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Journal ArticleDOI

A Process of Notch Wavy Rolling for Strengthening Metal Sheets

TL;DR: In this paper, a sine wave shape (wave amplitude <2mm) was used for strengthening 1mm thin austenitic stainless steel coil sheet by cold rolling without further reduction in thickness.
Abstract: Wavy roll design was employed for strengthening 1 mm thin austenitic stainless steel coil sheet by cold rolling without further reduction in thickness. This steel possesses high corrosion resistance and high ductility. Initially, the sheets were rolled into sine wave shape (wave amplitude <2 mm) and then flattened using conventional cold rolling mill. Such a process cycle was repeated for four times successfully and the mechanical properties were measured after each cycle. The yield strength increased from 255 to 931 MPa with corresponding decrease in elongation from 45% to only 17% after the fourth cycle of severe cold working. Tensile strength and hardness values increased from 753 MPa and 185 HV to 973 MPa and 371 HV, respectively. The micro-to-nano-scale resolution structures, obtained by optical and atomic force microscope (AFM), were used to explain the variation in properties during this manufacturing process and to propose schematically the deformation mechanism.
Citations
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Journal ArticleDOI
TL;DR: An alternative method to improve both strength and formability of cryorolled sheets by warm forming without any post-heat treatment is proposed in this paper, where the formability is characterized in terms of forming limit diagrams (FLDs) and limiting dome height (LDH).
Abstract: Cryorolling is a severe plastic deformation (SPD) process used to obtain ultrafine-grained aluminum alloy sheets along with higher strength and hardness than in conventional cold rolling, but it results in poor formability. An alternative method to improve both strength and formability of cryorolled sheets by warm forming after cryorolling without any post-heat treatment is proposed in this work. The formability of cryorolled AA6061 Al alloy sheets in the warm working temperature range is characterized in terms of forming limit diagrams (FLDs) and limiting dome height (LDH). Strain distributions and thinning in biaxially stretched samples are studied. Hardness of the formed samples is correlated with ultimate tensile strength to estimate post-forming mechanical properties. The limit strains and LDH have been found to be higher than in the case of the conventional processing route (cold rolled, annealed and formed at room temperature), making this hybrid route capable of producing sheet metal parts...

27 citations

Journal ArticleDOI
TL;DR: In this paper, equal channel angular pressing (ECAP) was applied on AM90 magnesium alloy using processing route at the expense of increased tensile strength, elongation and hardness.
Abstract: Equal-channel angular pressing (ECAP) was applied on AM90 magnesium alloy using processing route \(\hbox {B}_{\mathrm {C}}\) at \(275\,^\circ \)C up to four passes Microstructural evolution and the corresponding modification in mechanical properties (strength, elongation and hardness) corresponding to the number of ECAP passes were evaluated using X-ray diffraction (XRD), electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, tensile test and microhardness test Shear deformation was found to refine the microstructure by breaking it into smaller grains formed by dislocation reconstruction Tensile strength and hardness were found to increase by \(\sim \)128 and 23%, respectively, for ECAP-processed 2-pass sample in comparison with that of the homogenized condition After two passes, tensile strength and hardness started decreasing even though the grain size was still decreasing, which was found to be associated with texture modification during ECAP processing as observed by XRD analysis

19 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of grain refinement in AA8090 Al-Li alloy sheets during repetitive corrugation and straightening (RCS) at 300°C was studied.

7 citations

Journal ArticleDOI
Shitong Fan1, Yunlai Deng1, Yong Zhang1, Huang Xinyue1, Xinming Zhang1 
TL;DR: In this article, a novel differential temperature rolling method was adopted to overcome the challenge of inhomogeneity in thickness direction, which has hindered efforts to produce ultra-thick aluminum plates.
Abstract: Inhomogeneity in thickness direction has hindered efforts to produce ultra-thick aluminum plates. To overcome the challenge, we adopted a novel differential temperature rolling method by controllin...

5 citations

References
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Journal ArticleDOI
TL;DR: A brief overview of the available SPD technologies is given in this paper, along with a summary of unusual mechanical, physical and other properties achievable by SPD processing, as well as the challenges this research is facing, some of them generic and some specific to the nanoSPD area.

1,451 citations


"A Process of Notch Wavy Rolling for..." refers background or methods in this paper

  • ...Some of the widely used SPD techniques are equal channel angular extrusion (ECAE) or pressing (ECAP) [1, 2], accumulative roll bonding (ARB) [11], repetitive corrugating and straightening (RCS) [12], high-pressure torsion (HPT) [1, 2], and constrained groove pressing (CGP) [13, 14]....

    [...]

  • ...For example, the ECAP and RCS processes are mostly suitable for round and square bars, the ARB and CGP processes are suitable for plate-shaped materials, and the HPT process is suitable for disk-type samples....

    [...]

  • ...Strengthening by alloying is very popular, but it is much more expensive than simple mechanical strengthening techniques [1, 2, 6]....

    [...]

  • ...Therefore, different kinds of severe plastic deformation (SPD) techniques have evolved for varying the size and shape of the industrial bulk products [1, 2]....

    [...]

  • ...All these techniques, except ARB and HPT processes, are based on bending followed by straightening operations....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors defined severe plastic deformation (SPD) as metal forming processes in which a very large plastic strain is imposed on a bulk process in order to make an ultra-fine grained metal.
Abstract: Processes of severe plastic deformation (SPD) are defined as metal forming processes in which a very large plastic strain is imposed on a bulk process in order to make an ultra-fine grained metal The objective of the SPD processes for creating ultra-fine grained metal is to produce lightweight parts by using high strength metal for the safety and reliability of micro-parts and for environmental harmony In this keynote paper, the fabrication process of equal channel angular pressing (ECAP), accumulative roll-bonding (ARB), high pressure torsion (HPT), and others are introduced, and the properties of metals processed by the SPD processes are shown Moreover, the combined processes developed recently are also explained Finally, the applications of the ultra-fine grained (UFG) metals are discussed

849 citations


"A Process of Notch Wavy Rolling for..." refers background or methods in this paper

  • ...Some of the widely used SPD techniques are equal channel angular extrusion (ECAE) or pressing (ECAP) [1, 2], accumulative roll bonding (ARB) [11], repetitive corrugating and straightening (RCS) [12], high-pressure torsion (HPT) [1, 2], and constrained groove pressing (CGP) [13, 14]....

    [...]

  • ...For example, the ECAP and RCS processes are mostly suitable for round and square bars, the ARB and CGP processes are suitable for plate-shaped materials, and the HPT process is suitable for disk-type samples....

    [...]

  • ...Strengthening by alloying is very popular, but it is much more expensive than simple mechanical strengthening techniques [1, 2, 6]....

    [...]

  • ...Therefore, different kinds of severe plastic deformation (SPD) techniques have evolved for varying the size and shape of the industrial bulk products [1, 2]....

    [...]

  • ...All these techniques, except ARB and HPT processes, are based on bending followed by straightening operations....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the effects of external stress and stacking fault energies (SFE) on the width of the stacking faults were analyzed and an excellent correlation between the calculations and actual microstructures examined by scanning electron microscopy was found.

678 citations


"A Process of Notch Wavy Rolling for..." refers background in this paper

  • ...[21], the slip may be initiated with motion of the {111} plane in the {111} <110> slip system in fcc austenitic steels....

    [...]

  • ...2(b) and (c) may basically contain strain induced e- and a- martensite phases [21, 22]....

    [...]

  • ...The strained regime in austenite phase might contain substructures along deformation twins and shear bands [21], as a step toward transforming into strain-induced martensite (SIM) phase [22]....

    [...]

  • ...Since SIM is attributed to the low stacking fault energy (SFE) of the austenite phase [5, 21], the strained regimes in Fig....

    [...]

  • ...Sometimes, such overlapping may also take place on other successive and alternate or random slip planes when the slip interacts with stacking faults [21, 22]....

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Journal ArticleDOI
TL;DR: The microstructure characteristics and deformation behavior of 304L stainless steel during tensile deformation at two different strain rates have been investigated by means of interrupted tensile tests, electron-backscatter-diffraction and transmission electron microscopy (TEM) techniques as discussed by the authors.
Abstract: The microstructure characteristics and deformation behavior of 304L stainless steel during tensile deformation at two different strain rates have been investigated by means of interrupted tensile tests, electron-backscatter-diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The volume fractions of transformed martensite and deformation twins at different stages of the deformation process were measured using X-ray diffraction method and TEM observations. It is found that the volume fraction of martensite monotonically increases with increasing strain but decreases with increasing strain rate. On the other hand, the volume fraction of twins increases with increasing strain for strain level less than 57%. Beyond that, the volume fraction of twins decreases with increasing strain. Careful TEM observations show that stacking faults (SFs) and twins preferentially occur before the nucleation of martensite. Meanwhile, both ɛ-martensite and α′-martensite are observed in the deformation microstructures, indicating the co-existence of stress-induced-transformation and strain-induced-transformation. We also discussed the effects of twinning and martensite transformation on work-hardening as well as the relationship between stacking faults, twinning and martensite transformation.

389 citations


"A Process of Notch Wavy Rolling for..." refers background in this paper

  • ...The strained regime in austenite phase might contain substructures along deformation twins and shear bands [21], as a step toward transforming into strain-induced martensite (SIM) phase [22]....

    [...]

  • ...2(b) and (c) may basically contain strain induced e- and a- martensite phases [21, 22]....

    [...]

  • ...Sometimes, such overlapping may also take place on other successive and alternate or random slip planes when the slip interacts with stacking faults [21, 22]....

    [...]

  • ...The change in the individual austenitic grain before and after SNWR process reveals that the mill-annealed austenitic grain does not have strain effect regime and other features of demerits caused by high dislocation density, slip lines, twins, and shear bands [5, 21, 22], except a part of grain boundary appearing in Fig....

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