Formation Mechanism of Dislocation Walls during Cyclic Deformation in an Fe–Si Alloy

Shuto, Hiroshi; Tanaka, Yasuaki; Miyazawa, Tomotaka; Arai, Shigeo; Fujii, Toshiyuki

doi:10.2355/isijinternational.isijint-2019-314

Cited by 4 publications

(1 citation statement)

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“…And the dislocation structure is maze and cell structures under the higher strain amplitude. Shuto H et al [15] studied the causes of the formation of dislocation walls, found that the dislocation slides along a single slip surface at the initial stage of deformation, the activation of other slip systems leads to the "wall" shape of the dislocation structure. Tsai Y T et al [16] studied the fatigue behavior and dislocation structure of SAF2507 alloy, found that the alloy is hardened rstly and then softened under the cyclic loading.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Soft/Hardening and Microscopic Mechanism of GS-20Mn5

Zou

Liu

Han

et al. 2021

Preprint

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The cyclic plastic characteristics of metal materials are different from the deformation characteristics under monotonic loading, which has an important effect on the safety of structures in service under cyclic loading. However, GS-20Mn5, which is commonly used in large hydraulic machine beams, offshore platforms and large Bridges, is still lacking the studies of mechanical response characteristics under cyclic loading. In this study, the cyclic softening/hardening characteristics of GS-20Mn5 are studied by a series of cyclic loading tests under uniaxial strain control. Combined with transmission electron microscope (TEM) analysis of cyclic loading tests under typical strain levels, the microscopic mechanism of cyclic softening/hardening is discussed. The results show that the cyclic softening/hardening properties of GS-20Mn5 cast steel are sensitive to amplitudes and cycles. At smaller strain amplitudes (0.16%,0.2% and 0.3%), the cyclic hardening properties of GS-20Mn5 cast steel are rapid at the beginning of the cycle, followed by cyclic softening and then slow secondary cyclic hardening at the end. However, under larger strain amplitudes (0.4% and 0.5%), the cyclic hardening continues during the cyclic loading, and the hardening rate is bigger at the beginning of the cyclic loading and smaller at the later cyclic stage. The cyclic softening/hardening characteristics of GS-20Mn5 cast steel are related to the dislocation structure of ferrite and pearlite. Taking the strain amplitude of 0.2% as an example, the initial cyclic hardening is mainly caused by the proliferation and interaction of dislocations in ferrite. Dislocation spots and cell walls in ferrite grains are mainly caused cyclic softening at the initial stage, the secondary cyclic hardening is directly related to dislocation proliferation and entanglement in pearlite.

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Section: Introductionmentioning

confidence: 99%