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

Minoru Umemoto; Yoshikazu Todaka; Jun Sasaki; Innocent Shuro

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

Paper Titles

Mechanical Behavior and Stress-Induced Martensitic Transformation in Nanocrystalline Ti_49.4Ni_50.6 Alloy
p.470

Effect of Nanocrystalline Structure and Polygonized Dislocation Substructure on Ti-Ni Martensite Lattice Parameters and Transformation Lattice Strain
p.475

Effect of Processing Temperature on Microstructure Development during ECAP of Al-Mg-Sc Alloy
p.481

Effects of Equal-Channel Angular Pressing on the Anisotropy of Ultrafine Copper and Titanium
p.487

Strain Gradient Hardening and Pressure Induced Phase Transformation of Metals by HPT
p.493

Effect of Pre-Aging on the Microstructure and Strength of Supersaturated AlZnMg Alloys Processed by ECAP
p.501

Nanostructured Shape Memory TiNi Alloy Processed by Severe Electroplastic Deformation
p.507

Texture Gradient in a Single Pass ECAPed Pure Mg by Neutron Radiation
p.513

Life Time Predictions through X-Ray Defect Analysis of MEMS Devices
p.518

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

Abstract:

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.