Role of shear strain in ultragrain refinement by accumulative roll-bonding (ARB) process

Lee, S.H; Saito, Yoshihiro; Tsuji, Nobuhiro; Utsunomiya, Hiroshi; Sakai, Tetsuo

doi:10.1016/s1359-6462(01)01239-8

Cited by 304 publications

(171 citation statements)

References 13 publications

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“…Even though ECR does not refine the grain size at the same level, it may lead Mg-alloys to have good H 2 storage properties because of the presence of preferential texture in the direction of the (002) basal plane of Mg 24,37,38,39 . The deformation of metals by ECR occurs under high friction and in a non-homogeneous way through their thickness because of the introduction of large amounts of redundant shear-strain on the material's surface 40 . Ueda et al 38 were one of the first to investigate ECR in the synthesis of materials for hydrogen storage when producing Mg-Ni using stacked sheets of Mg and Ni, followed by heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Severe Plastic Deformation and Additive Distribution in Mg-Fe to Improve Hydrogen Storage Properties

et al. 2017

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Magnesium (Mg) is a light metal with relatively low cost. Its hydride (MgH 2 ) is interesting for the safe hydrogen storage in solid state and has a high gravimetric capacity of 7.6%. Practical application of Mg is still hampered by high reaction temperatures and slow kinetics. In order to improve it and focus on more viable industrial processing conditions, Mg plates, with or without iron (Fe) addition, in the form of wires and powders, were submitted to severe plastic deformation (SPD) in air, starting with extensive cold rolling (ECR), followed by repetitive rolling (ARB). The samples were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning (SEM) and transmission electron microscopy (TEM). H 2 storage properties were evaluated by differential scanning calorimetry (DSC) and Sievert's volumetric method. Mg processed by ECR+ARB resulted in larger grain refinement and densities of cracks than ECR. In addition, Fe in the form of continuous wires was fragmented and resulted in a better distribution of particles than powders, which agglomerated. Thus, finally, the synergetic effect of microstructural features and Fe as catalyst and its distribution improved activation, kinetics and hydrogen storage capacity.

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Section: Introductionmentioning

confidence: 99%

Severe Plastic Deformation and Additive Distribution in Mg-Fe to Improve Hydrogen Storage Properties

et al. 2017

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“…These changes in the material properties near the surface and the higher hardness values are caused by work hardening due to large shear strain introduced by high friction during ARB. 42 This has an effect on the hardness in the center and near the bond layer due to the procedure of the ARB process because the surfaces are put in the middle of the specimen in the next cycle. Moreover, the high hardness values in the center of the specimens are also caused by the special precycle surface treatment wire brushing, which leads to the formation of a complex microstructure consisting of UFG and NC grains.…”

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confidence: 99%

Nanoindentation strain-rate jump tests for determining the local strain-rate sensitivity in nanocrystalline Ni and ultrafine-grained Al

et al. 2011

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A nanoindentation strain-rate jump technique has been developed for determining the local strainrate sensitivity (SRS) of nanocrystalline and ultrafine-grained (UFG) materials. The results of the new method are compared to conventional constant strain-rate nanoindentation experiments, macroscopic compression tests, and finite element modeling (FEM) simulations. The FEM simulations showed that nanoindentation tests should yield a similar SRS as uniaxial testing and generally a good agreement is found between nanoindentation strain-rate jump experiments and compression tests. However, a higher SRS is found in constant indentation strain-rate tests, which could be caused by the long indentation times required for tests at low indentation strain rates. The nanoindentation strain-rate jump technique thus offers the possibility to use single indentations for determining the SRS at low strain rates with strongly reduced testing times. For UFG-Al, extremely fine-grained regions around a bond layer exhibit a substantial higher SRS than bulk material.

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“…With increasing number of ARB cycles, θ decreases and the basal texture turns into single-peak basal texture. This is due to the sheet-stacking in ARB process [11]. It is known that single-peak basal texture is a shear texture or surface texture component of magnesium alloys [12] so that the texture forms beneath the surfaces.…”

Section: Resultsmentioning

confidence: 99%

Grain refinement of magnesium alloy sheets by ARB using high-speed rolling mill

Utsunomiya

Izumi

Sakai

et al. 2009

J. Phys.: Conf. Ser.

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Abstract. Applications of ARB to magnesium alloys were limited due to low deformability. The authors recently found that the rollability of the alloys is significantly improved in highspeed rolling. It is supposed that the severe plastic deformation of magnesium alloy sheets is feasible if rolling in ARB processes is conducted at high speed. In this study, AZ31B and ZK60A sheets are processed by ARB up to five cycles at 423K with a speed of 1000m/min. Vickers hardness increases with increasing number of ARB cycles, while the tensile strength shows the maximum after the second cycle. The grain size is reduced significantly at the first cycle and decreases gradually from the second cycle. The mean grain sizes after five cycles are 1.6µm for AZ31B and 1.8µm for ZK60A. It is concluded that ARB using high-speed rolling is effective for grain refinement of magnesium alloys.

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Role of shear strain in ultragrain refinement by accumulative roll-bonding (ARB) process

Cited by 304 publications

References 13 publications

Severe Plastic Deformation and Additive Distribution in Mg-Fe to Improve Hydrogen Storage Properties

Severe Plastic Deformation and Additive Distribution in Mg-Fe to Improve Hydrogen Storage Properties

Nanoindentation strain-rate jump tests for determining the local strain-rate sensitivity in nanocrystalline Ni and ultrafine-grained Al

Grain refinement of magnesium alloy sheets by ARB using high-speed rolling mill

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