Stereoscopic Analysis of the Stretch Zone of a Steel Specimen Cut Out of a Railway Axle and Tested for Static Fracture T
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TECHNICAL ARTICLE—PEER-REVIEWED
Stereoscopic Analysis of the Stretch Zone of a Steel Specimen Cut Out of a Railway Axle and Tested for Static Fracture Toughness P. O. Maruschak • A. P. Sorochak I. V. Konovalenko
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Submitted: 29 January 2015 / in revised form: 13 February 2015 / Published online: 26 March 2015 ASM International 2015
Abstract The method for determining the height of the surface microirregularities by means of a pseudostereopair, which can be used to determine the geometry of the start zone of the brittle separation crack, is completed and automated. The possibility of using the proposed method for investigating the stretch zone of compact specimens of the OSL steel is considered. The stretch zone of the railway axis steel is investigated using the proposed technique. Keywords Stretch zone Scanning electron microscope Failure mechanism
Introduction Safe operation of wheel-set axles requires continuous monitoring of their technical condition and intensive work on the evaluation of their residual life and possibilities for its extension [1–3]. Previous experience with the evaluation of current technical condition of wheel-set axles shows that the main reason for failure of the equipment is fatigue degradation of high-strength steels [4, 5]. Such phenomena occur under general influence of the long-term mechanical operation processes. The activation of deformation processes preconditions their localization and further material damage, the mechanisms of which can be evaluated based on the analysis of the material fractures and natural structures, i.e., based on fractodiagnostics results [4]. At present, the approaches of fractodiagnostics have become a frequent P. O. Maruschak (&) A. P. Sorochak I. V. Konovalenko Ternopil Ivan Pul’uj National Technical University, Ternopil, Ukraine e-mail: [email protected]
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practice in expert evaluation of the reasons for degradation of heavy-duty structures: moreover, they are being complemented and developed with a view to automation of research, increasing the accuracy of the methods used and decreasing their complexity [6, 7]. In our opinion, the most informative of all the methods applicable to fractodiagnostics are the methods for reproduction of 3D images of the surface analyzed, including stereometric methods, which allow obtaining additional information about the reasons for degradation of the material analyzed [8, 9]. Despite a significant number of the methods for processing digital images of the surface and drawing conclusions about its condition, the development of a universal and effective approach to the secondary processing of informative data on the fractographic analysis remains a topical task at present. Using pseudostereometric analysis allows, based on the analysis of several photo images made successively, reproducing the height of the surface relief, i.e., obtaining additional data about the object studied [10]. However, on the whole, this problem is studied insufficiently for the evaluation of the fracture surface parameters
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