- Post Doctoral
MIT Unit Affiliation:
- Materials Science and Engineering
- Mechanical Engineering
Post Doc Sponsor / Advisor:
Date PhD Completed:
Top 3 Areas of Expertise:
As a Roberto Rocca Fellow, I am performing my postdoctoral research in the Department of Materials Science and Engineering (DMSE) at MIT. I was awarded the PhD degree with the highest institute honors from Polytechnic University of Milan, Department of Mechanical Engineering. Being exposed to both realms of Mechanical Engineering and Materials Science, I seek to address challenges at the interface of mechanic and materials with a particular emphasis on processing-structure-property relationship in nanocrystalline metals.
Expected End Date of Post Doctoral Position:
From nanostructured powders to bulk nanocrystalline pieces: kinetic rather than thermal energy
Most material failures, including fatigue fracture, fretting fatigue, wear and corrosion are very sensitive to the structure and properties of a material’s surface, and many of these properties are known to improve in fine grained and nanocrystalline (NC) materials. As a result, methods to achieve a nanocrystalline surface layer over bulk material are of broad interest, especially since surface nanocrystallization processing techniques may bypass the difficulties of synthesizing bulk NC components and yet exploit the advantages of NC materials in service.
The focus of my PhD thesis was to explore severe plastic deformation, severe shot peening in particular, to generate nanostructured surface layers on high strength low alloy steel. Different experiments such as scanning and transmission electron microscopy observations, X-ray diffraction, residual stress measurements and mechanical fatigue tests have been conducted to systematically study the degree and the mechanism of grain refinement during severe plastic deformation, and to characterize the properties of nanostructured surface layers. A model linking finite element simulation of severe peening to the dislocation density evolution has been developed to predict the resultant grain/cell size gradient in the surface layers. Improved fatigue properties and high diffusivity were found in the nanostructured surface layers. These advantages led to 50% duration reduction of a high temperature thermochemical surface treatment in the manufacturing cycle without compromising the resultant properties.
Top 5 Awards and honors (name of award, date received):
5 Recent Papers:
SM Hassani-Gangaraj, KS Cho, H-JL Voigt, M Guagliano, CA Schuh. (2015), "Experimental assessment and simulation of surface nanocrystallization by severe shot peening" Acta Materialia (97) 105-115.
SM Hassani-Gangaraj, A. Moridi, M Guagliano, A Ghidini, M Boniardi. (2014). "The effect of nitriding, severe shot peening and their combination on the fatigue behavior and micro-structure of a low-alloy steel," International Journal of Fatigue (62) 67–76.
A. Moridi, SM Hassani-Gangaraj, M Guagliano, M Dao. (2014), "Cold spray coating: a review of the material systems and future perspectives," Surface Engineering (30) 369-395.
SM Hassani-Gangaraj, A. Moridi, M Guagliano, A Ghidini. (2014), "Nitriding duration reduction without sacrificing mechanical characteristics and fatigue behavior: The beneficial effect of surface nano-crystallization by prior severe shot peening," Materials & Design (55) 492-498.
SM Hassani-Gangaraj, A. Moridi, M Guagliano, (2015) "A critical review of corrosion protection by cold spray coatings," Surface Engineering, in press.