A model of extrusions and intrusions in fatigued metals II. Surface roughening by random irreversible slip

Differt, K.; Esmann, U.; Mughrabi, H.

doi:10.1080/01418618608242897

Cited by 118 publications

(60 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[10], it should be noted that the constant 6 under the square root has now been replaced by 4, and h now represents the atomic plane spacing. [28,29] Then, from experiment, an average value for the local shear strain amplitude c pl,PSB and the number of cycles N until softening is complete can be determined. Thus, the cyclic slip irreversibility p in the PSBs can be estimated.…”

Section: B Fatigued Precipitation-hardened Alloysmentioning

confidence: 99%

“…It is expedient to characterize the degree of cyclic slip irreversibility by some quantity. Here, the cyclic slip irreversibility p will be defined, as in earlier work, [25][26][27][28][29][30][31][32][33][34][35] as the fraction of plastic shear deformation that is irreversible in a microstructural sense: p ¼ irreversible plastic shear strain cumulative total plastic shear strain ½1…”

Section: Origin and Definition Of Cyclic Slip Irreversibilitiesmentioning

confidence: 99%

See 1 more Smart Citation

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

Mughrabi

2009

Metall Mater Trans B

176

View full text Add to dashboard Cite

In this article, the physical origin of fatigue crack initiation in ductile metals is discussed from a historical perspective. The main focus is to assess those cyclic slip irreversibilities in a microstructural sense that occur not only at the surface but also in the bulk at the dislocation scale and to show how they contribute to surface fatigue damage. The evolution of early fatigue damage, as evidenced experimentally in the last decades, is reviewed. The phenomenon of cyclic strain localization in persistent slip bands (PSBs) and models of the formation of extrusions, intrusions, and microcracks are discussed in detail. The predictions of these models are compared with experimental evidence obtained on mono-and polycrystalline face-centered-cubic (fcc) metals. In addition, examples of the evolution of fatigue damage in selected fcc solid solution alloys and precipitation-hardened alloys and in body-centered-cubic (bcc) metals are analyzed. Where possible, the cyclic slip irreversibilities p, defined as the fraction of plastic shear strain that is microstructurally irreversible, have been estimated quantitatively. Broadly speaking, p has been found to vary over orders of magnitude (0 < p < 1), being almost negligible at low loading amplitudes (high fatigue lives) and substantial at larger loading amplitudes (low fatigue lives). and Dean of the School of Engineering. Since 2002, Hael Mughrabi has been formally retired but is still active in various forms in research and in committee work.Hael Mughrabi has published almost 300 papers and book chapters and has been editor or co-editor of several books and conference proceedings, mainly in the fields of crystal plasticity, materials characterization, metal fatigue, high-temperature mechanical properties of nickel-base superalloys, and modeling of mechanical behavior. He has been active in the organization and chairing of many international conferences and has frequently been invited as a plenary or keynote speaker. Hael Mughrabi has been a member of TMS for 25 years and of a number of other professional societies, including the German Materials Society (Deutsche Gesellschaft fu¨r Materialkunde (DGM)). He has been a member of the Board of Directors of DGM and Chairman of the DGM Awards Committee PKII and has been elected an Honorary Member of DGM. Hael Mughrabi is the holder of an Honorary Doctoral degree from the Ruhr University Bochum and the recipient of several national and international awards, including the highest award of DGM, the Heyn-Denkmu¨nze.

show abstract

Section: B Fatigued Precipitation-hardened Alloysmentioning

confidence: 99%

Section: Origin and Definition Of Cyclic Slip Irreversibilitiesmentioning

confidence: 99%

Cyclic Slip Irreversibilities and the Evolution of Fatigue Damage

Mughrabi

2009

Metall Mater Trans B

176

View full text Add to dashboard Cite

show abstract

“…4 represents interaction energy between the PSB and GB, where E γ GB is the transmission energy for a dislocation to penetrate through a specific grain boundary type, as detailed in reference [47]. Also, n ext is the size of the extrusion or step that forms at the grain boundary, based on an expression of the form given by Mughrabi et al [48,49], such that…”

Section: Design For Fatigue Enhancementmentioning

confidence: 99%

Tailoring the Properties of a Ni-Based Superalloy via Modification of the Forging Process: an ICME Approach to Fatigue Performance

Detrois

Rotella

Hardy

et al. 2017

Integr Mater Manuf Innov

View full text Add to dashboard Cite

Traditionally, material design and property modifications are usually associated with compositional changes. Yet, subtle changes in the manufacturing process parameters can also have a dramatic effect on the resulting material properties. In this work, an integrated computational materials engineering (ICME) framework is adopted to tailor the fatigue performance of a Ni-based superalloy, RR1000. An existing fatigue model is used to identify microstructural features that promote enhanced fatigue life, namely a uniform, fine grain size distribution, random orientation, a distinct grain boundary distribution (specifically high twin boundary density and limited low-angle grain boundaries). A deformation mechanism map and process models for grain boundary engineering of RR1000 are used to identify the optimal thermo-mechanical processing parameters to realize these desirable microstructural features. For validation, small-scale forgings of RR1000 were produced and heat-treated to attain fine grain and coarse grain microstructures that represent the conventionally processed and grain boundary engineered (GBE) conditions, respectively. For each of the four microstructural variants of RR1000, the twin density and grain size were characterized and were in agreement with the desired microstructural attributes. In order to validate the deformation mechanisms and fatigue behavior of the material, high-resolution digital image correlation was performed to generate strain maps relative to the microstructural features. The high density of twin boundaries was confirmed to inhibit the length of slip bands, which is directly attributed to extended fatigue life. Thus, this study demonstrated the successful role of models, both process and performance, in the design and manufacture of Ni-based superalloy disk forgings.

show abstract

“…All physically based models [3,[24][25][26][27][28][29] are based on the dislocation structure of PSBs and the neighbor matrix and on the interactions between mobile dislocations leading to the formation of point defects or dipoles. Some models [3,[24][25][26] emphasize the role of extrusions in the formation of stage I cracks, others [27][28][29] consider intrusions to be the principal source of stage I cracks. Therefore, the details of the surface relief and simultaneously the dislocation arrangement appertaining to this surface relief are of substantial interest in checking the validity of these models.…”

mentioning

confidence: 99%