Title:        Candidate
First Name:   Sitdikov
Last Name:    Vil
Sex:          male
Affiliation:  Ufa State Aviation Technical University
Adress:       12 K. Marx
City:         Ufa
Postal Code:  450000
Country:      Russia
Phone:        +7(347) 273 7977
Email:        svil@mail.rb.ru
Abstract:     Evolution of Residual Stresses, Crystallographic Texture and Microhardness in Metals under Severe Plastic Deformation

*I. Alexandrov, **J. Bonarski, ***A. Korshunov, **L. Tarkowski and *V. Sitdikov
*Ufa State Aviation Technical University, 450000, 12 K. Marx, Ufa, Russia
**Institute of Metallurgy and Materials Science, 25 Reymonta, 30-059 Krakow, Poland
*** Russian Federal Nuclear center VNIIEF, 607190, 37 Mira Ave., Sarov, Russia

At the present time severe plastic deformation (SPD) technique is one of the main techniques for processing bulk nanostructured materials [1]. Structure formed as a result of SPD is characterized by an average grain size of several tens of nanometers and an extremely non-equilibrium state of their boundaries. As a result bulk nanostructured materials obtained after SPD demonstrate SPD paradox (simultaneous manifestation of high strength and ductility), absence of the deformation hardening, low-temperature or high-rate superplasticity [1, 2]. 
The report presents the results of X-ray experimental studies of the evolution of residual stresses, crystallographic texture, microhardness in the bulk of Cu and Ti billets subjected to equal-channel angular pressing (ECAP). Investigations were conducted on different points of the central vertical section of billets which passed through the die channels during the 1st and subsequent (up to the 4th) ECAP passes (route ВС). The temperature for ECAP was chosen as room for Cu billets and 450 °С for Ti billets. 
Computer simulation within the frame of a visco-plastic self-consistent model was used to analyze texture formation processes during ECAP. Possibility for activation of crystallographic slip and twinning typical of the mentioned metals was considered. 
Regularities of formation of residual stress fields, preferred orientations and microhardness were stated as a result of the conducted investigations. Conclusions on correlation between them and on the influence of the crystalline lattice type and number of ECAP passes on the level and homogeneity of distribution of the mentioned features in the bulk of deformed billets were made.

[1]   R.Z. Valiev, R.K. Islamgaliev, I.V. Alexandrov, Progress Mater. Sci. 45 (2000) 103-189.
[2]   R. Z. Valiev, I. V. Alexandrov, Y. T. Zhu, T. C. Lowe, J. Mater. Res. 17 (2002) 5-8.

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