Influence of strain rate on deformation behaviour of an AX52 alloy processed by equal channel angular pressing (ECAP) (original) (raw)
Related papers
Materials Characterization, 2017
The influence of three different equal channel angular pressing (ECAP) routes (A, Bc and C) on the grain size, texture, dislocation structure and mechanical properties in pre-extruded AX41 magnesium alloy was investigated. It was found that during the first passes, the rate of grain fragmentation strongly depends on the processing route. After 8 passes, despite the almost identical values of the dislocation density (0.7 × 10 14 m −2), the average grain size varied in the range of 2.0-4.5 μm for the individual ECAP routes. Macroscopic texture measurements revealed a gradual formation of very strong textures, which were significantly different for the various processing routes. The strength and the ductility of the samples were investigated by tensile test carried out parallel to the outgoing channel axis. Route A was found to be the most effective processing route for grain refinement. In tensile tests carried out at room and elevated temperatures, the highest strength was observed for the sample processed via route A for 8 passes, due to the highest texture hardening and the smallest grain size.
Journal of Alloys and Compounds, 2017
The objective of this study is the investigation of the effect of temperature of equal channel angular pressing (ECAP) on the microstructure, texture and mechanical properties of AX41 magnesium alloy. ECAP processing was performed at temperatures of 220 C and 250 C up to 8 passes via route Bc. It was found that during ECAP processing at 250 C a smaller number of passes was enough to achieve a homogeneous microstructure than at 220 C. However, the final grain size obtained after 8 passes at 250 C was only 4 mm which is larger than the value of 2.7 mm achieved at 220 C. Moreover, a significant influence of the temperature of ECAP processing on the dislocation density and the crystallographic texture was observed. The proof stress of the sample processed by 8 passes at 250 C was lower than that obtained at 220 C. It can be attributed to the lower dislocation density, the larger grain size and the texture, which facilitates the basal slip.
Strain Distribution in Equal Channel Angular Pressing of AM60 Magnesium Alloy
2021
In this research, the equal channel angular pressing (ECAP) process of AM60 magnesium alloy was investigated by the finite element simulation as well as experimental test. The effect of process parameters on required force and strain distribution was also assessed. The simulation results were verified by the experimental tests. Using the full factorial design of experiments, effects of friction and process temperature were explored. The results indicated that an increase in the friction coefficient will significantly enhance the amount of pressing force (4-fold). Also, the effect of friction on process force was higher at lower temperatures and decreased with the rise of temperature. An increment in the friction coefficient from 0.02 to 0.08 raised the maximum strain by 9%. Furthermore, the maximum strain showed enhancement with temperature elevation.
Micro-Tensile Behavior of Mg-Al-Zn Alloy Processed by Equal Channel Angular Pressing (ECAP)
Materials
Commercially available AZ31 magnesium alloy was four times extruded in an equal rectangular channel using three different routes (A, B, and C). Micro tensile deformation tests were performed at room temperature with the aim to reveal any plastic anisotropy developed during the extrusion. Samples for micro tensile experiments were cut from extruded billets in different orientations with respect to the pressing direction. Information about the microstructure of samples was obtained using the electron back-scatter diffraction (EBSD) technique. Deformation characteristics (yield stress, ultimate tensile stress and uniform elongation) exhibited significant anisotropy as a consequence of different orientations between the stress direction and texture and thus different deformation mechanisms.
Deformation behavior of an ultrafine-grained Al–Mg alloy produced by equal-channel angular pressing
Acta Materialia, 2007
Presented here is the deformation behavior of Al-1.5 wt% Mg alloy severely plastically deformed to equivalent pre-strains of 8 and 13 using the equal-channel angular pressing technique. The average subgrain size after severe plastic deformation was 280 and 230 nm respectively. Strain rate change and stress relaxation tests in the range 10 À4 -10 À2 s À1 and 298-523 K were performed. The strain rate sensitivity of ultrafine-grained (UFG) Al-1.5Mg was enhanced and the peak strain rate sensitivity shifted to lower temperatures as compared with the coarse-grained (CG) alloy. The increased strain rate sensitivity is a direct consequence of the reduced activation volume. The increase in pre-strain from 8 to 13 has a small effect on both the microstructural refinement and the subsequent deformation behavior. With increasing temperature the UFG material softens compared with the CG material. This demarcation has been clearly shown on a strain rate by temperature plot. Refinement of grain results in an enhanced solute drag regime, primarily due to the decreased activation energy of diffusion.
Journal of Materials Science, 2018
This study investigates the influence of the initial state of the commercial AX41 magnesium alloy on the microstructure evolution and mechanical properties after equal-channel angular pressing. Two initial conditions, an as-cast one with a grain size of 200 lm and a random crystallographic texture, and an extruded one having a grain size of 10 lm and a strong fibre texture, are compared. ECAP processing was performed at the temperature of 220°C up to 8 passes via route B C. A much smaller grain size was obtained in the ECAP-processed as-cast material compared to the extruded one. This difference was attributed to the different evolution of the dislocation density and its fractions in different slip systems. Consequently, different refinement mechanisms were dominant in the later stage of ECAP processing. It was shown that ECAP processing leads to the formation of similar crystallographic textures for both initial states, having dominant basal texture component. The mechanical properties investigation showed improvement in the microhardness, tensile strength and elongation in both ECAP-processed samples.
Materials Science and Engineering: A, 2008
Equal channel angular pressing (ECAP) was applied to a wrought magnesium alloy AZ31 for up to 8 passes at temperatures as low as 100 • C. The application of a back pressure was critical in deforming Mg alloys at lower temperatures. Room temperature mechanical properties were obtained by tensile and hardness tests. With increasing ECAP strain, the initial coarse grained structure was transformed into a submicrometergrained microstructure. In general, hardness increased with decreasing grain size although the changes in tensile strength and ductility were more complicated.
Evolution of the Microstructure of Al 6082 Alloy during Equal-Channel Angular Pressing
Materials Science Forum, 2005
A commercial Al-Mg-Si alloy (Al 6082) was deformed by Equal-Channel Angular Pressing (ECAP) to produce bulk ultrafine-grained microstructure. The crystallite size distribution and the characteristic parameters of the dislocation structure were investigated by X-ray diffraction profile analysis. It was found that the crystallite size decreased and the dislocation density increased during ECAP deformation. The increase of the yield stress of the alloy was related to the increase of the dislocation density using the Taylor model. Materials Science Forum Vols. 473-474 (2005) pp. 453-458 online at http://www.scientific.net
Enhancement of Mechanical Properties for Al-Mg-Si Alloy Using Equal Channel Angular Pressing
—Equal channel angular pressing (ECAP) of commercial Al-Mg-Si alloy was conducted using two strain rates. The ECAP processing was conducted at room temperature and at 250°C. Route A was adopted up to a total number of four passes in the present work. Structural evolution of the aluminum alloy discs was investigated before and after ECAP processing using optical microscopy (OM). Following ECAP, simple compression tests and Vicker's hardness were performed. OM micrographs showed that, the average grain size of the as-received Al-Mg-Si disc tends to be larger than the size of the ECAP processed discs. Moreover, significant difference in the grain morphologies of the as-received and processed discs was observed. Intensity of deformation was observed via the alignment of the Al-Mg-Si consolidated particles (grains) in the direction of shear, which increased with increasing the number of passes via ECAP. Increasing the number of passes up to 4 resulted in increasing the grains aspect ratio up to ~5. It was found that the pressing temperature has a significant influence on the microstructure, Hv-values, and compressive strength of the processed discs. Hardness measurements demonstrated that 1-pass resulted in increase of Hv-value by 42% compared to that of the as-received alloy. 4-passes of ECAP processing resulted in additional increase in the Hv-value. A similar trend was observed for the yield and compressive strength. Experimental data of the Hv-values demonstrated that there is a lack of any significant dependence on the processing strain rate.