Fractography

About: Fractography is a research topic. Over the lifetime, 5043 publications have been published within this topic receiving 86068 citations.

Mechanical properties and fracture of in-situ Al3Ti particulate reinforced A356 composites

Abstract: The microstructure and mechanical properties of in-situ 5 vol. % Al3Ti/A356 composites were studied either taking account of the effects of T6 heat treatment and strontium (Sr) addition or not. For both as-cast and T6 treated composites, the in-situ Al3Ti particulates are in a blocky morphology with average size of 5–6 μm. Sr modified the Si particulates by reducing their size and aspect ratio, without a noticeable influence on the Al3Ti particulates. Energy dispersive X-Ray spectroscopy (EDS) revealed the existence of Si in the blocky Al3Ti particulates in the as-cast composites likely to form an (Al,Si)3Ti phase. Solutionization at 540 °C for 4 h resulted in the enrichment of Si inside the Al3Ti particulates, raising a question about the stability of (Al,Si)3Ti as reported by others. For both as-cast and T6 treated A356 alloy, the yield strengths were enhanced by in-situ Al3Ti particles, but the elongation was adversely affected. In comparison, the tensile strength and ductility of the Al3Ti/A356 were simultaneous improved with the modification of Sr due mainly to the modification of eutectic Si particles. Microstructure-based representative volume element (RVE) simulations revealed the microscale damage evolution of the studied materials and provided a good prediction of their fracture behavior, substantiated by fractography.

Fatigue Properties of Wood in Tension, Compression and Shear

Abstract: The fatigue properties of wood laminates have been investigated in tension, compression and shear Fatigue lives in compression are significantly less than in tension, and S-N data at five R ratios has yielded a set of constant-life lines, the form of which is related to the failure mode of the wood observed by scanning electron microscopy A point of inflection in the constant-life lines at the transition between all compressive and partially tensile fatigue loading is a new observation S-N curves for wood laminates have been produced for shear across the radial-longitudinal and tangential-longitudinal planes, and the latter plane is observed to be more resistant to fatigue loads Samples with four times the cross-sectional area of standard-sized samples have been fatigued at R=−1 and no significant difference in fatigue life is apparent It appears that the absence of a size effect in tension-compression results from the orthotropic structure of wood which is insensitive to variations in the density of surface flaws

Anisotropic fracture behaviour of cold drawn steel: a materials science approach

Abstract: In this paper the fracture performance of axisymmetric notched samples taken from pearlitic steels with different levels of cold drawing is studied. To this end, a real manufacture chain was stopped in the course of the process, and samples of all intermediate stages were extracted. Thus the drawing intensity or straining level (represented by the yield strength) is treated as the fundamental variable to elucidate the consequences of the manufacturing route on the posterior fracture performance of the material. A materials science approach to the phenomenon is proposed, so that the strongly anisotropic fracture behaviour of the steels with high level of strain hardening (which exhibit a 90° step in the fracture surface) is rationalized on the basis of the markedly oriented pearlitic microstructure of the drawn steels which influences the operative micromechanism of fracture in this case.