Deformation homogeneity, mechanical behaviour and strain hardening characteristics of titanium severe plastically deformed by cyclic channel die compression method

作者：Kumar S S Satheesh^*; Priyasudha K; Rao M Sudhakara; Raghu T

来源：Materials and Design, 2016, 101: 117-129.

DOI：10.1016/j.matdes.2016.04.004

• Cyclic channel die compression
• Ultrafine titanium
• Strain hardening
• Deformation homogeneity

Pure titaniumis severe plastically deformed up to epsilon = 9.6 through four cycles of cyclic channel die compression at warm temperature (500 degrees C) to obtain ultrafine grained structure (0.7-0.3 mu m). The evolution of microstructural homogeneity with strain is investigated by examining the macro/micro structures coupled with an extensive microhardness profile analysis at different cumulative plastic strain (epsilon = 2.4, 4.8, 7.2, 9.6). Additionally, the degree of deformation inhomogeneity is evaluated quantitatively by employing appropriate statistical parameter, which indicated improvement in structural homogeneity with increased straining. Mechanical behaviour investigated by room temperature tensile tests indicated remarkable improvement in strengths with negligible strain hardening ability and reasonable ductility. In annealed condition, the flow curve in the uniform plastic deformation regime is described by Ludwik relationship; while the flow curves obey Voce behaviour in severely deformed condition signifying stress saturation at large strain. The analysis of strain hardening characteristics by Kocks-Mecking plots exhibited three stage behaviour in annealed titanium which is replaced by a single stage behaviour in ultrafine grained titanium substantiating the dominance of slip mediated mechanisms during plastic deformation. Towards the end, the observation of early tensile instability and low tensile strains in severely deformed titanium is analyzed by employing ConsidSre criterion.

• 出版日期2016-7-5