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Deformation Behavior and Effect of Strain Path on Strain-Induced Martensite Transformation in Austenitic Stainless Steel

Lotfinia, Mahshad | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53476 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Serajzadeh, Siamak
  7. Abstract:
  8. In some of the austenitic stainless steels, the strain-induced martensite transformation occurs during the deformation processing owing to instability of austenite phase at low temperatures. In this study, formation of strain-induced martensite as well as the impact of strain path on the rate of martensite transformation in 316L austenitic stainless steel were investigated. At first, the multi-pass cold rolling experiments at room temperature and -8 ℃ were conducted in which both direct and reverse rolling layouts were taken into account. Then, as the third path, the uni-axial tensile loading with an appropriate strain rate was considered. After that, in order to examine the mechanical and corrosion behaviors of the deformed samples, different tests including the Vickers hardness test, tensile test, optic metallography analysis, scanning electron microscopy, x-ray diffraction, wear test, and linear polarization were carried out. The results demonstrated that an optimum mechanical and corrosion properties could be achieved employing an appropriate rolling program. In the second part of this study, the work-roll deflection during multi-pass rolling operations was predicted employing a combined model using finite element method, artificial neural network (ANN) and finite difference scheme. The ANN modeling was utilized for calculating the flow stress of the steel being rolled while the mean pressure was calculated based on cold rolling theories coupled with the finite difference approach. Finally, the work-roll deflection was determined by means of the predicted mean roll pressure and finite element formulation. It was found that that an increase in the number of passes as well as reducing rolling temperature lead to an increase in work-roll the deflection
  9. Keywords:
  10. Austenitic Stainless Steel ; Microstructure ; Deflection ; Strain Path ; Martensitic Transformation ; Austenite Transformation ; Tensile Test

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