Topic
Fractography
About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.
Papers published on a yearly basis
Papers
More filters
25 Feb 2006-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, an Mg AZ31 alloy with modified microstructures was investigated to determine microstructural effects on room temperature mechanical properties acquired from low strain rate (∼10 −3 ǫs −1 ) tensile testing to failure.
Abstract: An Mg AZ31 alloy with modified microstructures was investigated to determine microstructural effects on room temperature mechanical properties acquired from low strain rate (∼10 −3 s −1 ) tensile testing to failure. Three distinct microstructures were generated via heat treatment, viz.: (1) single phase, fine equiaxed grains; (2) single phase, coarse grains with twins; (3) fine, equiaxed grains decorated with Mg 17 (Al,Zn) 12 grain-boundary precipitates. Each microstructure was separately characterized with optical microscopy, X-ray crystallography, fractography, and hardness measurement prior to tensile testing. Tensile coupons fabricated from each microstructure were then elongated to failure in a miniature stage, and true stress–true strain curves were computed with the digital image correlation (DIC) technique. Initial yield point, ultimate tensile strength and maximum elongation were also computed and examined within the context of key features of each microstructure to infer the mechanism of plastic deformation in tension and whether or not the potential for improved room temperature formability exists.
145 citations
01 Jan 2011
TL;DR: In this article, the relative importance of these mechanisms for different fracture modes and materials are discussed based on detailed fractographic observations and critical experiments, and the evidence supporting various hypotheses, such as those based on hydride-formation, hydrogenenhanced decohesion, hydrogen-enhanced localised plasticity, adsorption-induced dislocation- emission, and hydrogen-vacancy interactions, are summarised.
Abstract: Mechanisms of hydrogen embrittlement in steels and other materials are described, and the evidence supporting various hypotheses, such as those based on hydride-formation, hydrogen-enhanced decohesion, hydrogen-enhanced localised plasticity, adsorption-induced dislocation- emission, and hydrogen-vacancy interactions, are summarised. The relative importance of these mechanisms for different fracture modes and materials are discussed based on detailed fractographic observations and critical experiments.
144 citations
TL;DR: In this article, the authors examined hydrogen embrittlement in FeSi-and Ni-single crystals at low hydrogen pressures (10 mPa ⩽ pH2⩽ 100 kPa) and measured the crack tip opening angle α of a growing crack as a function of temperature, hydrogen pressure and rate.
143 citations
TL;DR: In this article, it is hypothesized that the cracklike internal surfaces are developed as a result of differential sintering of agglomerates relative to their surrounding powder compact, and isostatic hot-pressing of the sintered composites quickly eliminated the crack-like internal surface.
Abstract: Strengths of sintered Al2O3/ZrO2 composites are much lower than those of hot-pressed composites due to large flaws associated with the sintering process. Fractography has shown that cracklike internal surfaces are at the fracture origins of the sintered materials. It is hypothesized that the cracklike internal surfaces are developed as a result of differential sintering of agglomerates relative to their surrounding powder compact. Isostatic hot-pressing of the sintered composites quickly eliminated the cracklike internal surface. Flaws responsible for fracture of the isostatically hot-pressed composites were low-density regions that are not as easily eliminated.
143 citations
TL;DR: In this article, the CTOA values during stable tearing were measured by two independent methods, optical microscopy and digital image correlation, for 2.3mm thick sheets of 2024-T3 aluminum alloy.
Abstract: The stable tearing behavior of 2.3-mm thick sheets of 2024-T3 aluminum alloy was experimentally investigated for middle crack tension specimens having initial flaws that were: (a) flat fatigue cracks (low fatigue stress) and (b) 45-deg through-thickness slant cracks (high fatigue stress). The critical CTOA values during stable tearing were measured by two independent methods, optical microscopy and digital-image correlation. Results from the two methods agree well. The CTOA measurements and observations of the fracture surfaces have shown that the initial stable tearing behavior of low and high fatigue stress tests is significantly different. The cracks in the low fatigue stress tests underwent a transition from flat-to-slant crack growth, during which the CTOA values were high and significant crack tunneling occurred. After crack growth equal to about the thickness (Δa>B), CTOA reached a constant value of 6 deg and after crack growth equal to about twice the thickness (Δa>2B), crack tunneling stabilized. The cracks in the high fatigue stress tests reach the same constant CTOA value after crack growth equal to about the thickness, but produced only slightly higher CTOA values during initial crack growth. The amount of tunneling in the high fatigue stress tests was about the same as that in the low fatigue stress tests after the flat-to-slant transition. This study indicates that stress history has an influence on the initial portion of the stable tearing behavior. The initial high CTOA values, in the low fatigue crack tests, coincided with large three-dimensional crack front shape changes due to a variation in the through-thickness crack-tip constraint. The measured CTOA reached a constant value of 6 deg for crack growth of about the specimen thickness. This coincided with the onset of 45-deg slant crack growth and a stabilized, slightly tunneled (about 20 percent of the thickness) crack-front shape. For crack growth on the 45-deg slant, the crack front and local field variables are still highly three dimensional.
142 citations