Damage Assessment Using Fractography as Failure Surface Evaluation: Applications in Industrial Metalworking Machinery
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Damage Assessment Using Fractography as Failure Surface Evaluation: Applications in Industrial Metalworking Machinery George A. Pantazopoulos
Submitted: 9 July 2011 / Published online: 13 August 2011 ASM International 2011
Abstract Fractography is a powerful analytic tool for the evaluation of failure surface topography and root-cause analyses. Fractography, embracing both light and electron optics methods, is utilized in modern failure analysis and is recognized by the engineering community as a unique process for industrial problem solving, evaluating machinery/component failures, and providing solutions for performance improvements. In the present study, the role of fractography is highlighted through characteristic failures of industrial machinery components. Low-power stereomicroscopy and Scanning Electron Microscopy (SEM) micro-fractography are the principal analytic tools that were used in the context of the present research. Keywords Macrofractography Microfractography Metalworking machinery Fatigue Overload
Introduction and Background Information Fractography etymologically originates from Latin fractus meaning fracture and the Greek graphy (Greek: cqa9ux) meaning writing, and by extending this term to the meaning describing, it, therefore, means a description of the fracture; see also Ref. [1]. The historic evolution of fractography and its contribution to the determination of failure modes were addressed in Ref. [2]. Apart from industrial applications, fractographic techniques are frequently used in forensic engineering and safety sectors
G. A. Pantazopoulos (&) ELKEME Hellenic Research Centre for Metals S.A., 252 Piraeus Street, 17778 Athens, Greece e-mail: [email protected]
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aiming toward accident prevention. Fractographic assessment used in the field of materials and manufacturing engineering, has made significant advances, since it contributes mainly to the progresses in the following areas; see also Ref. [3]: • • •
Basic understanding of physics and micromechanics of fracture. Material’s improvement in terms of resistance to deformation and damage. Analyses of crack evolution and failure history in rootcause investigation.
Numerous practical applications of fractography in the industrial field were also presented in Refs. [4, 5]. Fractographic interpretation has been acknowledged for its significant impact to the society for many decades. Fractography is often used in combination with microstructurecharacterization techniques (light and scanning electron microscopy) in the majority of material failure analysis research projects [6–11]. Low-power stereomicroscopy (magnifications up to approximately 925), under vertical or oblique light illumination is the first approach in fracture evaluation, called macrofractography. Sequentially, microfractographic investigation is carried out preceded by Scanning Electron Microscopy (SEM) employing secondary and/or backscattered electron-imaging modes for topographic and compositional evaluations. Energy Dispersive Spectrometry
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