Download or read book Influences of Chemical and Thermal Environments on Delay in a Ti 6Al 4V Alloy written by TT. Shih and published by . This book was released on 1976 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influences of chemical and thermal environments on delay in fatigue crack growth under elemental load spectra were examined for a mill-annealed Ti-6Al-4V alloy. The results indicate that delay is significantly affected by the hold time at high load in 3.5 percent NaCl solution at room temperature, and by both temperature and thermal history. In 3.5 percent NaCl solution, delay may be increased by 40 times through increasing the hold time from zero to 900 s, the specific amount depends on the overload ratio (Khmax/Klmax) and the maximum value of the low-amplitude fatigue load (or Klmax. Delay is generally higher at the higher test temperature (560°F or 293°C), although the trend in behavior associated with changes in loading variables is similar to that observed at room temperature. Delay is significantly increased when the high load is applied at a high temperature, with subsequent fatigue at room temperature. It is reduced by intermediate heating at a high temperature following a high-load excursion at room temperature, and is lowest when fatigue loads are applied at high temperature following a high-load excursion at room temperature. The significance of these results in terms of modeling and life prediction procedures is discussed.
Download or read book Fatigue Crack Growth under Spectrum Loads written by and published by ASTM International. This book was released on 1976 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASTM Special Technical Publication written by and published by . This book was released on 1976 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture Mechanics written by Robert P. Wei and published by Cambridge University Press. This book was released on 2010-02-08 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture and 'slow' crack growth reflect the response of a material (i.e. its microstructure) to the conjoint actions of mechanical and chemical driving forces and are affected by temperature. There is therefore a need for quantitative understanding and modeling of the influences of chemical and thermal environments and of microstructure, in terms of the key internal and external variables, and for their incorporation into design and probabilistic implications. This text, which the author has used in a fracture mechanics course for advanced undergraduate and graduate students, is based on the work of the author's Lehigh University team whose integrative research combined fracture mechanics, surface and electrochemistry, materials science, and probability and statistics to address a range of fracture safety and durability issues on aluminum, ferrous, nickel, and titanium alloys and ceramics. Examples are included to highlight the approach and applicability of the findings in practical durability and reliability problems.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Journal of Materials Education written by and published by . This book was released on 1989 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts written by and published by . This book was released on 1993 with total page 1220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement and Analysis of Critical Crack Tip Processes During Fatigue Crack Growth written by and published by . This book was released on 1985 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ASTM Standardization News written by American Society for Testing and Materials and published by . This book was released on 1976 with total page 966 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environment Related Surface Phenomena and Their Influence on Properties of Ti 6Al 4V and Ti 6Al 2Sn 4Zr 2Mo Oxidation at Elevated Temperature and Corrosion During Chemical Treatment written by Birhan Sefer and published by . This book was released on 2017 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis covers investigation of the surface phenomena of Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo alloys related with oxidation at elevated temperature and corrosion during chemical treatment in hydrofluoric-nitric acid (HF/HNO3) solutions. The explored phenomena are related to manufacturing and service conditions of aero-engine components. During manufacturing and operation, the alloys are sunjected to elevated temperatures in oxygen environment. In such conditions an oxide on the surface and an oxygen enriched layer below the oxide, commonly referred as alpha-case is formed. Alpha-case is a hard and brittle layer that is detrimental to the mechanical properties and must therefore be completely eliminated. A conventional method for elimination of alpha-case is chemical processing in HF/HNO3 solutions, i.e. chemical milling. Isothermal oxidation treatments in air at 500, 593 and 700 oC for up to 500 hours were carried out in this thesis. Both alloys developed rutile type of oxide structure and Ti-6Al-2Sn-4Zr-2Mo exhibited stronger oxidation resistance than Ti-6Al-4V. Transition from parabolic to linear oxidation rate was observed at 700 oC and = 200 hours for both alloys. The difference in the oxidation kinetics of the two alloys is suggested to be related with the chemical composition of the alloys. The oxygen enriched layer, i.e. alpha-case layer, was characterised and its thickness was measured using conventional metallographic and microscopic techniques. The parabolic rate constants, the oxygen diffusion parameters and activation energies were estimated in the temperature range of 500-700 oC for both alloys. Moreover, the oxidation for 500 hours at 700 oC resulted in microstructural changes and element re-distribution. The bulk and alpha-case layer hardness at micro- and nano-scale were measured using microhardness and nanoindentation techniques. The alpha-case layer had higher hardness due to the solid solution strengthening effect of the diffused oxygen. The effect of chemical milling in 1:11 HF/HNO3 solution on the surface integrity, and the influence on low cycle fatigue (LCF) strength of cast Ti-6Al-2Sn-4Zr-2Mo alloy was investigated. Five and sixty minutes chemical processing times and three imposed total strain ranges in fatigue tests were evaluated. Significant drop in fatigue life was observed for the samples etched before LCF testing, as compared to the non-etched samples. The influence from etching was found to be most detrimental for fatigue samples tested at the lowest strain ranges. The fatigue life reduction was correlated with the number of crack initiation sites. Multiple crack initiation sites were observed for the etched samples, whereas only one crack initiation site was discerned in the non-etched samples. Inspection of the surface of the etched samples revealed selective and severely etched prior ß grain boundaries and pit formation at the triple joints of the prior ß grain boundaries. These surface defects were considered as stress raisers promoting an earlier fatigue crack initiation. The influence of two molar concentration ratios of HF and HNO3 acids (1:3 and 1:11) on the corrosion behaviour of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo were investigated by electrochemical and atomic force microscopy (AFM) techniques. The corrosion of the two alloys was a function of the concentration ratio of the acids and also of the alloys¿ chemical compositions. The AFM measurements showed faster dissolution rate of the a-phase than the ß-phase in the Widmanstätten microstructure. It was considered that the reason for this is formation of local micro-galvanic cells between the phases. Moreover, the Volta-potential was measured using scanning Kelvin probe force microscopy (SKPFM) and the obtained maps revealed difference in the Volta-potential between the a- and the ß-laths in both alloys. This observation strengthened the likelihood for formation and operation of micro-galvanic cells between the phases.
Download or read book CAB Current Awareness Bulletin written by and published by . This book was released on 1977 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts Index written by and published by . This book was released on 1978 with total page 1010 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 35th AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference written by and published by . This book was released on 1994 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Alloys Index written by and published by . This book was released on 1978 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of an International Conference on Prospects of Fracture Mechanics Held at Delft University of Technology the Netherlands June 24 28 1974 written by George C. Sih and published by . This book was released on 1975 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt:
