Microstructure and mechanical properties of IF steel deformed during plane stress local torsion

Shamdani, Amir Hossein; Khoddam, Shahin; Thomson, Peter Frederic; Dehghan-Manshadi, Ali

doi:10.1007/s10853-011-6121-4

Cited by 12 publications

(7 citation statements)

References 17 publications

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“…The implementation method is explained in detail elsewhere. 22 During the local torsion process, the history of torque which is needed to twist the specimen through a specified twist angle can be recorded during experiments and the numerical simulation as well. In order to make sure that the results of the finite element simulations for the local torsion are reliable, the numerical and experimental torque-twist curves were compared as illustrated in Fig.…”

Section: Analysis Of Local Torsionmentioning

confidence: 99%

“…Although this is not the case with the local torsion process, however the advantages of grain refinement from the local torsion in improving the mechanical strength of the material around the hole surface has already been established. 22 The usefulness of the local torsion with or without the cold expansion cannot be solely assessed based on its capability in producing compressive residual stresses. The investigation has to include the interaction of grain refinement and the residual stress on the overall performance of a fastener hole subjected to the CELT.…”

Section: Residual Stress On Mid-thickness Planementioning

confidence: 99%

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A comparative numerical study of combined cold expansion and local torsion on fastener holes

Shamdani

Khoddam

2012

Fatigue Fract Eng Mat Struct

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A B S T R A C T Cold expansion and local torsion processes provide controllable strengthening mechanisms for a fastener hole and therefore have engineering significance. They rely on the residual stress and the accumulated shearing strain, respectively, which are difficult to measure. Due to the complex closed form solutions for these mechanisms, their numerical study is of great importance. In this work, a combination of the cold expansion and the local torsion on a fastener hole has been investigated numerically to evaluate the amount and nature of the total accumulated residual stresses around a fastener hole. Different cases of the cold expansion and the local torsion processes were modelled and studied by finite element simulation to investigate the existence of a loading case which produces a beneficial compressive residual stress field in the vicinity of a hole. Sensitivity of the final residual stress with respect to a range of process parameters including adequate diametral interference and angle of rotation was investigated.Keywords elastic-plastic behaviour; finite element analysis; hole expansion technique; plastic strain localization; residual stress; torsion. N O M E N C L A T U R Eb = Rate at which size of yield surface changes C k = Initial kinematic hardening modulus d f = Final hole diameter d i = Initial hole diameter r = Radial distance, radial coordinate r i = Hole radius Q ∞ = Maximum change in size of yield surface z = Longitudinal coordinate a k = Back-stress (kinematic shift) y k = Rate at which kinematic hardening modulus changes ε pl = Equivalent plastic strain θ = Tangential coordinate ξ = Degree of cold expansion σ | 0 . = Size of yield surface at zero plastic strain σ 0 = Size of yield surface = Twist angle I N T R O D U C T I O NCreating stronger and tougher materials is a perpetual goal of design and materials engineers. Mechanical joints such as bolts and rivets, that require the use of drilled holes, are extensively used in mechanical structures. These joints are inherently vulnerable to failure due to stress Correspondence: S. Khoddam.

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Section: Analysis Of Local Torsionmentioning

confidence: 99%

Section: Residual Stress On Mid-thickness Planementioning

confidence: 99%

A comparative numerical study of combined cold expansion and local torsion on fastener holes

Shamdani

Khoddam

2012

Fatigue Fract Eng Mat Struct

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“…However, the UFG microstructure brought about limited ductility with a few percent uniform elongation that limits its applications ( Ref 23). Previous reports have shown that the ductility of UFG materials can be enhanced without compromising the strength by appropriate annealing treatments after SPD (Ref [22][23][24][25].This improvement was attributed to the bimodal grain size distribution introduced into the deformed microstructure with the combination of fine and coarse grains (Ref [25][26][27][28][29]. Review of UFG low carbon steel suggests that both high strength and ductility can be achieved by combining a few percentage of micron-sized (1-10 lm) grains in UFG matrix (Ref 4).…”

Section: Introductionmentioning

confidence: 98%

Bulk Ultrafine-Grained Interstitial-Free Steel Processed by Equal-Channel Angular Pressing Followed by Flash Annealing

Verma

Pandey

Bansal

et al. 2016

J. of Materi Eng and Perform

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Interstitial-free steel workpieces are deformed by equal-channel angular pressing (ECAP) for equivalent strain e vm = 3 and e vm = 21 followed by flash annealing. Microstructures are analyzed by optical microscopy, scanning electron microscopy and transmission electron microscopy. Mechanical properties are evaluated by hardness testing. Yield strength of materials is calculated from hardness values. Flash annealing (at 675°C) of ECAPed samples for e vm = 3 and e vm = 21 results in abnormal subgrain growth and abnormal grain growth, respectively. Flash annealing at 700°C of ECAPed (at e vm = 3) IF steel converts abnormally grown subgrains to grains which serve as nuclei for recrystallization and that result in bimodal grain size distribution. Bimodal grain size distribution is also produced when ECAPed IF steel for e vm = 21 is flash annealed at 675°C due to abnormal grain growth or secondary recrystallization. Flash annealing of IF steel samples ECAPed for low e vm , in the temperature range 600-675°C, decreases the hardness continuously with increase in the annealing temperature but it increases at high e vm. The former is due to annihilation of defects but the later is caused by ordering of nonequilibrium boundaries. The hardening and strengthening behaviors are similar.

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“…Nowadays, SPD is highly desirable for the application and increasingly introduces pure shear and simple shear in the deformation process . Conventional SPD methods, such as equal channel angular press (ECAP) and twist extrusion (TE), have been introduced to achieve the local grain refinement or bulk grain refinement to strengthen the materials. However, they have a relatively high requirement for the deformation dye and equipment, especially for the high yield strength materials to realize SPD difficultly, such as steel, whose yield strength is almost 1300 MPa.…”

Section: Introductionmentioning

confidence: 99%

Effect of Different Torsion Routes on Microstructure Evolution and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel Undergoing Deformation‐Induced Phase Transformation

Wang

Zhu

et al. 2019

steel research int.

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The microstructure evolution and mechanical properties of the 0Cr12Mn5Ni4Mo3Al steel subjected to single direction torsion (SDT) and torsion‐reverse torsion (TRT) are investigated. The finite‐element method (FEM) is used to obtain the value of the equivalent strain in different torsion routes. These results demonstrate that the size of the grain becomes more refined when undergoing SDT and TRT. With a decrease in the TRT angle, the distribution of α‐phase appears like a kinked curve, and the grain refinement becomes less and less obvious. In addition, deformation‐induced phase transformation emerges and results in ferrite and austenite concurrent rearrangements. Furthermore, the material hardening is mainly due to the increase in statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) with the accumulation of the equivalent strain and the strain gradient. Finally, the fracture mechanism is also discussed to reveal the strength ductility of the samples.

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Microstructure and mechanical properties of IF steel deformed during plane stress local torsion

Cited by 12 publications

References 17 publications

A comparative numerical study of combined cold expansion and local torsion on fastener holes

A comparative numerical study of combined cold expansion and local torsion on fastener holes

Bulk Ultrafine-Grained Interstitial-Free Steel Processed by Equal-Channel Angular Pressing Followed by Flash Annealing

Effect of Different Torsion Routes on Microstructure Evolution and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel Undergoing Deformation‐Induced Phase Transformation

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