Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

Pater, Z.; Tomczak, J.; Bulzak, Tomasz; Bartnicki, J.; Tofil, Arkadiusz

doi:10.3390/ma12142287

Cited by 27 publications

(19 citation statements)

References 34 publications

(31 reference statements)

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“…The research in this area is globally active and ongoing. Pater et al [3] compared nine fracture criteria to find the one most suitable for the prediction of central crack formation. Yang et al [4] studied central crack formation on a microstructural scale and revealed the ductile fracture mechanism of steels at high temperature.…”

Section: Introductionmentioning

confidence: 99%

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

et al. 2020

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Central cracking in cross-wedge-rolled workpieces results in high wastage and economic loss. Recent cross-wedge rolling tests on two batches of steel showed that one batch formed central cracks, while the other was crack-free. The batches were both nominally of the same chemical composition and thermomechanical treatment history. In addition, both batches had passed all the standard quality assessments set for conventional forging processes. It was suspected that the different cracking behaviours were due to differences in microstructure between the two as-received steel billets, and the material in cross-wedge rolling (CWR) was more sensitive to the initial microstructure compared with other forging processes due to its specific loading condition including ostensibly compression and large plastic strain. Nevertheless, no previous study of this important problem could be identified. The aim of this study is, therefore, to identify the key microstructural features determining the central crack formation behaviour in CWR. The hot workability of the as-received billets was studied under uniaxial tensile conditions using a Gleeble 3800 test machine. Scanning electron microscope with energy-dispersive X-ray spectroscopy and electron backscatter diffraction was applied to characterise, quantitatively analyse, and compare the chemical composition, phase, grain, and inclusions in these two billets, both at room temperature and also at the CWR temperature (1080°C). Non-metallic inclusions (oxides, sulphides, and silicates) in the billets were determined to be the main cause of the reported central cracking problem. The ductility of the steels at both room and elevated temperatures deteriorated markedly in the presence of the large volumes of inclusions. Grain boundary embrittlement occurred at the CWR temperature due to the aggregation of inclusions along the grain boundaries. It is suggested that a standard on specifying the inclusion quantity and size in CWR billets be established to produce crack-free products.

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Section: Introductionmentioning

confidence: 99%

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

et al. 2020

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“…This can be assumed upon observing the distribution of the y damage function determined on the basis of the normalized Cockcroft-Latham criterion, shown in Figure 12 and 13. The maximum values of this parameter are lower than 0.8, while material cracking occurs during cross and wedge rolling, with those values c.a.. three times higher [7]. The beneficial effect does not depend on the wall thickness.…”

Section: Resultsmentioning

confidence: 81%

Numerical Analysis of the Cross-Wedge of a Hollow Rail Axle

Pater¹,

Lis²,

Walczuk-Gągała³

2020

Adv. Sci. Technol. Res. J.

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The article presents an innovative method of manufacturing hollow rail axles using three combined wedge rolls. The proposed solution was evaluated using numerical simulation. Two cases of forming, differing in the wall thickness of the billet, were analysed. The geometry of the formed axles, distributions of the effective strain, temperature and damage function were presented. Moreover, the changes to the forces and torques acting on each roll were presented.

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“…Forming, the program used in the simulation. This model was successfully used multiple times by the authors in simulations of the rolling processes [50,51].…”

Section: Numerical Analysismentioning

confidence: 99%

Rotational Compression of Cylindrical Specimen As a New Calibrating Test for Damage Criteria

et al. 2020

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The subject-matter of the article is the ductile fracture of materials—A phenomenon occurring in numerous metal forming processes. In order to prognosticate the possibility of a fracture, damage criteria are employed. Their effectiveness, however, depends on the accurate determination of the critical values of damage. These values are obtained through calibrating tests, where the stress state has to be as similar to the actual process as possible. The currently employed calibrating tests do not enable one to determine the limit values of the damage function when the Mannesmann effect occurs. Therefore it was not possible to effectively prognosticate the material fracture in the processes of cross- and skew-rolling. A new calibrating test, based on rotational compression of a cylindrical sample, in which the fractures are caused by the Mannesmann effect, was developed at the Lublin University of Technology. This test was discussed in the article, with a particular focus on the stress and strain state in the sample. A practical use of the test was presented on the example of C45 grade steel, formed in the temperature equal 1150 °C. In the research ten material damage criteria were adopted.

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Prediction of Crack Formation for Cross Wedge Rolling of Harrow Tooth Preform

Cited by 27 publications

References 34 publications

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

Microstructural effects on central crack formation in hot cross-wedge-rolled high-strength steel parts

Numerical Analysis of the Cross-Wedge of a Hollow Rail Axle

Rotational Compression of Cylindrical Specimen As a New Calibrating Test for Damage Criteria

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