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| Kvačkaj T., Molnárová M., Mišičko R.., Fujda M. |
| INFLUENCE OF TERMAL CONDITIONS ON FORMATION OF DUAL PHASE STRUCTURES |
Abstract
Ultrafine - grained materials represent a new generation of advanced materials exhibiting unique and technologically attractive properties. The paper analyses present issue, focusing on the formation and classification of nanomaterials as well as on their mechanism of plastic deformation. Validity diversion of Hall – Petch relationship has been defined for nanostructured materials. The Hall – Petch deviation is made by different plastic deformation mechanisms for nanostructured materials and conventional coarse – grained metals.
Today there are more than 30 different processes for manufacture of nanostructured materials, some of them include methods, which are based on severe plastic deformation (SPD). The ECAP, which is one of them is nowadays one of the most used and promising technology for processing ultrafine – grained metals. The paper deal with influence of channels angle ECAP die on state of stress, the state of strain and evolution of temperature, realized by mathematical simulation. Simulations were realized for IF steel in software product DEFORM based on FEM. From mathematical simulation is resulting, that the most values of deformation strength of temperature have been achieved when the angle of channels was 90°. When the value of the angle of channel is increased, the value of effective strain and temperature are decreased. Based on the mathematical simulation, the concentration of the stress to transitional area of punch has been defined. This fact was later supported by the experiment, when during ECAP processing a superficial damage at the tension strain ?3,skut = 2750 MPa has occurred.
The conclusion of this paper deals with the influence of SPD technology on mechanical properties of some materials (composite Al-Al4C3, Cu, Fe-ARMCO, IF-steel). The diameter of grain size before ECAP processing was in interval 1- 50 ?m. The diameter of grain size after ECAP processing was reduced below 600nm.
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| Keywords: Controlled rolling|controlled cooling|structure|ferrite|martensite|pearlite| |
| No 3 (2007), p. 320-328 |
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| Fröhlichová M., Fröhlich L., Borovský T. |
| ANALYSE OF TITANIUM EFFECT ON THERMAL STATE IN THE HEARTH OF BF |
| Keywords: Blast furnace|hearth|refractory wear|titanium bearing raw material|titanium carbonitrides|protective layer| |
| No 3 (2007), p. 353-359 |
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| Brehuv J., Magula R. |
| KNOWN AND UNKNOWN MINING-PROCESSING ACTIVITIES OF RISTOCRATIC FAMILY „DE SOÓSO“ |
| Keywords: |
| No 3 (2007), p. 460-464 |
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