Fatigue fracture surface analysis in C45 steel specimens using X-Ray fractography

Abstract

X-Ray fractography is a useful technique to analyse the mechanisms operating in fracture and involves an examination of the fracture surface. In the present investigation, this technique has been employed to study the fatigue fracture behaviour of a medium carbon steel of C45 grade in different heat treated conditions. The different trends observed in the residual stress (a,) and diffraction profile full width at half maximum intensity (E) relationships with the maximum stress intensity factor (K,,,,,) on the fracture surface have been correlated to the differences in flow characteristics of these materials. The root mean square value of microstrain c, and the coherent domain (particle) size, D, were determined through single line diffraction profile (Voigt's) analysis. It has been observed that contribution of microstrain to profile broadening is more significant than that due to domain size. However, at higher K,,,,, values an influence of D was found on line broadening, to a small extent. Results of sub-surface stress measurements were compared in two conditions. A good correlation was noticed between the depths below the fracture surface, designated as y,,,, at which the measured or reaches the base material value and the corresponding monotonic plastic zone size (r,) obtained by calculation. The observed depths below the fracture surface bpeak) at which an increase in cr or a decrease in B was noticed, appear to be related to the conditions of the near-tip regions where the material has undergone severe fatigue damage and cyclic softening. 148 K. RAJANNA et al.

L’applicazione della diffrattometria dei raggi X per l’analisi del cedimento dei componenti meccanici

“…Mori et al [14] hanno applicato questa tecnica alla frattografia di compositi sinterizzati considerando solo situazioni statiche. Rajianna et al [15][16][17] hanno eseguito analisi frattografiche XRD su un acciaio C45 considerando differenti temperature di frattura. La maggior parte degli studi condotti si riferiscono, tuttavia, a provini standard, tipicamente provini CT. Ci sono pochi articoli che considerano l'analisi di cedimenti su elementi di macchine o componenti strutturali.…”

X‐ray fractography of a diesel engine crankshaft

“…[15], fracture surface of a dual phase stainless steel used in chemical plants is investigated. Rajanna et al 16,17 . performed XR fractographic analyses of C45 steel considering differing temperature of fracture.…”

“…[15], fracture surface of a dual phase stainless steel used in chemical plants is investigated. Rajanna et al 16,17 performed XR fractographic analyses of C45 steel considering differing temperature of fracture. Most of the research conducted in XR fractography considers standard specimens, typically compact tension ones, and is devoted to pointing out a standard XR fractography procedure and to assess potential applications and limitations of this technique for determining the characteristic fracture parameters of specimens, the solution of which is well known.…”

Duplex stainless steel fracture surface analysis using x-ray fractography

“…Variations in the residual stress (Or) and the full width at half maximum (FWHM, denoted by B) of the diffraction profile are determined as a function of the maximum stress-intensity factor (Kma x) and the depth (y) below the fracture surface. So far this technique has been employed to examine the fracture surface of materials such as high-strength aluminum alloys (Ref 2), structural steels (Ref [3][4][5], austenitic stainless steel ( Ref 6,7), and ceramics (Ref 8). This investigation examines a duplex stainless steel using this method.…”