Effect Of Equal Channel Angular Extrusion Research Articles

Influence of equal-channel angular extrusion on impact toughness of aluminum and brass at room and low temperatures

Abstract Background Equal-channel angular extrusion is a severe plastic deformation process that can be used for grain refinement to improve material properties of bulk metals. In this paper, the effect of equal-channel angular extrusion on the impact toughness of aluminum 1100 and brass C26000 was investigated. Methods Brass and aluminum materials were extruded in two and four passes using two equal-channel angular extrusion processing routes. Specimens were tested for hardness and Charpy impact toughness. Microstructure and fractography were examined. Results The results showed the hardness remained almost constant after two passes for both brass and aluminum. Impact energy of brass after two passes decreased due to increase in dislocation density whereas for aluminum it remained almost constant after four passes due to the formation of ultrafine grains in addition to deformation/dislocation structures. Impact energies of specimens tested at room temperature and low temperature (−70°C) were almost the same due to their face-centered crystal structure. It was also found that the impact toughness of a specimen with a non-distorted notch surface is higher than that of a specimen with a distorted notch surface. Conclusions It is evident from the present study that the number of passes determines the extent of ultrafine grain structure that is known to increase impact toughness of equal-channel angular extrusion processed materials. All of these observed characteristics can influence material and process selections in practical design applications.

Effect of ECAE on Structure and Strength of Porous A6061 Alloy with Aligned Unidirectional Pores

Deformation behavior of porous aluminum alloys with aligned unidirectional pores through equal-channel angular extrusion (ECAE) was investigated. The porous aluminum alloys were fabricated by dipping pure aluminum pipes into semi-solid slurry base metal. The pipes did not detach from the base metal even through the ECAE process. Comparing the sample dimension of pores before and after ECAE process, the amount of decrease in a dimension of pores was 19.4% in this study. The Vickers hardness increased by work hardening. Especially, the hardness value of area where plastic flow arose increased significantly. These results show that we can improve the mechanical properties with maintenance of the porous structure and measure the amount of the sample deformation quantitatively.

The Tribological Properties of Mg Alloy Produced by ECAE and Laser Melting

A new processing procedure was applied to an Mg alloy. This procedure involves the equal channel angular extrusion (ECAE) process and laser melting surface treatment. A commercial Mg alloy was first produced by equal channel angular extrusion (ECAE) process. Then the laser melting surfave treatment was carried out after ECAE. The effects of ECAE and laser melting on tribological properties of the alloy were investigated. Experimental results showed that the mechanical properties and tribological properties of the alloy were improved after ECAE. The laser melting surface treatment can further improve the tribological properties of Mg alloy.

Wear Behavior of Mg Alloy Procduced by Equal Channel Angular Extrusion

A commercial Mg alloy was prepared through equal channel angular extrusion (ECAE) process. The effect of ECAE on mechanical and tribological properties of the alloy was investigated. Experimental results showed that the hardness and strength of the alloy with ECAE were higher than that of the alloy without ECAE and increased with the increase pass number. The friction coefficient and wear resistance of the alloy after ECAE were significantly improved.

The Effect of Equal-Channel Angular Extrusion to the Cast Aluminum Alloy Materials

With the rapid development of modern world aerospace science and technology, hi-tech weaponry and high-speed transportation tools, industrial production and high-tech equipment manufacturers have increasingly urgent demand for high-performance metal materials. The cast aluminum is a new aluminum alloy series developed by foundry industry recently. Because it does not need the solid solution hardening process and has good mechanical properties, it's loved by the manufacturing sector. This paper targets at channel angular deformation direction to study the cast aluminum tissue material .

Effect of ECAE-processing on the thermo-mechanical behavior of Ti34 wt.%Nb0.14 wt.%O shape memory alloy

Abstract The effect of ECAE (equal channel angular extrusion)-processing on the thermo-mechanical behavior of Ti34 wt.%Nb0.14 wt.%O shape memory alloy was studied by measuring the tensile stress–strain curve at various temperatures and using DSC, X-ray diffraction, and TEM. An ultrafine (0.4 μm) grain structure was developed by severe plastic deformation and by the formation of alpha-particles on grain boundaries, which was facilitated by oxygen. Severe grain refinement led to a large decrease of Ms from 216 °C to 106 °C. Furthermore, the elimination of oxygen by α-particles led to an abrupt decrease of the stress for reorienting the martensite variants and to an increase in the transformation strain. Subsequent ω-aging treatment further stabilized the β-phase at room temperature, resulting in a superelastic property.

Effects of ECAE and Aging on Phase Transformations and Superelasticity of a Ni-Rich TiNi SMA

Effects of equal-channel angular extrusion (ECAE) process at 773K and heat treatment on phase transformations and superelasticity of a Ni-rich TiNi shape memory alloy were investigated by differential scanning calorimeter (DSC) measurement and cyclic tensile test. The R phase transformation of Ni-rich TiNi alloy was stimulated after ECAE processes and within a larger temperature range. The martensitic transformation start temperature Ms of Ni-rich TiNi alloy decreased sharply after ECAE processes at 773 K, then rapidly rose back after the specimen aging at 773K for 30min. Reasons for the changes of phase transformation behaviors have been discussed. ECAE processed TiNi samples exhibit better super-elasticity than solution treated one. With the increase passes of ECAE, the superelasticity becomes more stable, and a completely recoverable strain of 6% is obtained for TiNi sample after 8 passes ECAE.

Microstructure and Wear Properties of GCr15 Alloy Produced by Equal Channel Angular Extrusion

GCr15 alloy produced by hot-forged is subjected to equal channel angular extrusion (ECAE) process at 950°C. The microstructure of GCr15 steel via ECAE and annealed is studied by an optical microscope. The effect of ECAE and annealing on the wear properties of the alloy is also investigated. The results show that the grain size reduced from 50 mm to 10 mm via one pass ECAE, and the hardness of the alloy is increased. The wear mass loss of the alloy is greatly reduced due to the grain-refinement after ECAE and annealing.

Effect of equal-channel angular extrusion on the mechanical and tribological properties of as-cast Zn–40Al–2Cu–2Si alloy

As-cast Zn–40Al–2Cu–2Si alloy was processed using equal-channel angular extrusion/pressing (ECAE/P) at 230 °C for four passes following route-B C. After processing, the room temperature mechanical properties (strength, ductility and impact toughness) and dry sliding wear and friction characteristics of the alloy were investigated. After four-pass ECAE, the tensile elongation to fracture of the alloy increased from 0.8% to 14.4% without a considerable decrease in its strength values. The impact toughness also increased and the as-cast brittle alloy was transformed into a ductile and tougher alloy after processing. Such enhancements are attributed to the breakage of large dendrites and fragmentation of copper-rich-phase and Si particles into finer structures, and deformation-induced homogenization of the microstructure during multi-pass ECAE. Wear resistance of ECAE-processed Zn–40Al–2Cu–2Si alloy was notably improved especially at longer sliding distances and under higher applied pressures compared to the as-cast alloy. It was also found that the ECAE processing decreased the friction coefficient of the alloy.

Effect of equal-channel angular extrusion on mechanical and wear properties of eutectic Al–12Si alloy

Mechanical and wear properties of severely deformed Al–12Si alloy by equal-channel angular extrusion/pressing (ECAE/P) were investigated. Multi-pass ECAE processing of the as-cast alloy substantially increased both its strength and ductility. The increase in the tensile and yield strength values after six ECAE passes were about 48% and 87%, respectively. The sample after six ECAE passes exhibited 10% elongation before rupture, which was about five times higher than that of the as-cast one. The improvement in both strength and ductility was mainly attributed to the changes of the shape, size and distribution of the eutectic silicon particles along with the breakage and refined of the large α-Al grains during multi-pass ECAE processing. However, the wear test results surprisingly showed that the ECAE process decreased the wear resistance of the alloy, although there was improvement in strength and ductility values. This was mainly attributed to the tribochemical reaction leading to oxidative wear with the abrasive effect in Al–Si alloys during sliding. The oxide layer played a dominant role in determining the wear resistance of the sample in both as-cast and ECAE-processed states, and it masked the effect of strengthening of alloy structure on the wear resistance.

Effects of ECAE on Plastic Deformation Behavior of Glassy Polymers

We examined applicability of equal channel angular extrusion (ECAE) to improvement of plastic deformability of glassy polymers. Polycarbonate (PC) and poly(methyl methacrylate) (PMMA) were extruded at various temperatures ranging from 50°C to just below the glass transition temperature through one of three equal channel angular dies (ECA-dies) having a pass angle 2φ of 90°, 120° and 150°. Both PC and PMMA could successfully be extruded at most of all conditions examined in this study, although PMMA could not be extrudable at temperatures below about 60°C. After processed through ECAE, extruded PC and PMMA were subjected to tensile test. It was found that ECAE lessened the tensile yield stress of the glassy polymers when extrusion was performed at a lower temperature and through an ECA-die with a larger pass angle 2φ. Plastic flow stress did not so much increase in polymers extruded through an ECA-die with a larger 2φ. Thus, ECAE at a lower temperature through a die with a larger pass angle 2φ was found to be effective to improve plastic deformability of glassy polymers.

RETRACTED: The improvement of tribological behaviors of Cu–15%Al–4%Fe alloy by equal channel angular extrusion technique

A commercial aluminum bronze alloy (Cu―15%Al―4%Fe) produced by hot-rolling was subjected to equal channel angular extrusion (ECAE) process at high temperature. The effect of ECAE on microstructure, mechanical and tribological properties of the alloy was investigated. Experimental results showed that grain size decreased and the second phase was rearranged after ECAE. The hardness and strength of the alloy with ECAE were higher than that of the alloy without ECAE and increased with the increase pass number. The wear resistance of the alloy after ECAE was significantly improved.

Combining Equal-Channel Angular Extrusion (ECAE) and Heat Treatment for Achieving High Strength and Moderate Ductility in an Al-Cu Alloy

The effect of equal-channel angular extrusion (ECAE) on mechanical properties of an AA2017 produced by powder metallurgy is investigated. Special attention is given to the influence of heat treatment, processing temperature and backpressure on the workability for achieving high strength and moderate ductility. This is of special interest, since it is often reported that Al-Cu alloys have low ductility and therefore are prone to cracking during severe plastic deformation. It is shown that ECAE at high temperatures (>220°C) does not necessitate backpressure to ensure homogeneous deformation but leads to a significant sacrifice in strength due to in-situ precipitation. Thus, most of the extrusions are done at considerably low temperatures. Performing room temperature-extrusion is most effective in achieving high strengths but also requires high backpressures. Due to severe strain hardening during processing, the strength increase is combined with a reduction in ductility. Recently it was reported that a post-ECAE aging of pre-ECAE solution treated material is effective in enhancing the ductility of aluminium alloys. This approach was successfully transferred to the current alloy. A high-temperature, short-time aging after only one extrusion, for example, doubles the failure strain to a value of ~13%. Compared to the naturally aged condition with coarse grains that serves as reference (T4), an increase of 15 % in yield stress (YS) was obtained while retaining the ultimate tensile stress (UTS). Another effective approach is the combination of a pre-ECAE solution treatment with subsequent under-aging prior to ECAE. It is shown that performing ECAE at medium temperatures (160-180°C) enables a better workability and additionally gives higher strengths and better ductility compared to the processing in the water quenched condition. A remarkable YS of 530 MPa and an UTS of 580 MPa combined with a moderate failure strain of 11.6 % were achieved.

Microstructure and dry sliding wear behavior of Cu–10%Al–4%Fe alloy produced by equal channel angular extrusion

A commercial aluminum bronze alloy (Cu–10%Al–4%Fe) produced by hot-rolling was subjected to equal channel angular extrusion (ECAE) process at high temperature. The effect of ECAE on microstructure, mechanical and tribological properties of the alloy was investigated. Experimental results showed that grain size decreased and the second phase was rearranged after ECAE. The hardness and strength of the alloy with ECAE were higher than that of the alloy without ECAE and increased with the increase pass number. The wear resistance of the alloy after ECAE was significantly improved.

Effects of equal channel angular extrusion and subsequent heat treatment on tribological properties of TiNi alloy

The friction and wear properties of TiNi alloy processed by equal channel angular extrusion (ECAE) and subsequent heat treatment processing under dry sliding condition were evaluated on a block on ring M-2000 tribometer. The effects of ECAE and heat treatment on the tribological properties of TiNi alloy were investigated. The worn surface morphologies of TiNi alloy were examined by scanning electron microscopy (SEM) and the wear mechanisms were discussed. The results showed that ECAE and heat treatment contributed to improve the friction and wear behaviours of TiNi alloy remarkably. The friction coefficient and wear loss of TiNi alloy decreased after ECAE and heat treatment. The maximum wear reduction was obtained when the heat treatment temperature after ECAE was 773 K. Adhesion wear and delamination were notable for the initial TiNi alloy. The material delamination was greatly abated when the heat treatment temperature of TiNi alloy processed by ECAE was 773 K.

Effect of ECAE on Microstructure and Tribological Properties of Cu–10%Al–4%Fe Alloy

Equal channel angular extrusion (ECAE) process was carried out for a commercial aluminum bronze alloy (Cu–10%Al–4%Fe) produced by hotrolling at high temperature. The effect of ECAE on microstructure, mechanical, and tribological properties of the alloy was investigated. Experimental results showed that the grain size of the alloy decreased with the increase of the pass number of ECAE. After applying ECAE with six passes, the hardness and yield strength of the alloy increased from 118 kgf/mm2 and 356 MPa to 165 kgf/mm2 and 588 MPa, respectively. The friction coefficient and wear rate of the aluminum bronze alloy were largely reduced due to the improvement of mechanical properties after ECAE. The adhesive wear was the primary wear mechanism for the specimen without ECAE, while abrasive wear was dominant for the specimen with ECAE after six passes.

Microstructure and mechanical properties of Cu–10%Al–4%Fe alloy produced by equal channel angular extrusion

A commercial aluminum bronze alloy (Cu–10%Al–4%Fe) produced by hot-rolling was subjected to equal channel angular extrusion (ECAE) process at 550 °C, 600 °C and 650 °C, respectively. The effects of ECAE on microstructure, phase transformation behavior and mechanical properties of the alloy were investigated. The results showed that the extrusion temperature must be higher than the eutectoid reaction temperature of the alloy. The grain size of alloy gradually reduced with the increase of the pass number of ECAE, and the mechanical properties were significantly improved after ECAE. In addition, phase transformation temperature of the alloy can be reduced by ECAE process.

Mechanical Properties of Ultra-Fine Grained Al-Li Alloys

The results obtained in the present study reveal the effect of equal channel angular extrusion (ECAE) on the grain size and mechanical properties of Al-Li alloys. During 8 passes of ECAE process, coarse grain microstructure in the initial state transforms into ultrafine grained. The final grain size depends on both total strain applied and Li content in the alloy. Due to the grain refinement the microhardness and yield stress increase by 100%. During compression deformation, the coarse grain alloys exhibit continuous hardening, whereas in the ultrafine-grained alloys, a stagnation of work hardening at the beginning of compression deformation is observed. This behaviour is related to the dynamic recovery of the severely deformed microstructure.

Structure and mechanical properties of commercial Al–Mg 1560 alloy after equal-channel angular extrusion and annealing

Structure-property relationships in commercial 1560 (Al–6.0 wt.% Mg–0.6 wt.% Mn) aluminium alloy subjected to equal-channel angular extrusion (ECAE) and subsequent annealing have been analyzed. The features of the submicrocrystalline (SMC) deformation structure obtained by ECAE and its transformation into submicro- and microcrystalline grain structures upon annealing were studied by optical and transmission electron microscopy, and X-ray diffraction. The nature of recrystallization and phase transformation processes upon annealing is discussed. The alloy mechanical behaviour has been characterized by static tension and bending experiments at room temperature. The effects of ECAE and annealing on serrated flow, strength, hardness, ductility and crack resistance of the alloy are demonstrated. In contrast to the usually observed behaviour of ECAE-processed Al alloys, ductility and crack resistance decreased with transformation the SMC structure upon low-temperature annealing, which is attributed to the formation of β precipitates during annealing treatment.