Download or read book Investigation of Adiabatic Shear Bands in Commercial Purity Titanium and Ti 6Al 4V Alloy written by William R. Lonardo and published by . This book was released on 1991 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation of Dual Phase Titanium Alloys written by Jikang Zhong and published by . This book was released on 2012 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: The deformation behaviour of dual phase titanium alloys has been investigated using experimental and modelling methods. The motivation for conducting this investigation was to improve understanding of the deformation behaviour of dual phase titanium alloys in order to contribute to the long term goal of reducing manufacturing cost and improving production efficiency. Dual phase titanium alloys have been studied under two deformation conditions: high speed machining and uniaxial compression, which represent respectively high rate and low rate deformation. The microstructure and texture of the serrated chips obtained during high speed cutting of the dual phase Ti-6Al-4V alloy have been studied. The cutting speed, depth of cut and the orientation of the sample were found to have a significant influence on the deformation of serrated chips. Adiabatic shear bands were found in the serrated chips due to non-uniform deformation of Ti-6Al-4V alloy and deformation heating. In addition, there is reasonable agreement between the predicted texture using the visco-plastic self-consistent (VPSC) model and the measured texture using the electron backscatter diffraction (EBSD) technique indicating that the deformation in an adiabatic shear band is due to shear.The deformation behaviour of dual phase Ti-Mn alloys has been characterised with uniaxial compression at different temperatures and strain rates. The flow stress plateau phenomenon was observed in all the Ti-Mn alloys in the low to medium temperature range (27~500°C), which is attributed to the occurrence of dynamic strain aging (DSA). The flow softening behaviour was observed in dual phase Ti-Mn alloys in the high to sub-transus temperature range (600~800°C), which is attributed to the change in volume fraction of [beta] phase during deformation due to the rise in temperature caused by deformation heating. The yield point phenomenon was observed when the Ti-Mn alloys are above their [beta] transus temperatures. This phenomenon has been attributed to the multiplication of dislocations at the beginning of plastic deformation and dynamic recovery in the following plastic deformation. The strain rate sensitivity of Ti-Mn alloys was low in the low to medium temperature range and thus the effect of strain rate on deformation is not obvious. However, it was high in the high to sub-transus temperature range and thus the effect of strain rate on the deformation is significant. The 0.2% proof stress was found to increase with the volume fraction of [beta] phase. The strain rate sensitivity was found to decrease with the volume fraction of [beta] phase in the low to medium temperature range because the strain rate sensitivity of the [alpha] phase is higher than the [beta] phase. However, the strain rate sensitivity was found to increase with the volume fraction of [beta] phase at high temperatures because the strain rate sensitivity of the [beta] phase becomes larger than the [alpha] phase. A considerable temperature rise was observed during compression of the Ti-Mn alloys and this indicates that the effect of deformation heating on deformation is not negligible. A composite model has been constructed to predict the plastic stress-strain curves of the dual phase Ti-Mn alloys using the in-situ behaviour of the component phases. The partition of stress and strain between the component phases has been accounted for by using three partitioning assumptions: iso-strain, iso-stress and iso-work. There was good agreement between the predicted curves and the experimental curves. It was found that the in-situ behaviour of the [alpha] phase is different in different dual phase Ti-Mn alloys and it exhibits a linear relationship with the volume fraction of [beta] phase when the dominant matrix is the same. The modelling results in the low to medium temperature range indicate that most of the plastic deformation occurs in the localised shear band, which is consistent with the experimental observation that the dual phase Ti-Mn alloys were more susceptible to the formation of localised shear bands. In addition, it was found that a change in the dominant matrix in dual phase Ti-Mn alloys significantly influences the in-situ behaviour of the [alpha] phase. The modelling results in the high to sub-transus temperature range indicate that the flow softening behaviour observed in dual phase Ti-Mn alloys is related to the change in volume fraction of the [beta] phase and the diffusion of Mn during the deformation.

Download or read book Proceedings of the 13th World Conference on Titanium written by Vasisht Venkatesh and published by John Wiley & Sons. This book was released on 2016-04-26 with total page 2004 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the Proceedings of the 13th World Conference on Titanium.

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1985 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Formation of Adiabatic Shear Bands by Ballistic Impact in a Titanium Alloy written by S. P. Timothy and published by . This book was released on 1983 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the though that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemi nation. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 37 (thesis year 1992) a total of 12,549 thesis titles from 25 Canadian and 153 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 37 reports theses submitted in 1992, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

Download or read book Dynamic Behavior of Two Advanced Materials written by Zezhou Li and published by . This book was released on 2019 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic deformation occurs when bodies are subjected to rapidly changing loads and can differ significantly from deformation that occurs under static or quasi-static situations. It is of great significance to understand the deformation and failure mechanisms of advanced materials, and there are potential applications in which dynamic deformation and failure can occur. Two classes of advanced materials, ultrafine-grained (UFG) (~500 nm and ~100 nm) titanium and high-entropy alloys (HEAs) (Al0.3CoCrFeNi and CoCrFeMnNi) are the focus of this doctoral investigation. The deformation and adiabatic shear localization at cryogenic temperatures (173 K and 77 K) in ultrafine-grained (100 and 500 nm) titanium are investigated. In comparison with conventionally-grained titanium, the strength of ultrafine-grained titanium is higher due to the classic Hall-Petch effect while the strain-hardening rate approaches zero. Our results show that shear localization in dynamic deformation is also altered. The width of the shear band of coarse-grained titanium decreases from 30 [mu]m at 293 K to 18 [mu]m at 77 K (a 40% decrease). In contrast, for 100 nm titanium, the width of shear band decreases more significantly from 4 [mu]m at room temperature to 1 [mu]m (a 75% decrease) at cryogenic temperature (77 K). This difference is attributed to the combined effects of a decrease in the thermal conductivity and the specific heat capacity, and an increase in the thermal softening, which can lead to a band with thickness of 1 [mu]m. These changes agree with the predictions of the Grady and Bai-Dodd theories. The dislocation evolution and the subgrain rotation mechanisms responsible for forming ultrafine- and nano- recrystallized grains are modeled. In addition, the Zener-Hollomon parameter is incorporated in the analysis to predict the critical dislocation density for shear localization and the recrystallized grain size in titanium . The mechanical behavior of three single-phase face-centered-cubic (fcc) Al0.3CoCrFeNi, annealed CoCrFeMnNi and as-processed CoCrFeMnNi high-entropy alloys (HEAs) was studied in both quasi-static and high strain-rate regimes. Based on Hall-Petch strengthening, solid-solution strengthening, order hardening, cutting forest dislocations, and twinning hardening mechanisms, a constitutive equation was proposed to describe the flow of the annealed CoCrFeMnNi high-entropy alloy under dynamic impact. The resistance to shear localization is being established by dynamically-loading hat-shaped specimens that induce forced shear localization. Adiabatic shear band formation required an imposed shear strain of ~7 for the annealed CoCrFeMnNi HEA and cannot be observed at a strain of 1.1 for the Al0.3CoCrFeNi HEA. The structural and mechanical response that give rise to a remarkable resistance to shear localization are characterized by a combination of (1) a high strain-hardening ability, enabled by solid solution hardening, forest dislocation hardening, order hardening, and twinning hardening, (2) a high strain-rate sensitivity and (3) modest thermal softening; these combination effects give rise to the remarkable resistance to shear localization. First, the low stacking-fault energies in as-received high-entropy alloys lead to the formation of twinned segments inside the coarse grains. Then, when the thermal softening overcomes strain hardening, the shear bands would form, and dynamic recrystallization occurs inside the segments for the further break-up of the grains. Classical Straker equation is applied to predict the critical shear strain for shear localization, which was quite comparable to the experimental values in the high-entropy alloys. It was revealed that the as-processed CoCrFeMnNi HEA was prone to shear localization due to the initially high dislocation density which results in a relatively low work-hardening effect. The dynamic deformation of these two metallic materials leads to adiabatic shear band formation at extreme shear strains. The resultant of the ultrafine grain structure observed in these two materials with diverse structures (HCP for Ti and FCC for HEAs) is remarkably similar and reinforces the concept of rotational dynamic recrystallization as the mechanism responsible for localization.

Download or read book Introduction To Adiabatic Shear Localization Revised Edition written by Bradley Dodd and published by World Scientific Publishing Company. This book was released on 2014-08-14 with total page 469 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adiabatic shear bands are found in a variety of metals and other materials; they cause rapid weakening due to energy concentration into narrow regions of the material. This is the very first book on this important topic and the only true introduction to the subject. An enhanced and updated student-friendly edition of the authors' 1992 book Adiabatic Shear Localization: Occurrence, Theories and Applications, this seminal text now includes essential Further Reading sections in some chapters. It explains adiabatic shear bands in a descriptive rather than a mathematical way, with a ‘quick reference’ section for readers wanting a more rapid introduction. Entirely comprehensive, the reader can dip into the chapters as suits his or her course material or research.If you are a postgraduate materials scientist, engineer, physicist, metallurgist, or indeed any researcher in materials that undergo rapid deformation and failure, this text is not to be missed.

Download or read book Metals Abstracts written by and published by . This book was released on 1994 with total page 1584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adiabatic Shear Bands in Simple and Dipolar Plastic Materials written by Thomas W. Wright and published by . This book was released on 1987 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Omega Phase Formation in Titanium and Titanium Alloys written by and published by . This book was released on 1992 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although the response of titanium alloys to dynamic loading is receiving increased attention in the literature (particularly in the area of shear-band formation), a more limited experimental database exists concerning the detailed structure/property relationships of titanium alloys subjected to shock loading. In this study, preliminary results concerning the influence of alloy chemistry on the property of omega-phase formation and its structure in three titanium alloys are presented. The influence of shock-wave deformation on the phase stability and substructure evolution of high-purity (low-interstitial) titanium, A-70 (3700 ppm oxygen) titanium, and Ti-6Al-4V were probed utilizing real-time velocity interferometry (VISAR) and soft'' shock-recovery techniques. VISAR wave profiles of shock-loaded high-purity titanium revealed the omega-phase pressure-induced transition to occur at approximately 10.4 GPa. Wave profile measurements on A-70 Ti shocked to pressures up to 35 GPa and Ti-6Al-4V shocked to pressures up to 25 GPa exhibited no evidence of a three-wave structure indicative of a pressure-induced phase transition. Neutron and X-ray diffractometry and TEM analysis confirmed the presence of retained [omega]-phase in the electrolytic-Ti and the absence of [omega]-phase in the shock-recovered A-70 Ti and Ti-6Al-4V. Suppression of the [alpha]-[omega] phase transition in A-70 Ti, containing a high interstitial oxygen content, is seen to simultaneously correlate with suppression of deformation twinning. Neutron diffraction was used to measure the in-situ bulk lattice constants and volume fraction of the [alpha] and [omega] phases in the recovered high-purity titanium samples that were shock loaded. The influence of alloy content on the kinetics of formation/retention of [omega]-phase and substructure evolution is discussed and contrasted in light of previous literature studies.

Download or read book Constitutive and Damage Modeling of Inelastic Deformation and Phase Transformation written by Akhtar S. Khan and published by . This book was released on 1998 with total page 1108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adiabatic Shear Band Formation in Titanium written by M. Laxmi Prasad and published by . This book was released on 1993 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Machining of Titanium Alloys written by J. Paulo Davim and published by Springer. This book was released on 2014-07-05 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 934 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Physics and Mathematics of Adiabatic Shear Bands written by T. W. Wright and published by Cambridge University Press. This book was released on 2002-07-22 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a research monograph on the material instability known as adiabatic shear banding which often occurs in a plastically deforming material as it undergoes rapid shearing. Plastic deformation generates heat, which eventually softens most materials with continued straining, a process which is usually unstable. In this case the instability results in thin regions of highly deformed material, which are often the sites of further damage and complete failure. The main body of the book examines a series of one-dimensional problems of increasing complexity. In this way a comprehensive and quantitative picture of the complete phenomena is built up. Particular care is taken to use well established asymptotic techniques to find simple, but universal, analytic expressions or scaling laws that encapsulate various aspects of the dynamic formation and the final morphology of shear bands. A fully developed mechanics of shear is just beginning to emerge as a major companion to fracture mechanics, this book may speed the process along.

Download or read book Microstructural Banding in Thermally and Mechanically Processed Titanium 6242 written by Utkarsh Kansal and published by . This book was released on 1992 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ti-6Al-2Sn-4Zr-2Mo-0.1Si specimens were shaped by repeated cycles of heating (to 954 °C) and hammer or press forging followed by a solution anneal that varied from 968 to 998 °C. The coupons were originally extracted from billets forged below the beta trans us (1009 °C) and slow cooled to ambient temperature. Macroscopic and microstructural banding is observed in some forged and solution annealed coupons, that consists of regions of elongated primary alpha. More significant banding is observed subsequent to annealing at lower temperatures (968 °C), whereas much less microstructural banding is present after annealing at higher temperatures (998 °C). About the same level of banding is observed in hammer forged and press forged coupons. The observation of these bands is significant since they may lead to inhomogeneous mechanical properties. Specifically, at least some types of banding are reported to affect the high temperature creep properties of this alloy. The origin of these bands was therefore researched. Classically, banding in Ti-6242-0.1Si has been regarded as a result of adiabatic shear, chill zone formation or compositional inhomogeneity. High and low magnification metallography, electron microprobe analysis and microhardness tests were performed on forged and annealed specimens in this investigation. The composition inside the bands appears identical to that outside of the bands. The fraction of primary alpha is also found to be identical. The bands have higher microhardness. These results suggest that the bands are not related to composition gradients. The bands also do not appear to be a result of adiabatic shear or other localized deformation. The bands of this study appear to originate from the elongated primary alpha microstructure of the forged billet (from which test coupons were extracted). The deformation of the extracted coupon may be neither fully homogeneous nor sufficiently substantial and the coupon is only partly statically restored after a solution anneal. Areas not fully restored appear as "bands" with elongated primary alpha, that are remnant of the starting billet microstructure. Therefore, a source of banding in Ti-6242-0.1Si alloy, additional to the classic sources, is evident. This type of banding is likely removed by relatively high solution treatment temperatures and perhaps greater plastic deformation during forging.