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Full-Text Articles in Engineering Science and Materials

Doppler Broadening Analysis Of Steel Specimens Using Accelerator Based In Situ Pair Production, V. Makarashvili, Douglas P. Wells, Ajit K. Roy Aug 2009

Doppler Broadening Analysis Of Steel Specimens Using Accelerator Based In Situ Pair Production, V. Makarashvili, Douglas P. Wells, Ajit K. Roy

Mechanical Engineering Faculty Publications

Positron Annihilation Spectroscopy (PAS) techniques can be utilized as a sensitive probe of defects in materials. Studying these microscopic defects is very important for a number of industries in order to predict material failure or structural integrity. We have been developing gamma‐induced pair‐production techniques to produce positrons in thick samples ( ∼4–40 g/cm2, or ∼0.5–5 cm in steel). These techniques are called ‘Accelerator‐based Gamma‐induced Positron Annihilation Spectroscopy’ (AG‐PAS). We have begun testing the capabilities of this technique for imaging of defect densities in thick structural materials. As a first step, a linear ...


The Effect Of Silicon Content On Impact Toughness Of T91 Grade Steels, Ajit K. Roy, Pankaj Kumar, Debajyoti Maitra Mar 2009

The Effect Of Silicon Content On Impact Toughness Of T91 Grade Steels, Ajit K. Roy, Pankaj Kumar, Debajyoti Maitra

Mechanical Engineering Faculty Publications

The impact resistance of silicon (Si)-containing modified 9Cr-1Mo steels has been investigated within a temperature regime of -40 to 440°C using the Charpy method. The results indicate that the energies absorbed in fracturing the tested specimens were substantially lower at temperatures of -40, 25, and 75°C compared to those at elevated temperatures. Lower impact energies and higher ductile-to-brittle-transition-temperatures (DBTTs) were observed with the steels containing 1.5 and 1.9 wt.% Si. The steels containing higher Si levels exhibited both ductile and brittle failures at elevated temperatures. However, at lower temperatures, brittle failures characterized by cleavage and ...