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Production of Nanostructured Composite Sheets of AA1100/St37 Using ARB Technique and Evaluation of Heat Treatment Effect on Grains Structure

Vakili, Hossein | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40584 (07)
  4. University: Sharif University of Technology
  5. Department: Materials science and Engineering
  6. Advisor(s): Asgari, Sirous
  7. Abstract:
  8. In present work, nanostructured multilayer composites produced from AA1100 and St37 alloys and mechanical properties of resulted samples characterized using tension and micro hardness tests. Also dispersion pattern of second phase in matrix studied via optical microscopy. Thickness of second phase layers showed a little reduction after 2 ARB cycles; but their length decrease gradually. With increasing number of ARB cycles up to 6 cycles, sample's tensile strength first decrease rapidly and after that increased, but never reached initial value. In order to evaluation of heat treatment effects on samples grain structure, samples heat treated and tensile test carried on them. Annealing at 300 and 30 minute showed the best combination of strength and elongation and higher temperatures lead to decrease of both properties together. SEM studies near the heat treated interface confirmed the occurrence of diffusion process. In this composite, rate of changing in mechanical properties versus temperature, is significantly less than pure aluminum which processed via ARB. Annealing in 400 cause to some change in crystal structure of material which may probably due to recrystallization texture effects. In order to estimate the amount of tensile strength in unpreheated rolling condition, a formulation proposed which prediction had good confirm in a wide range of strain
  9. Keywords:
  10. Accumulative Roll Bonding (ARB) ; Microstructural Changes ; Transmission Electron Microscope ; Aluminum Alloy 1100 ; Ultra-Fine Grain Materials

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