Hot Equal Channel Angular Pressing Research Articles

Investigation of Severe Plastic Deformation Effects on Magnesium RZ5 Alloy Sheets Using a Modified Multi-Pass Equal Channel Angular Pressing (ECAP) Technique.

The present study investigates the effects of multiple passes of equal channel angular pressing (ECAP) on magnesium alloy sheets with the assistance of an Inconel plunger along with a die setup having a channel angle of 120° and corner angle of 10° operating at a temperature of 200 °C followed by the required heat treatment processes. The microstructural analysis of the sheet samples at various stages of the multi-pass hot ECAP has shown evidence of ultrafine grain refinement (UFG) due to the occurrence of severe plastic deformation. X-ray diffraction analysis has also exhibited the presence of phases like MgZn and CeZn3 which is supposedly responsible for the enhancement of the mechanical properties. As a result, the room temperature tensile and compressive strengths have improved by 6.12% and 6.63%, respectively, after the second pass, and 11.56% and 15.64%, respectively, after the fourth pass of ECAP. Additionally, the hardness of the sheets has increased by 6.49% and 16.64% after the second and fourth pass of hot ECAP, respectively, mainly attributed to the drastic decrease in grain size from 164 μm to 12 μm within four ECAP passes, all these with a negligible change in ductility. This success in the thermomechanical processing of Mg-RZ5 alloy sheets using a die channel angle of 120° with a minimal number of passes of hot ECAP under a controlled equivalent strain, further opens doors for incorporating optimizations and/or additional aspects so as to achieve even better grain refinements, and consequently, mechanical strength improvements thereby catering to the industrial needs of aerospace and construction areas.

Effects of Preheating Temperature on Deformed AA6061 Aluminium Properties of Hot Equal Channel Angular Pressing (ECAP) by Using Deform-3D Software

Effects of Preheating Temperature on Deformed AA6061 Aluminium Properties of Hot Equal Channel Angular Pressing (ECAP) by Using Deform-3D Software

The Effect of Solid-State Processes and Heat Treatment on the Properties of AA7075 Aluminum Waste Recycling Nanocomposite.

Direct solid-states, such as hot extrusion and equal channel angular pressing (ECAP), are alternative and efficient solid-state processes for use in recycling aluminium scrap. These processes utilise less energy and are eco-friendly. Ceramic particles such as ZrO2 are suggested as alternatives in the production of metal composites. This study investigated and optimised the effects of various parameters of reinforced ZrO2 nanoparticles on the mechanical and physical properties via response surface methodology (RSM). These parameters were the volume fraction (VF), preheating temperature (T), and preheating time (t). The effects of these parameters were examined before and after the heat treatment condition and ECAP. Each parameter was evaluated at varying magnitudes, i.e., 450, 500, and 550 °C for T, 1, 2, and 3 h for t, and 1, 3, and 5% for VF. The effect that process variables had on responses was elucidated using the factorial design with centre point analysis. T and VF were crucial for attaining the optimum ultimate tensile strength (UTS) and microhardness. Reducing VF increased the mechanical properties to 1 vol% of oxide. The maximum hardness of 95 HV was attained at 550 °C, 1.6 h, and 1 vol% ZrO2 with a density of 2.85 g/cm3 and tensile strength of 487 MPa. UTS, density, and microhardness were enhanced by 14%, 1%, and 9.5%, respectively. Additionally, the hot extrusion parameters and ECAP followed by heat treatment strengthened the microhardness by 64% and density by 3%. Compression pressure and extrusion stress produced in these stages were sufficient to eliminate voids that increased the mechanical properties.

Enhancing the strength of structural steel through severe plastic deformation based thermomechanical treatment

Structural steel (hypoeutectoid steel) was subject to severe deformation through a novel method of thermo-mechanical processing coupled with equal channel angular pressing (ECAP). The ECAP experiment was conducted at a specific temperature for the hot ECAP (H-ECAP) process after which the sample gained a superior strength of 811 MPa with reasonable elongation. Whereas when the ECAP was conducted at room temperature (RT-ECAP), the sample strength was 659 MPa with an elongation of 16%. The electron backscattered diffraction (EBSD) analysis revealed grain refinement and grain misorientation as a result of the ECAP process. The H-ECAP process resulted in an increased pearlite volume fraction and uniform pearlite fragmentation due to the strain induced transformation generated by hot deformation. The internal structural modification of the pearlite grain was revealed in the TEM micrographs. Nanoindentation analysis further exposed carbon supersaturation in the ferrite matrix. The X-ray line profile analysis (XRDLPA) illustrated that the H-ECAP processed sample has a higher dislocation density than the RT-ECAP processed sample. Factors such as grain refinement, morphological changes in the grains and the dislocation density predominantly contribute to the increased strength of the H-ECAP processed sample. In the overall observation, H-ECAP processed sample exhibited superior mechanical properties than the RT-ECAP processed sample.

STRUCTURE AND PROPERTIES OF AZ31 MAGNESIUM ALLOY AFTER COMBINATION OF HOT EXTRUSION AND ECAP

Equal channel angular pressing (ECAP) method was used for achieving very fine-grained structure and increased mechanical properties of AZ31 magnesium alloy. The experiments were focused on the, in the initial state, hot extruded alloy. ECAP process was realized at the temperature 250°C and following route Bc. It was found that combination of hot extrusion and ECAP leads to producing of material with significantly fine-grained structure and improves mechanical properties. Alloy structure after the fourth pass of ECAP tool with helix matrix 30° shows a fine-grained structure with average grain size of 2 μm to 3 μm and high disorientation between the grains. More experimental results are discussed in this article.

Solid-State Recycling of Light Metal Reinforced Inclusions by Equal Channel Angular Pressing: A Review

Solid-state recycling of light metals reinforced inclusions through hot Equal Channel Angular Pressing (ECAP) is performed to directly recycle metal scraps and reduce cost of material in engineering applications. The ECAP is one of the most important method in severe plastic deformation (SPD) that can convert light metals into finished products. This paper reviews several experimental and numerical works that have been done to investigate the effects of the ECAP parameters such as die angles, material properties, outer corner angle, friction coefficient, temperature, size of chips, pressing force, ram speed and direct effects of number of passes on the strain distributions. It also includes the performance enhancement of aluminium matrix composite reinforced ceramic-based particles that derived from direct recycled aluminium chips for sustainable manufacturing practices.

Low-Temperature Superplasticity in an Al–Mg–Mn Alloy Subjected to ECAP and Subsequent Isothermal Rolling

An ultra-fine grained structure with an average size of ~ 1 μm was produced in a commercial Al–5.4%Mg–0.5%Mn–0.1%Zr–0.12%Si–0.014%Fe alloy by hot equal-channel angular pressing (ECAP) followed by isothermal rolling (IR). It was found that in the strain rate interval from 5.6×10-4 to 2.8×10-2 s-1 the alloy exhibits a low-temperature superplasticity with elongation-to-failure exceeding 400% and the strain rate sensitivity coefficient of ~0.3. The highest elongation-to-failure of ~ 620% appeared at a temperature of ~ 275°C and an initial strain rate of ~ 5.6×10-3 s-1. The relationship between superplastic properties and microstructural evolution of the examined alloy is discussed.

The microstructural evolution and superplastic behavior at low temperatures of Mg–5.00Zn–0.92Y–0.16Zr (wt.%) alloys after hot extrusion and ECAP process

Abstract In this study, equal channel angular pressing (ECAP) was applied to a hot-extruded Mg–5.00Zn–0.92Y–0.16Zr (wt.%) alloy to produce an ultrafine-grained a -Mg structure of 0.6 μm with uniformly distributed fine quasicrystal Mg 3 YZn 6 particles. The basal planes in the as-ECAPed alloy were inclined approximately 45° to the ECAP direction (EPD); thus, a high Schmid factor of 0.36 for ( 0 0 0 1 ) 〈 1 1 2 ¯ 0 〉 basal slip along EPD was obtained. Then, the superplastic behavior at low temperatures of 150–250 °C and initial strain rates of 1.67 × 10 −3 s −1 –1.67 × 10 −1 s −1 of the as-ECAPed alloy was investigated and compared with that of the as-extruded alloy. The microstructural development, texture evolution and cracking behavior during tensile tests were systemically investigated by electron backscattered diffraction (EBSD) analysis. During the tensile test along the EPD, the basal planes in the as-ECAPed alloy specimen were tilted approximately 15° away from the original position; thus, the basal planes were still in a position favorable for the basal slip along the EPD. As a result, a maximum elongation of 865% was obtained at 200 °C and a strain rate of 1.67 × 10 −3 s −1 , as a result of this favored basal texture and the excellent thermal stability of the ultrafine-grained structure. This optimum superplastic temperature of 200 °C is much lower than that obtained for other Mg–Zn–Y–(Zr) alloys. In contrast, for the as-extruded alloy specimen, superplastic behavior did not occur until the critical condition of 250 °C and a strain rate of 1.67 × 10 −3 s −1 . Below this temperature and strain rate, the strong extrusion basal texture was maintained, and the cracks in the hot-worked coarse region (or un-DRXed region) were observed nucleating mainly associated with the formation of a 38° { 1 0 1 ¯ 1 } – { 1 0 1 ¯ 2 } double twin. At this temperature and strain rate, the hot-worked coarse regions were significantly refined by the dynamic recovery and the following recrystallization process. In the case, the formation of a double twin was prevented and the facture was delayed.

Partial Grain Refinement in Al-3%Cu Alloy during ECAP at Elevated Temperatures

Microstructural changes during equal channel angular pressing (ECAP) in a temperature interval from 523 to 748 K (� 0:6{0:8 Tm) were studied in a coarse-grained binary aluminum alloy Al-3%Cu. Hot ECAP results in grain refinement taking place at all temperatures investigated, leading to a non-uniform development of deformation-induced fine grains and the remnant original grains containing subgrains with low-angle boundaries. Fine-grained structure is developed along microshear bands formed in grain interiors as well as along initial grain boundaries. The number and the average misorientation angle of the boundaries of microshear bands start to increase at above a critical strain of about 2, finally leading to development of new fine-grained structures. The volume fraction and the average misorientation of deformation-induced boundaries are reduced with rising temperature. The thermal stability of the evolved deformation microstructures and several factors controlling grain refinement during hot ECAP are discussed in details. [doi:10.2320/matertrans.MD200807]

Grain Refinement in a Commercial Al-Mg-Sc-Zr Alloy during Hot ECAP

The microstructure evolution of an as-cast commercial Al-Mg-Sc-Zr alloy during Equal- Channel Angular Pressing (ECAP) at 325°C was investigated. In the early stages of deformation strain induced boundaries were created within the initial coarse grains and constitute the deformation bands. Repeated ECAP led to an increase of the number and misorientation of deformation bands. Further straining up to e~8 resulted in the formation of a new fine-grained structure with an average crystallite size of 1.2 /m. It is concluded that the progressive increase of the misorientation of deformation induced boundaries is the main mechanism of structure formation under high temperature ECAP.

Development of microstructure and mechanical properties of as cast Al–Mg–Mn alloy during high temperature ECAP

A large scale billet with diameter of 58·5 mm of an as cast Al–Mg–Mn alloy was processed by equal channel angular pressing (ECAP) at 350°C up to six passes. A significant refinement of the grains was observed after six pressings to ∼2 μm. And the selected area electron diffraction (SAED) pattern showed that almost all of the grains were separated by boundaries with high angles of misorientation. A banded substructure was not observed during the hot ECAP, and a reasonably equiaxed structure was obtained just after one single pressing. Both the strength and the elongation increased abruptly in a single passage through the die, but thereafter, the increase was more gradual and exhibited a saturation effect after the fourth pressing. The good combination of strength and ductility of the Al–Mg–Mn alloy attained by the hot ECAP appeared to be attractive properties for industrial applications. Moreover, hot ECAP could possibly be used as an alternative step to hot extrusion or hot rolling in industrial processing, to break down an initial coarse as cast structure in a quite large scale billet.

Effect of deformation temperature on microstructure evolution in aluminum alloy 2219 during hot ECAP

The effect of deformation temperature on microstructure evolution during equal channel angular pressing (ECAP) was studied in a coarse-grained aluminum alloy 2219 in a wide temperature interval from 250 to 475 °C. The structural changes taking place during ECAP up to strains of 12 are classified into the following three stages irrespective of deformation temperatures: i.e. (1) an incubation period for formation of the embryos of deformation bands (DBs) at low strains; (2) development of large-scale DBs followed by grain fragmentation at moderate strains; (3) rapid development of new grain at high strains. Microstructure development in stages 1 and 2 is hardly influenced by temperature, while that in stage 3 is most significantly affected at higher temperature. An increase in the pressing temperature leads to decreasing the volume fraction of new grains and increasing the average grain size in stage 3. This can be attributed to relaxation of strain compatibility between grains due to frequent operation of dynamic recovery and grain boundary sliding at higher temperature. The mechanism of grain refinement is discussed in detail.

Effect of ECAP Hot Processing on Grain Refinement and Superplasticity of 1933 Aluminium Alloy

Cold and hot Equal-Channel Angular Pressing (ECAP) is an effective method to refine metallic grains. In this paper, superplastic properties of 1933 aluminium alloy were evaluated and the effect of hot ECAP on grain refinement and superplasticity was investigated. The testing results show that the refinement of grains can not be infinitely increased with the increasing of ECAP passes (or total strain). Under the isothermal ECAP conditions of the present study, optimum ECAP passes for 1933 alloy are 4 passes. The grain size of 1933 alloy was refined from 20~50μm to 7~12μm by means of ECAP for 4 passes at 300°C (route Bc), so its superplasticity was improved. Compared with original samples annealed at 400°C, the superplastic elongation of samples processed by ECAP for 4 passes increases by a factor of 130% about, and the range of superplastic temperature varies from 140°C to 210°C. The optimal superplastic temperature and initial strain rate is 510°C and 3.3×10-4s-1 individually, at which the elongation reaches 262% and the flow stress is 7.8MPa only. In a word, 1933 aluminium alloy can present more excellent superplasticity in wide range of superplastic temperature and strain rate.

Mechanical properties and microstructure of Al–Mg–Mn–Zr alloy processed by equal channel angular pressing at elevated temperature

An Al–Mg–Mn alloy containing Zr, and a standard 5083Al alloy were fabricated. The as-cast alloys were homogenized, hot extruded and hot ECAP (equal channel angular pressing). After hot extrusion, the ultimate strength of the Al–Mg–Mn–Zr alloy was 30.0 MPa higher than that of 5083Al, but the elongation was 10.1% lower. This was because the Al 3Zr dispersoids in the Al–Mg–Mn–Zr alloy enhanced the strength and inhibited the recovery process during the hot extrusion, but simultaneously decreased the ductility. After hot ECAP, the strength of the Al–Mg–Mn–Zr alloy was still 32.6 MPa higher than that of 5083Al but without significant loss of the elongation. This implied that the fine-grained, high-angle boundaries microstructure produced by hot ECAP can effectively enhance the strength with little compromise of the ductility of the Zr-modified alloy.

Grain refinement in a commercial Al–Mg–Sc alloy under hot ECAP conditions

Grain refinement taking place during equal-channel angular pressing (ECAP) was studied in a commercial Al–6% Mg–0.4% Mn–0.3% Sc alloy at a temperature of 450 °C (∼0.8 T m) to demonstrate the feasibility of obtaining new fine-grained structure in a hard-to-deform Al–Mg–Sc alloy under hot intense plastic straining (IPS) conditions and investigate the evolution process of new grains. Inhomogeneous deformation occurring during hot ECAP leads to formation of deformation bands. Repeated ECAP results in mutual crossing and increase in number and the misorientation of deformation bands, followed by transformation of the boundaries of deformation bands into high-angle ones. As a result, a new fine-grained microstructure with an average crystallite size of 2.8 μm develops at large strains above 8. It is concluded that grain refinement occurs in accordance with deformation-induced continuous reactions; that is similar to in-situ or continuous dynamic recrystallization. The mechanisms of new grain evolution, as well as factors promoting grain refinement, are discussed in detail.