Influence of Severe Plastic Deformation Induced by HE and ECAP on the Thermo-Physical Properties of Metals

2015 ◽  
Vol 641 ◽  
pp. 278-285
Author(s):  
Jacek Skiba ◽  
Adam Dominiak ◽  
Tomasz S. Wiśniewski ◽  
Wacek Pachla ◽  
Mariusz Kulczyk ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Physical Properties ◽  
Specific Heat ◽  
Pure Copper ◽  
Deformation Method ◽  
Fine Grained ◽  
Angular Pressing ◽  
Fine Grained Structure ◽  
Thermo Physical Properties

The study is aimed at comparing the changes which occur in the microstructure and thermo-physical properties of pure copper (99.9%) and when copper alloyed with chromium and zirconium subjected to severe plastic deformation (SPD). The plastic deformation techniques employed were hydrostatic extrusion (HE), equal channel angular pressing (ECAP), and a combination of these two processes. The materials thus obtained had an ultra-fine-grained structure with the thermo-physical properties differing from those of the untreated materials. It appeared that there is a correlation between the deformation method employed and the thermo-physical properties of the materials, such as diffusivity and specific heat.

Role of Strain Gradient and Dynamic Transformation on the Formation of Nanocrystalline Structure Produced by Severe Plastic Deformation

2007 ◽  
Vol 539-543 ◽  
pp. 2787-2792 ◽  
Author(s):  
Minoru Umemoto ◽  
Yoshikazu Todaka ◽  
Jin Guo Li ◽  
Koichi Tsuchiya
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Strain Gradient ◽  
High Pressure Torsion ◽  
Large Strain ◽  
Nanocrystalline Structure ◽  
Angular Pressing ◽  
Dynamic Transformation ◽  
Fine Grained Structure

Formation of nanocrystalline structure by severe plastic deformation has studied extensively. Although ultra fine grained structure (grain size larger than 100 nm) had been obtained in many processes such as heavy cold rolling, equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), the formation of nano grained structure (< 100 nm) is limited to processes such as ball milling, shot peening or drilling. In the present study, high pressure torsion (HPT) deformation and drilling were carried out to understand the conditions necessary to obtain nano grained structure in steels. The results of HPT experiments in pure Fe showed that HPT has superior ability of strengthening and grain refinement probably due to a strain gradient but the saturation of grain refinement occurs before reaching nano grained structure. Drilling experiments in high carbon martensitic steel revelaed that nano grained ferrite forms at the drilled hole surface only when the transformation from ferrite to austenite takes place during drilling. Considering various other processes by which nano grained ferrite was produced, it is proposed that heavy strains with large strain gradients together with dynamic transformation are necessary to reach nano grained ferrite structure.

Development of Ultra-Fine Grained Structure in an Al-5.4%Mg-0.5%Mn Alloy Processed by ECAP

2010 ◽  
Vol 667-669 ◽  
pp. 487-492
Author(s):  
Alla Kipelova ◽  
Ilya Nikulin ◽  
Sergey Malopheyev ◽  
Rustam Kaibyshev
Keyword(s):  
Plastic Deformation ◽  
Structure Formation ◽  
Equal Channel Angular Pressing ◽  
Microstructural Evolution ◽  
Coarse Grained ◽  
High Angle ◽  
Fine Grained ◽  
Angular Pressing ◽  
Fine Grained Structure ◽  
Zr Alloy

Microstructural changes during equal channel angular pressing (ECAP) at the temperatures of 250 and 300°C to the strains ~4, ~8 and ~12 were studied in a coarse-grained Al-5.4%Mg-0.5%Mn-0.1%Zr alloy. At a strain of ~4, the microstructural evolution is mainly characterized by the development of well-defined subgrains within interiors of initial grains and the formation of fine grains along original boundaries. Further straining leads to increase in the average misorientation angle, the fraction of high-angle grain boundaries and the fraction of new grains. However, only at 300°C, the plastic deformation to a strain of ~12 leads to the formation of almost uniform submicrocrystalline (SMC) grained structure with an average crystallites size of ~ 0.5 m. At 250°C, the microstructure remains non-uniform and consists of subgrains and new recrystallized grains. The mechanism of new SMC structure formation after ECAP is discussed.

scholarly journals Effect Of Severe Plastic Deformation On Microstructure Evolution Of Pure Aluminium

2015 ◽  
Vol 60 (2) ◽  
pp. 1437-1440 ◽  
Author(s):  
B. Leszczyńska-Madej ◽  
M.W. Richert ◽  
M. Perek-Nowak
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Subgrain Size ◽  
Bulk Material ◽  
Extrusion Process ◽  
Hydrostatic Extrusion ◽  
Pure Aluminium ◽  
Fine Grained ◽  
Angular Pressing ◽  
Cumulative Strain

AbstractProcesses of severe plastic deformation (SPD) are defined as a group of metalworking techniques in which a very large plastic strain is imposed on a bulk material in order to make an ultra-fine grained metal. The present study attempts to apply Equal-Channel Angular Pressing (ECAP), Hydrostatic Extrusion (HE) and combination of ECAP and HE to 99.5% pure aluminium. ECAP process was realized at room temperature for 16 passes through route Bc using a die having an angle of 90°. Hydrostatic extrusion process was performed with cumulative strain of 2.68 to attain finally wire diameter of d = 3 mm. The microstructure of the samples was investigated by means of transmission and scanning electron microscopy. Additionally, the microhardness was measured and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns misorientation was determined. The measured grain/subgrain size show, that regardless the mode of deformation process (ECAP, HE or combination of ECAP and HE processes), grain size is maintained at a similar level – equal to d = 0.55-0.59μm. A combination of ECAP and HE has achieved better properties than either single process and show to be a promising procedure for manufacturing bulk UFG aluminium.

scholarly journals The influence of utrafine-grained state on thermo-physical properties of Zr-1 wt.% Nb and Ti-45 wt.% Nb alloys and processes of dissipation and accumulation of energy during deformation

2020 ◽  
pp. 28-35
Author(s):  
E.V. Legostaeva ◽  
◽  
Yu.P. Sharkeev ◽  
O.A. Belyavskaya ◽  
V.P. Vavilov ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Plastic Deformation ◽  
Heat Capacity ◽  
Physical Properties ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Coarse Grained ◽  
Ultrafine Grained ◽  
Substructural Hardening ◽  
Thermo Physical Properties

The results of studying the thermal conductivity and specific heat capacity of Zr-1 wt.% Nb and Ti-45 wt.% Nb in coarse-grained and ultrafine-grained states are presented. The influence of the utrafine-grained state on the thermo physical properties and the processes of dissipation and accumulation energy during deformation of the alloys are estimated. It is shown that formation of the ultrafine-grained state in the Zr-1 wt.% Nb alloy by abc -pressing and subsequent rolling leads to a decrease in its thermal conductivity and specific heat capacity by 10 and 20%, respectively, due to substructural hardening under severe plastic deformation. It is found that thermal conductivity and specific heat capacity of the ultrafine Ti-45 wt.% Nb alloy increase by 7.5 and 5%, respectively, due to dispersion hardening of the ω phase by nanoparticles and formation of a new α phase. It is established that the ultrafine-grained structure has a significant influence on the regularities of the dissipation and accumulation energy during plastic deformation, which in turn depend on their thermo-physical characteristics and on the structural and phase state.

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