The subject of fractography was first addressed in a Metals Handbook volume in 1974. Volume 9 of the 8th Edition, Fractography and Atlas of Fractographs, provided systematic and comprehensive treatment of what was at that time a relatively new body of knowledge derived from examination and interpretation of features observed on the fracture surfaces of metals. The 8th Edition volume also documented the resurgence of engineering and scientific interest in fracture studies, which was due largely to the development and widespread use of the transmission electron microscope and the scanning electron microscope during the 1960s and early '70s.
During the past 10 to 15 years, the science of fractography has continued to mature. With improve methods for specimen preparation, advances in photographic techniques and equipment, the continued refinement and increasing utility of the scanning electron microscope, and the introduction of quantitative fractography, a wealth of new information regarding the basic mechanisms of fracture and the response of materials to various environments has been introduced. This new volume presents in-depth coverage of the latest developments in fracture studies.
Like its 8th Edition predecessor, this Handbook is divided into two major sections. The first consists of nine articles that present over 600 photographic illustrations of fracture surfaces and related microstructural features. The introductory article provides an overview of the history of fractography and discusses the development and application of the electron microscope for fracture evaluation. The next article, “Modes of Fracture,” describes the basic fracture modes as well as some of the mechanisms involved in the fracture process, discusses how the environment affects material behavior and fracture appearance, and lists material defects where fracture can initiate. Of particular interest in this article is the section “Effect of Environment on Fatigue Fracture,” which reviews the effects of gaseous environments, liquid environments, vacuum, temperature, and loading on fracture morphology.
The following two articles contribute primarily to an understanding of proper techniques associated with fracture analysis. Care, handling, and cleaning of fractures, procedures for sectioning a fracture and opening secondary cracks, and the effect of nondestructive inspection on subsequent evaluation are reviewed in “Preparation and Preservation of Fracture Specimens.”“Photography of Fractured Parts and Fracture Surfaces” provides extensive coverage of proper photographic techniques for examination of fracture surfaces by light microscopy, with the emphasis on photomacrography.
The value of fractography as a diagnostic tool in failure analyses involving fractures can be appreciated when reading “Visual Examination and Light Microscopy.” Information on the application and limitations of the light microscope for fracture studies is presented. A unique feature of this article is the numerous comparisons of fractographs obtained by light microscopy with those obtained by scanning electron microscopy.
The next article describes the design and operation of the scanning electron microscope and reviews the application of the instrument to fractography. The large depth of field, the wide range of magnifications available, the simple nondestructive specimen preparation, and the three-dimensional appearance of SEM fractographs all contribute to the role of the scanning electron microscope as the principal tool for fracture studies (Fig. 1).
Comparison of light microscope (top row) and scanning electron microscope (bottom row) fractographs showing the intergranular fracture appearance of an experimental nickel-base precipitation-hardenable alloy rising-load test specimen that was tested in pure water at 95 °C (200 °F). All shown at 50×. Courtesy of G.F. Vander Voort and J.W. Bowman, Carpenter Technology Corporation. Additional comparisons of fractographs obtained by light microscopy and scanning electron microscopy can be found in the article “Visual Examination and Light Microscopy” in this Volume.
Comparison of light microscope (top row) and scanning electron microscope (bottom row) fractographs showing the intergranular fracture appearance of an experimental nickel-base precipitation-hardenable alloy rising-load test specimen that was tested in pure water at 95 °C (200 °F). All shown at 50×. Courtesy of G.F. Vander Voort and J.W. Bowman, Carpenter Technology Corporation. Additional comparisons of fractographs obtained by light microscopy and scanning electron microscopy can be found in the article “Visual Examination and Light Microscopy” in this Volume.
Although the transmission electron microscope is used far less today for fracture work, it remains a valuable tool for specific applications involving fractures. These applications are discussed in the article “Transmission Electron Microscopy,” along with the various techniques for replicating and shadowing a fracture surface. A point-by-point comparison of TEM and SEM fractographs is also included.
Quantitative geometrical methods to characterize the nonplanar surfaces encountered in fractures are reviewed in the articles “Quantitative Fractography” and “Fractal Analysis of Fracture Surfaces.” Experimental techniques (such as stereoscopic imaging and photogrammetric methods), analytical procedures, and applications of quantitative fractography are examined.
An Atlas of Fractographs constitutes the second half of the Handbook. The 270-page Atlas, which incorporates 31 different alloy and engineered material categories, contains 1343 illustrations, of which 1088 are SEM, TEM, or light microscope fractographs. The remainder are photographs, macrographs, micrographs, elemental dot patterns produced by scanning Auger electron spectroscopy or energy-dispersive x-ray analysis, and line drawings that serve primarily to augment the information in the fractographs. The introduction to the Atlas describes its organization and presentation. The introduction also includes three tables that delineate the distribution of the 1343 figures with respect to type of illustration, cause of fracture, and material category.
Join ASM International
Being a member of the world’s largest association of materials professionals provides the benefits and resources you need to accomplish your personal and professional goals.
