Strain Gradient Hardening and Pressure Induced Phase Transformation of Metals by HPT

Abstract:

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Two unique characteristics of HPT as a SPD process, namely deformation with strain gradient and deformation under high pressure, were investigated. The effect of strain gradient was examined using low carbon steel. HPTed samples showed hardening at the center of the specimen where shear strain is principally zero and saturation hardness was higher than those without strain gradient such as ECAP or ARB. HPT experiments using specimen with different radial strain gradient in one sample also showed strain gradient hardening. The effect of high pressure during HPT was examined using pure Ti which transformed from α phase to ω phase when HPTed at high pressure. The volume fraction of ω phase increases with strain and with decreasing oxygen content. The ω phase is metastable at ambient conditions and it transforms back to α phase during heating.

Info:

Periodical:

Materials Science Forum (Volumes 584-586)

Edited by:

Yuri Estrin and Hans Jürgen Maier

Pages:

493-500

DOI:

10.4028/www.scientific.net/MSF.584-586.493

Citation:

M. Umemoto et al., "Strain Gradient Hardening and Pressure Induced Phase Transformation of Metals by HPT", Materials Science Forum, Vols. 584-586, pp. 493-500, 2008

Online since:

June 2008

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Price:

$35.00

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