1. Fe 3 Al 1/4 cycle CGP at RT R. Łyszkowski, J. Bystrzycki, D. Kurowski, Z. Bojar, A. Fraczkiewicz 1, Z. Pakieła 2 Faculty of Advanced Technology and Chemistry Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland 1 – Ecole Nationale Superieure Mines, Saint-Etien, France 2 – Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw, Poland GRAIN REFINEMENT IN CONSTRAINED GROOVE PRESSING OF METALS AND ALLOYS September 14-18 2009, Warsaw University of Technology, Poland Introduction Severe plastic deformation (SPD) is one of the most effective methods for producing nanocrystalline (grain size < 100 nm) or ultrafine-grained (100 nm < grain size < 1000 nm) metals and alloys. There are several SPD techniques to synthesize bulk nano- or ultrafine metals (alloys), including equal channel angular pressing (ECAP) and high-pressure torsion (HPT). However, both of these techniques are discontinuous processes and can be applied to fabrication of samples up to certain sizes. Recently, it has been shown the effectiveness of constrained groove pressing or rolling (CGP/R) in reducing the grain size from tens of micrometers to submicrometers in several materials. In our work the applicability of CGP for grain refinement and improvement in mechanical properties of different metals and alloys was studied. The influence of repeated CGP (different number of passes) on microstructure and mechanical properties was investigated. Changes in mechanical properties were measured by tensile test and then related to microstructure development. Conclusions Severe plastic deformation by constrained groove pressing (CGP) of different metals and alloys at room and elevated temperature was investigated. In the CGP method material is subjected to the repetitive shear deformation under the plane strain deformation condition. The most pronounced yield point and tensile strength were measured after 2 cycles for iron. The results of mechanical tests revealed the mechanical superiority of iron sample fabricated by the present CGP method. Financial support from Polish Committee for Scientific Research is gratefully acknowledged. (Grant no: R 15 0010 06/2009 and 344/1/R/T02/2008/IT1) Experimental Processing: Both Fe(Al) and Fe 3 Al alloys were prepared by induction melting in an argon atmosphere and then homogenized at 1100  C for 10h, hot forged or rolled at 1100  C) and recrystallized. The initials Al and Fe sheets were only recrystallized. Severe plastic deformation: Constrained Groove Pressing (CGP) at RT for Al and Fe and at 700  C for Fe(Al) and Fe 3 Al alloys. Investigations: light microscopy (SEM), tensile tests and hardness Diagram showing following steps in CGP process. Results of investigation of mechanical properties, before and after CGP proces. G B P z y x TEM EBSD ttt t t Undeformed region Bending and stretching region Pure shear region Upper die Downer die t = 3 mm Non deformation   0.6   1.2 MaterialState Yield point R e [MPa] Tensile strenght R m [MPa] Tensile cracking R c [MPa] Fe(Al) Initial 490510 Deformed 850836 Fe 3 Al Initial 173198145 Deformed 261266249 Fe Initial 130242135 Deformed 690760380 Al Initial 10811742 Deformed 11712966 Scheme showing regions of different deformation modes in the workpiece. dr inż. Radosław Łyszkowski Faculty of Advanced Technology and Chemistry Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland Tel. +48 22 683 7628, fax. +48 22 683 9445 E-mail: rlyszkowski@wat.edu.pl Fe(Al) Fe 3 Al Al Fe Microstructures of specimens deformed by CGP Microhardness HV0.1 Fe 3 Al 1 cycle CGP at 700  C Fe 2 cycles CGP at RT Fracture surface of investigated alloys Fe(Al)/Fe 3 Al Fe Fe 3 Al Al Fe 3 Al / Fe(Al)