Back stress strengthening and strain hardening in gradient structure

Yang, Meng; Pan, Yue; Yuan, Fuping; Zhu, Yuntian; Wu, Xiaolei

doi:10.1080/21663831.2016.1153004

Cited by 963 publications

(220 citation statements)

References 37 publications

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“…These strain gradients produce geometrically necessary dislocations and increase both the yield strength and strain hardening [29,34,57]. It has been reported that mechanical incompatibility will also cause high back stress and back stress hardening [35,58]. Detailed investigations are being carried out to study this issue.…”

Section: Dynamic Strain Partitioningmentioning

confidence: 99%

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Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

et al. 2016

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a b s t r a c tWe report a design strategy to combine the benefits from both gradient structure and transformationinduced plasticity (TRIP). The resultant TRIP-gradient steel takes advantage of both mechanisms, allowing strain hardening to last to a larger plastic strain. 304 stainless steel sheets were treated by surface mechanical attrition to synthesize gradient structure with a central coarse-grained layer sandwiched between two grain-size gradient layers. The gradient layer is composed of submicron-sized parallelepiped austenite domains separated by intersecting ε-martensite plates, with increasing domain size along the depth. Significant microhardness heterogeneity exists not only macroscopically between the soft coarse-grained core and the hard gradient layers, but also microscopically between the austenite domain and ε-martensite walls. During tensile testing, the gradient structure causes strain partitioning, which evolves with applied strain, and lasts to large strains. The g / a 0 martensitic transformation is triggered successively with an increase of the applied strain and flow stress. Importantly, the gradient structure prolongs the TRIP effect to large plastic strains. As a result, the gradient structure in the 304 stainless steel provides a new route towards a good combination of high strength and ductility, via the co-operation of both the dynamic strain partitioning and TRIP effect.

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Section: Dynamic Strain Partitioningmentioning

confidence: 99%

“…This is due to the macroscopic strength gradient and mechanical incompatibility between layers [29e34]. Such a mechanical incompatibility was also found to produce high back stress, which may contribute to both strength and ductility [3,35].…”

Section: Introductionmentioning

confidence: 99%

Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

et al. 2016

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“…In our previous paper [21], such a transient deformation stage has been found to be caused by the back stress hardening due to the deformation incompatibility between different phases over a strain regime corresponding to the elasto-plastic transition stage. Similar behavior in the hardening rate has also been found recently in the other heterogeneous materials, such as gradient structure [57,58], heterogeneous lamella structure [59] and multilayer laminates [60]. During the plastic deformation of this HSSS, load transfer and strain partitioning between two phases will occur since the softer fcc austenite phase are easier to deform than the harder B2 phase.…”

Section: Resultsmentioning

confidence: 56%

Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

Wang

Yang

et al. 2017

Metals

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Abstract:The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound) is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness.

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“…Some researchers have found that gradient distribution of stress near the interface significantly contributes to working hardening in multi-layered metals. Yang et al [11] proposed that a strain gradient and back stress strengthening caused by the pileup of GNDs played a critical role in the observed high stress and high strain hardening. Therefore, it is promising that multi-layered metals with heterogeneous structure may yield a good combination of strength and ductility by combining both bimodal structure and interface effects.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous multi-layered IF steel with simultaneous high strength and good ductility

Zhang

Jiang

Wang

et al. 2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Multi-layered IF steel samples were designed and fabricated by hot compression followed by cold forging of an alternating stack of cold-rolled and annealed IF steel sheets, with an aim to improve the strength of the material without losing much ductility. A very good combination of strength and ductility was achieved by proper annealing after deformation. Microstructural analysis by electron back-scatter diffraction revealed that the good combination of strength and ductility is related to a characteristic hierarchical structure that is characterized by layered and lamella structures with different length scales.

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Back stress strengthening and strain hardening in gradient structure

Cited by 963 publications

References 37 publications

Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility

Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

Heterogeneous multi-layered IF steel with simultaneous high strength and good ductility

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