Download Free The Micromechanicsms Of Cleavage Fracture And Their Relationship To Fracture Toughness In A Bainitic Low Alloy Steel Book in PDF and EPUB Free Download. You can read online The Micromechanicsms Of Cleavage Fracture And Their Relationship To Fracture Toughness In A Bainitic Low Alloy Steel and write the review.

In this book the authors focus on the description of the physical nature of cleavage fracture to offer scientists, engineers and students a comprehensive physical model which vividly describes the cleavage microcracking processes operating on the local (microscopic) scale ahead of a defect. The descriptions of the critical event and the criteria for cleavage fracture will instruct readers in how to control the cleavage processes and optimize microstructure to improve fracture toughness of metallic materials. - Physical (mechanical) processes of cleavage fracture operating on the local (microscopic) scale, with the focus on the crack nucleation and crack propagation across the particle/grain and grain/grain boundaries - Critical event, i.e., the stage of greatest difficulty in forming the microcrack, which controls the cleavage fracture - Criteria triggering the cleavage microcracking with incorporation of the actions of macroscopic loading environment into the physical model - Effects of microstructure on the cleavage fracture, including the effects of grain size, second phase particles and boundary - Comprehensive description of the brittle fracture emerging in TiAl alloys and TiNi memory alloys
The tensile properties and fracture toughness were measured in sheet material for isothermally transformed lower bainite and tempered martensite in a series of alloy steels. The major experimental variables were transformation temperature, tempering temperature, carbon content, and alloy additions. Carbon contents of 0.55 to 0.60% or higher are required to develop ultra-high strength levels in lower bainite. Lower bainite with yield strengths above 220,000 psi had slightly to moderately lower fracture toughness than tempered martensite in typical low alloy steels at comparable yield strengths. At yield strengths below 220,000 psi, lower bainite was equal to or slightly better than tempered martensite in typical low alloy steels, except the 1Cr-1Mo composition which is superior to the other alloy steels studied at yield strengths up to 240,000 psi. The fracture toughness of lower bainite is discussed in terms of transformation temperature, M sub s temperature, and steel composition. A 9Ni-4Co steel developed an atypical bainitic microstructure at transformation temperatures just above the M sub s temperature.
Using precracked Charpy tests supplemented by center-notched tensile tests, the fracture toughness of five low-alloy and three stainless steel high-strength alloys in sheet form was measured primarily as a function of heat treatment variables such as austenitizing and tempering temperatures. The low alloy steels studied were D6AC (two heats)4340 (martensitic and bainitic conditions), X200 (0.35 and 0.40% carbon), 300M and H11; and the stainless steels were AM 355, PH 15-7Mo and 301. For 4340, in the bainitic condition, the influence of subsequent deformation and aging on fracture toughness was also determined. In addition, preliminary studies of the effect of welding both before and after heat treatment on the toughness of H11, 300M and 4340 were carried out. (Author).
Fracture and Fatigue: Elasto-Plasticity, Thin Sheet and Micromechanisms Problems covers the proceedings of the Third Colloquium on Fracture. The book discusses the development and applications of fracture mechanics. The contents of the text are organized according to the areas of concerns. The first part deals with elasto-plastic fracture mechanics, which includes topics such as fracture mechanics in the elastic-plastic regime and sizing of the geometry dependence and significance of maximum load toughness values. Part II covers the micromechanisms of fracture, which includes the aspects of crack growth under monotonic loading and the effect of secondary hardening on the fracture toughness of a bainitic microstructure. Part III concerns itself with thin sheet fracture mechanics, which includes R-curves evaluation for center-cracked panels and use of the R-curve for design with contained yield. The book will be of great interest to researchers and professionals whose work involves fracture mechanics.
Advances in Research on the Strength and Fracture of Materials: Volume 1s—An Overview contains the proceedings of the Fourth International Conference on Fracture held at the University of Waterloo, Canada, in June 1977. The papers review the state of the art with respect to fracture in a wide range of materials such as metals and alloys, polymers, ceramics, and composites. This volume is comprised of 40 chapters and opens with a discussion on progress in the development of elementary fracture mechanism maps and their application to metal deformation processes, along with micro-mechanisms of fracture and the fracture toughness of engineering alloys. The next section is devoted to the fracture of large-scale structures such as steel structures, aircraft, cargo containment systems, nuclear reactors, and pressure vessels. Fracture at high temperatures and in sensitive environments is then explored, paying particular attention to creep failure by cavitation under non-steady conditions; the effects of hydrogen and impurities on brittle fracture in steel; and mechanism of embrittlement and brittle fracture in liquid metal environments. The remaining chapters consider the fracture of non-metallic materials as well as developments and concepts in the application of fracture mechanics. This book will be of interest to metallurgists, materials scientists, and structural and mechanical engineers.
This report deals with the relationship of elements of microstructure to the fracture characteristics of a group of commercially produced steels, heat-treated to ultra-high strength levels. The microstructures were characterized in terms of optical microscopy, electron diffraction, and electron fractography. Fractographic studies were made of fractured surfaces broken in impact at +25 and -196 C as a function of tempering temperature, in slow bending at ambient temperature, in a modified bend test in which slow and fast propagation stages were effected, and on surfaces produced in tensile fractures. The fracture characteristics were studied by means of an instrumented bend test and in terms of the plastic instability generated in the torsion test. The instrumented bend test yielded data on criteria for the onset of slow crack propagation and for the onset of rapid propagation, including the effect of the total stored energy in the system. Plastic instability in torsion was studied as a function of specimen section size in AISI 4340 steel. A 250,000 psi yield strength Maraging steel was studied in a standard size test bar. (Author).