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Investigating The Transformation Of Strain-Induced Martensite During Deformation and its Effect on the Wear Behavior of Austenitic Stainless Steel

Zare, Mahdi | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56563 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Serajzadeh, Siamak
  7. Abstract:
  8. In austenitic stainless steel types 304 and 316, due to the instability of the austenite phase, the martensite phase is formed by plastic deformation below the Md temperature. In this research, the cold rolling of 304L austenitic stainless steel and the transformation of austenite to strain-induced martensite and its effect on mechanical properties, especially wear, were studied. In this way, the samples were rolled in two modes and four passes in each mode. In the first case, the samples were cooled between each pass in water as a cooling liquid, and in the second case, the samples were cooled in each pass without using water and by air. Next, tests such as hardness measurement, uniaxial tension, optical metallography, imaging by scanning electron microscope, X-ray diffraction and pin-on-disk wear test were performed to check the mechanical and wear properties of different samples. By considering the rolled samples, it was concluded that the amount of stain-induced martensite was higher in the water-cooled rolled samples than in the air-cooled rolled samples. Also, with the increase of strain, α' martensite increased in both series of samples. Because of this, the mechanical properties including the wear properties of the samples improved. Also, to investigate the amount of martensite formed in different rolling conditions, the Olson-Cohen kinetic model was used and to estimate the temperature increase during cold rolling, simulation using Abaqus software was used. The results of Olson-Cohen showed that with the increase in the strain rate, the coefficient α, which shows the rate of formation of shear bands, increased, but the coefficient β, which shows the possibility shear bands intersection, due to the increase in temperature because of adiabatic conditions in higher strain rates, decrease and consiquently the process of forming martensite slows down. Also, the Abaqus simulation shows an increase in temperature by increasing the number of passes from 39◦C for one pass to 43◦C for four cold rolling passes of air-cooled samples and an average temperature of 33◦C for water-cooled samples
  9. Keywords:
  10. 304 Austenitic Stainless Steel ; Wear Properties ; Martensite ; ABAQUS Software ; Martensitic Phase Transformation ; Wear Behavior

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