Thermo-mechanical treatment effects on stress relaxation and hydrogen embrittlement of cold-drawn eutectoid steels

Caballero, L.; Atienza, J. M.; Calafat, Manuel Elices

doi:10.1007/s12540-011-6006-8

Cited by 13 publications

(6 citation statements)

References 43 publications

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“…The production process included the following technological operations: stabilization, surface preparation for drawing, multistage cold drawing, stranding, straightening, mechanicalthermal treatment. Since the wire drawing technology involves high strain degrees ~88-90%, this process will inevitably lead to the residual stresses generation that directly affect both the mechanical and exploitation properties of the future PSC strand, and the stability of the process of stranding [13][14][15][16][17][18][19][20]. For this reason, the analysis of the technological process should be based on the assessment of the absolute values and distribution of residual stresses that make the most significant contribution to the stress-strain state of PSC strand.…”

Section: Methodsmentioning

confidence: 99%

“…The main property-forming parameters in this case are the steel microstructure and internal stresses, which determine the final level of strength and relaxation resistance. If the microstructure formation is relatively simple using experimental and laboratory studies [13], then the prediction of residual stresses level in multioperational technologies is optimally performed using computer simulation methods.…”

Section: Introductionmentioning

confidence: 99%

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FEM research of internal stresses evolution in the prestressing strand production

Korhunov

Medvedeva

Ivekeeva

et al. 2020

METAL 2020 Conference Proeedings

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The article presents the finite-element modeling results of stranding, reduction, straightening and mechanicalthermal treatment (MTT) of prestressing strand (PSC strand). Computer models took into account the distribution of residual stresses formed at the preliminary stage of wire drawing. During the simulation, the effect of MTT on the internal stresses of the wires was studied: residual stresses after the drawing process and additional stresses after the stranding. All studied methods demonstrated a positive effect not only from the point of eliminating internal stresses, but also from the point of view of their favorable redistribution. The reduction of PSC strand in a monolith tool with strain degree 1-3% allows to minimize tensile stresses on the surface of the wires and save compressive stresses in the center of the wires. The straightening by a group of 5 rolls made it possible to reduce the tension of outer wires twice. The MTT application, combining the effects of various physical nature, made it possible to control over a wide range the redistribution of residual stresses in the wires after high strain degrees and the additional stresses created during the stranding, which affect the preservation of the geometric parameters of the PSC strand. The study showed that to eliminate longitudinal residual stresses, the magnitude of the tension in the MTT is the most important parameter. Therefore, with a minimum value of tension, the residual stresses are not redistributed either in the central or in the surface layers, regardless of the temperature of the MTT. However, with tension above 70 kN and a temperature of 380-400°C, the residual stresses in the center and on the surface of the wires are balanced or almost completely eliminated.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

FEM research of internal stresses evolution in the prestressing strand production

Korhunov

Medvedeva

Ivekeeva

et al. 2020

METAL 2020 Conference Proeedings

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“…As the wires for prestressing strands are normally drawn at high deformation rates reaching 88-90%, this inevitably creates residual stresses, which affect both the mechanical properties and performance of the final strand, as well as the stranding consistency [13][14][15][16][17][18][19][20]. That's why analysis of the 7-wire prestressing strand production process should be based on evaluation of absolute…”

Section: Materials and Methods Of Researchmentioning

confidence: 99%

“…They dictate the ultimate strength and relaxation resistance. If it can be relatively easy to gradually build a microstructure through successive process stages by means of experimental and laboratory studies [13], it would be better to use computer simulation software to predict the residual stresses resultant from multi-stage processes involved in the wire production.…”

Section: Introductionmentioning

confidence: 99%

FEM study of internal stresses evolution in prestressing strands

Корчунов¹,

Medvedeva²,

Ivekeeva³

et al. 2020

cisisr

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This paper describes the results of modeling when the processes of stranding, reduction, straightening and thermo-mechanical treatment (TMT) of prestressing strands were simulated with the help of finite-element method. The distribution of residual stresses used in the simulation models refers to the stresses created at the preliminary stage of wire drawing. The simulation study looked at the effect of thermo-mechanical treatment on the internal wire stresses: residual stresses resultant from the drawing process and further stranding stresses. All studied methods demonstrated a positive effect not only in terms of eliminating internal stresses, but also from the point of view of their redistribution. Reduction of a strand in a solid tool at the ratios of 1–3 % allows to create tensile stresses at the surface of the wire and retain compressive stresses in its core. Straightening in a 5-roller group helped reach a double relaxation in outer wires. TMT, a process combining different physical effects, enabled to control within a broad range the redistribution of residual stresses in steel that was subjected to prior drawing at high deformation ratios. Such residual stresses occur as a result of stranding stresses that accompany the stranding operation and can affect the geometry of the strand. The study showed that tension as a TMT parameter plays a greater role in the elimination of longitudinal residual stresses. That’s why, at the minimum tension, almost no redistribution of residual stresses occur either in the central or in the near-surface layers irrespective of the TMT temperature regime applied. However, when the tension exceeding 70 kN is applied at the temperatures of 380–400 °C, the central and surface residual stresses balance off in the wire or almost disappear. This research was carried out under the Decree No. 220 dated 9th April 2010 of the Government of the Russian Federation (Contract No. 075-15-2019-869 dated 12th May 2019) and was funded by the Russian Science Foundation (Project No. 20-69-46042 dated 20th May 2020) and by the Russian Ministry of Education and Science with the goal of developing high-tech production (contract nos. 02.G25.31.078, December 1, 2015; and MK204895, July 27, 2015).

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“…A not yet investigated problem is how residual stress states are changed in the ferrite and cementite phases in the subsequent steps of manufacturing. Past investigations concentrated only in fully pearlitic steels [3,[5][6][7]. The main drawback of about residual stress states in cementite after drawing [3,4] is the lack of knowledge from previous and subsequent steps of the cold drawing process: pre-straightening and polishing and straightening by crossed rolls respectively.…”

Section: Introductionmentioning

confidence: 99%

Residual stress states in cementite and ferrite in a combined cold drawing process of AISI 1045 steel using neutron diffraction and synchrotron radiation

Nunes¹,

Rocha²,

Hirsch³

2021

Tecnol. Metal. Mater. Min.

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The evaluation and control of residual stress states in manufacturing processes such as cold drawing can be difficult, especially in multi-phase materials. Diffraction methods are ideal for characterizing residual stresses in individual phases provided these phases scatter neutrons or X-rays well enough to obtain a good signal. Residual stresses determination problems in drawn components have been reported. Main constraints are measurements in the primary ferrite phase only. The presence of cementite in carbon steel is often neglected. A problem that has not yet been extensively investigated is how residual stresses in the ferrite and cementite phases develop in subsequent steps of material processing such as cold drawing. In this work a combined straightening and bar drawing process of AISI 1045 round bars from coils of a hot-rolled material was investigated. A careful characterization of the material, including residual stress states in the ferrite (α−Fe) and cementite (Fe 3 C) phases, using neutron diffraction and synchrotron diffraction was performed for each of the different manufacturing steps. The drawing and polishing and straightening (P.S.) parameters by crossed rolls were changed to evaluate their influence on the α−Fe and Fe 3 C residual stress distributions. After the drawing process, residual stresses in the cementite phase are highly tensile, as already reported, however it can be shown that after polishing and straightening steps residual stresses in the cementite phase decrease and residual stress distributions also depend on the tool angle used.

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Thermo-mechanical treatment effects on stress relaxation and hydrogen embrittlement of cold-drawn eutectoid steels

Cited by 13 publications

References 43 publications

FEM research of internal stresses evolution in the prestressing strand production

FEM research of internal stresses evolution in the prestressing strand production

FEM study of internal stresses evolution in prestressing strands

Residual stress states in cementite and ferrite in a combined cold drawing process of AISI 1045 steel using neutron diffraction and synchrotron radiation

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