equal channel angular pressing (rus. равноканальное угловое прессование abbr., РКУП) — method of severe plastic deformation in which the billet is successively forced through several channels of equal cross-section intersecting at an angle.

Description

This method is used to obtain high-density nanostructured materials with high morphological homogeneity of the grain from massive plastically deformable billets. The shear deformation of the specimen occurs when crossing the area of contact between the channels (see Fig. 1). The repeated iterations of the ECAP procedure produce a systematic increase of deformation, leading to a successive decrease in grain size by means of forming a grid of first low-angle and then high-angle boundaries. This feature enables the severe plastic deformation of not only plastic, but also difficult-to-deform metals and alloys. The channels intersection angle of the mould is of great importance. ECAP can be used to control the crystallographic texture of structural bulk nanostructured materials.

Reduction of the processed metals and alloys to the submicron grain size can lead to significant improvements in their mechanical properties, in particular increasing the materials' tensile strength and yield strength, as well as giving them superplastic capability, which is of great interest to the modern aerospace industry.

Illustrations

Fig. 1. Schematic representation of ECAP modifications: A — template orientation does not change

Fig. 1. Schematic representation of ECAP modifications: A — template orientation does not change after each run; B — after each new run, the template makes a 90° turn around its longitudinal axis; C — after each new run, the template makes a 180° turn around its longitudinal axis.

Fig. 2. Schematic representation of the change in microstructure of an aluminum sheet (a) after two
Fig. 2. Schematic representation of the change in microstructure of an aluminum sheet (a) after two (b) and four (с) repetitions of equal channel angular extrusion.

Author

  • Petrova Nyurguyana D.

Sources

  1. Valiev R.Z., Islamgaliev R.K., Alexandrov I.V., Bulk Nanostructured Materials from Severe Plastic Deformation. — Mat. Sci. 2000, pp. 183 p.
  2. Valiev R.Z. Development of equal-channel angular pressing to produce ultrafine-grained metals and alloys (in Russian). // Metals. 2004. №1. 15–22 pp.
  3. Gorynin V.I. Researches and developments of FSUE CRISM "Prometey" in the field of structural nanomaterials (in Russian). Part 2, 01.09.2008 // IA Neftegaz.RU, 2008–2009. — http://popnano.ru/analit/index.php?task=view&id=295 (reference date: 31.07.2010).
  4. The development of SPD methods (in Russian). // Information portal on nanoSPD-materials. — NanoSPD, 2007– 2009. — http://nanospd.ru/ifpm_nay_napravl_1.html (reference date: 31.07.2010).

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