Al-4V). The fatigue crack growth rate (da/dN) of Ti 6-2-2-2-2 in laboratory air is dependent upon stress ratio (R), particularly in the near-threshold and lower-Paris regimes. For low R (less than approximately 0.5), da/dN is influenced by crack closure behavior. At higher R (> 0.5), a maximum stress-intensity factor (K(sub max)) dependence is observed. Fatigue crack growth behavior is affected by test temperature between 24 and 177 C. For moderate to high applied cyclic-stress-intensity factors (delta-K), the slope of the log da/dN versus log delta-K curve is lower in 177 C laboratory air than 24 C laboratory air. The difference in slope results in lower values of da/dN for exposure to 177 C laboratory air compared to room temperature laboratory air. The onset of this temperature effect is dependent upon the applied R. This temperature effect has not been observed in ultrahigh vacuum. Specimen orientation has been shown to affect the slope of the log da/dN versus log delta-K curve in the Paris regime.Smith, Stephen W. and Piascik, Robert S.Langley Research CenterCRACK PROPAGATION; FATIGUE (MATERIALS); TITANIUM ALLOYS; CORROSION; STRESS RATIO; TEMPERATURE EFFECTS; CRACK CLOSURE; STRESS INTENSITY FACTORS