Influence Of Deformation Temperature Research Articles

Influence of deformation temperature on matrix metal flow and whisker reorientation in SiCw/6061 aluminium alloy composite during compressive deformation

The matrix metal flow and whisker reorientation in directionally aligned SiCw/6061 aluminium alloy composites during compressive deformation were investigated by observing the changes in whisker orientation and specimen shape before and after compression. The results indicate that matrix metal flow and whisker reorientation during compressive deformation are dependent on deformation temperatures. The matrix metal can flow more uniformly at a higher temperature. Furthermore, the whiskers in the composites can not reorientate during compressive deformation at a lower temperature, while they can reorientate during deformation at a higher temperature in a ring specimen.

Grain Boundary Effects in Nanocrystalline Copper

The results of investigations of nanostructured copper with a mean grain size of 75 nm processed by a new method of severe plastic deformation via consolidation of ball-milled powders are given in the paper. The investigations show that the processed copper has a rather stable nanostructure during annealing and elevated strength properties. A significant influence of deformation temperature on a growth of grain size and a decrease in values of internal stresses was also revealed. Evidently, this is connected with realization of recovery processes on grain boundaries and beginning of recrystallization processes already at low homological temperatures. The obtained results show that a state of grain boundaries in nanostructured copper is a very important parameter determining properties of nanostructured materials. To explain the experimental data, the structural model of R.Z. Valiev was taken as a basis. According to this model a structure of nanostructured material consists of ultra fine elastically aligned grains characterized by high density of grain boundary dislocations and disclinations. With all that, during annealing a recovery of these defects occurs.

Hot rolling textures of f.c.c. metals—Part I. Experimental results on Al single and polycrystals

The influence of deformation temperature on the hot rolling textures of aluminium alloys has been investigated by channel die compression tests on Al1%Mg1%Mn polycrystals and oriented single crystals in the temperature range 200–400°C. Quantitative texture measurements on the polycrystalline samples demonstrate a substantial increase in the 110〈11̄2〉 “Brass” component at higher temperatures together with a small but significant amount of “near-Cube” orientations. These texture variations with temperature occur in the absence of recrystallization. The single crystal experiments show that these textures can be related to the onset of non-octahedral slip in Al and Al1%Mn under hot working conditions of high strains and medium strain rates. The “near-Cube” orientations tend to be stabilized by slip on 110 planes while the “brass” orientation undergoes a substantially reduced ε 12 (in-plane) shear. This behaviour is predicted by a rate sensitive crystal plasticity model assuming 111 and 112 slip in accordance with the experimental results at 400°C.

Annealing behaviour of dilute aluminium alloys following hot deformation

Abstract The microstructure and texture of three dilute aluminium alloys after hot deformation and annealing was assessed; In particular, the influence of deformation temperature, strain rate, and strain on the annealed texture was examined, as well as the effect of alloy composition. The microstructures of the commercially pure materials studied (Al, Al+1%Mn and Al+1%Mg) varied in the volume fraction of coarse intermetallic particles, the type of dispersoid present, and the level and type of solute in solid solution. Furthermore, the initial stages of recovery and recrystallisation were studied in detail for one of the alloys (commercially pure Al). It was found that the main recrystallisation texture component was the cube and its strength, as well as the recrystallised grain size, depended strongly on the deformation strain. The deformation strain rate and temperature, and the alloy composition also strongly influenced the grain size and cube texture strength. These results are discussed in the context...

The Influence of Deformation Temperature and Strain Rate on the Plane Strain Compression Textures of Al-1%Mn-1%Mg

The Influence of Deformation Temperature and Strain Rate on the Plane Strain Compression Textures of Al-1%Mn-1%Mg

Influence of Deformation Temperature on the Bauschinger Effect of a TRIP-Aided Dual-Phase Steel

The influence of deformation temperature on the Bauschinger effect (BE) of a high-strength TRIP-aided dual-phase (TDP) steel containing retained austenite particles of 10 vol% was investigated in a temperature range between 27 and 200°C. The BE of the TDP steel depended significantly on the deformation temperature, although such a temperature dependence did not appear in a conventional ferrite-martensite dual-phase (DP) steel. Large BE, i.e., remarkable transitional softening and subsequent permanent softening proposed by Orowan, appeared at 100 and 200°C, at which the retained austenite particles were more resistant to the strain-induced martensite transformation (SIT) than those at 27°C. The Bauschinger stress obtained at 200°C was as high as that of the DP steel. The retained austenite particles as a hard phase increased the Bauschinger stress. The SIT, however, was expected to lower the Bauschinger stress by the following reason. Expansion and shear strains resulting from the SIT reduced both internal stresses in the retained austenite islands and in the ferrite matrix.

TRIP型複合組織鋼のバウシンガー効果に及ぼす変形温度の影響

The influence of deformation temperature on the Bauschinger effect (BE) of a high-strength TRIP-aided dual-phase (TDP) steel containing retained austenite particles of 10 vol% was investigated in a temperature range between 27 and 200°C. The BE of the TDP steel depended significantly on the deformation temperature, although such a temperature dependence did not appear in a conventional ferrite-martensite dual-phase (DP) steel. Large BE, i.e., remarkable transitional softening and subsequent permanent softening proposed by Orowan, appeared at 100 and 200°C, at which the retained austenite particles were more resistant to the strain-induced martensite transformation (SIT) than those at 27°C. The Bauschinger stress obtained at 200°C was as high as that of the DP steel. The retained austenite particles as a hard phase increased the Bauschinger stress. The SIT, however, was expected to lower the Bauschinger stress by the following reason. Expansion and shear strains resulting from the SIT reduced both internal stresses in the retained austenite islands and in the ferrite matrix.

High temperature plane strain compression of cube oriented aluminium crystals

The influence of deformation temperature on the stability of the (001)[100] and (001)[110] orientations of Al and Al-1%Mn crystals has been determined by means of channel die tests at 200–400°C. X-ray pole figures and EBSP analyses demonstrate that the (001)[110] crystals decompose at all temperatures into deformation bands of complementary {112}〈11 1 〉 orientations. The behaviour of the cube orientation is temperature and strain rate dependent: at T < 0.6 T m (∼ 300°C) decomposition into bands of octahedral slip occurs whereas at higher temperatures the cube orientation deforms by double slip on {110}〈1 1 0〉 systems and is stable up to high strains ( ϵ ∼ 1.5). A simple analytical model and numerical simulations confirm that {110}〈1 1 0〉 slip affects the near-cube orientations and tends to stabilize the cube orientation; the latter can be considered as a hot rolling texture component.

The influence of deformation temperature under uniaxial stretching on the parameters of heat shrinkage of high density polyethylene

The influence of deformation temperature under uniaxial stretching on the nature of shrinkage stress and the change in linear dimensions of PE oriented samples during subsequent heating has been studied. It has been shown that thermal expansion of the material takes place in the initial stages of heating under orientation above the temperature of PE melting. Subsequent increase in temperature to that of PE melting causes the development of shrinkage stress and sample shrinkage. On orientation below the melting temperature, the heat expansion can be completely balanced, whereas sample shrinkage develops in the early stages of heating; high values of shrinkage stress are observed.

Spin dependent recombination at dislocations in silicon

The unpaired electrons of dislocations with an edge component in Si give rise to an EPR signal. Under the resonant condition, a decrease of photoconductivity is observed. We have observed the derivative of the resonant signal at a microwave frequency of 9.2 GHz by modulating the sweeping magnetic field. The relaxation time of the spin system was studied by varying the modulation frequency. The amplitude of the resonant signal is discussed with respect to dependence of the background signal on the sweeping magnetic field. The signal consists of more than one absorption line and has been resolved into its components by computer evaluation. The energy level structure of the dislocations which produce the signal has been derived from Hall effect measurements and conventional optical methods. The influence of deformation temperature and the role of other heat treatment produced defects as a possible source of the signal are discussed.The strength of the effect is related to the strong polarization of exchange coupled paramagnetic centers. The experimental results suggest that the recombination process is of the triplet type. The anomalous phase of the resonant signal is explained by resonant emission of microwave power.

Grain coarsening in Ti-5Al-2.5Sn

Grain coarsening in a Ti-5 Al-2.5 Sn titanium alloy, deformed in tension to 13 pct uniform elongation and then heated to 1144 K (1600°F) for one h, was investigated. The influence of deformation temperature (77 to 598 K), grain size (10.7, 11.8, and 22.5 μm), and strain rate (2.67 × 10-2, 6.67 × 10-4, 2.67 × 10-5 s-1) was also studied. Critical elongation and work input values for maximum grain coarsening varied with deformation temperature. The critical elongation value increased from 9 to 12 pct as the temperature decreased from 598 to 367 K and decreased from 12 to 9 pct as temperature decreased from 367 to 77 K. The critical work energy input increased linearly with decreasing temperature.