Topic
Fractography
About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.
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TL;DR: The hypothesis that the KA of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure is tested andimation of interfacial toughness was feasible by fracture mechanics and fractography.
Abstract: We suggest that the apparent interfacial fracture toughness (KA) may be estimated by fracture mechanics and fractography This study tested the hypothesis that the KA of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/or silane (S), followed by an adhesive resin Microtensile test specimens (n = 30; area of 1 ± 001 mm2) were indented (98 N) at the interface and loaded to failure in tension We used tensile strength (σ) and the critical crack size (c) to calculate KA (KA = Yσc1/2) (Y = 165) ANOVA and Weibull analyses were used for statistical analyses Mean KA (MPa·m1/2) values were: (E1HF) 026 ± 006; (E1S) 023 ± 006; (E1HFS) 030 ± 006; (E2HF) 031 ± 006; (E2S) 013 ± 005; and (E2HFS) 041 ± 007 All fractures originated from indentation sites Estimation of interfacial toughness was feasible by fracture mechanics and fractogra
46 citations
TL;DR: In this article, the hydrogen effect on crack growth behavior in a type 304 austenitic stainless steel was investigated and the following results were obtained: the crack growth rate in hydrogen gas is accelerated compared with that in air.
Abstract: The hydrogen effect on crack growth behaviour in a type 304 austenitic stainless steel was investigated and the following results were obtained. The crack growth rate in hydrogen gas is accelerated compared with that in air. In order to clarify the mechanism of the acceleration, the growth behaviours of a crack propagating in a grain and propagating along the boundary to be a fracture facet were investigated. Slip behaviour, opening displacement and fractography showed that the slip-off mechanism in fatigue crack growth is valid even in hydrogen gas. Hydrogen mainly affects slip behaviour such that slip bands concentrate at a crack tip and result in acceleration of the growth rate. The facets are not significantly responsible for the acceleration. The ratio of facets to the entire area is low, and a crack nearly compensates for the temporary acceleration by the facets with subsequent deceleration.
46 citations
TL;DR: In this paper, a model is developed that quantitatively predicts fracture surface roughness and roughness-induced crack closure stress intensity values from measurements of slip line spacing in a compression specimen.
46 citations
01 Mar 2013-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the fatigue behavior of the friction stir spot welded (FSSW) coupons of magnesium AZ31 alloy manufactured under different welding process conditions is investigated, and two sets of lap-shear coupons were made based on variation in plunge depth, tool rotation speed and tool geometry.
Abstract: In this paper the fatigue behavior of the friction stir spot welded (FSSW) coupons of magnesium AZ31 alloy manufactured under different welding process conditions is investigated. Two sets of lap-shear coupons were made based on variation in plunge depth, tool rotation speed and tool geometry. Metallographic analysis of the untested FSSW coupons revealed differences in weld geometry and microstructure. Interfacial hooking of the faying surface was found to vary significantly between the two sets of process conditions. Microhardness test data revealed a large gradient in hardness profile. Results from the load controlled cyclic tests showed that lower tool rotation and shallower shoulder plunge depth led to better fatigue performance. Optical fractography of the fatigued coupons revealed that fatigue cracks initiated at the weld interface in both sets of coupons. However, the fracture mode showed variability between the two process conditions. The fractography analysis suggests that the effective top sheet thickness, interfacial hook and microstructure, which are largely determined by the process conditions, significantly affect the fatigue behavior of the friction stir spot welds in magnesium alloys.
46 citations
TL;DR: In this article, a study has been conducted to characterize the fatigue crack growth rates and mechanisms in thin and thick plate commercial 7050-T7451 aluminum plate in the L-S orientation.
46 citations