Effect of volume fraction of bainite on microstructure and mechanical properties of X80 pipeline steel with excellent deformability

Zhang, Xiaoyong; Hui-lin, Gao; Zhang, Xueqin; Yang, Yan

doi:10.1016/j.msea.2011.10.035

Cited by 54 publications

(24 citation statements)

References 5 publications

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“…It is well known that strength and ductility of dual‐phase steels are affected by the volume fraction, grain size, shape, and distribution of hard and soft phases. [ 7 ] Therefore, increased soft phase (PF) in steel B results in lower yield strength and tensile strength but higher total elongation. Strengthening mechanisms of AF are mainly dislocation and fine grain strengthening, which are thought to increase yield strength more than tensile strength, leading to a high yield ratio of pipeline steels with AF‐dominated microstructure.…”

Section: Discussionmentioning

confidence: 99%

“…[ 6 ] It is generally acknowledged that pipeline steels with PF and AF/BF meet the requirements of excellent deformability and have a good combination of strength and toughness. [ 7–9 ] Thermomechanical controlled processing (TMCP) is an effective technique to fabricate high strength pipeline steels. The cooling rate and final cooling temperature are crucial factors affecting microstructure and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

“…At present, pipeline steels are usually low‐carbon Nb‐microalloyed steels, adding Ti and V separately or in combination. [ 1–5,7–9 ] Although satisfactory strength–toughness combination is obtained, the shape control of Nb‐microalloyed pipeline steels is difficult because of high cooling rate and low final cooling temperature, resulting in low rate of finished products.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure, Mechanical Properties, and Strain‐Hardening Behavior of V–N Microalloyed Pipeline Steels Consisted of Polygonal Ferrite and Acicular Ferrite

Wang

Gao

Cheng-lin

et al. 2020

steel research int.

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A novel V–N microalloying method is adopted to produce pipeline steels using a two‐stage thermomechanical controlled processing involving relaxation process and accelerated cooling. The main objective of the current work is to study the novel practice in terms of microstructure, mechanical properties, and strain‐hardening behavior. The microstructure of the experimental steels consists of polygonal ferrite (PF), quasi‐polygonal ferrite (QF), acicular ferrite (AF), and granular bainite (GB). Mechanical properties including strength, ductility, and low‐temperature toughness of V–N microalloyed steels meet the requirements of X80 pipeline steels. Yield strength, tensile strength, total elongation, and −20 °C impact energy are 639 MPa, 761 MPa, 21.0%, and 283 J when the volume fraction of PF is 9.1%, and 603 MPa, 724 MPa, 24.1%, and 214 J when the volume fraction of PF increases to 30.4%. The V–N microalloyed steels exhibit high strain‐hardening ability, and the values of strain‐hardening exponent are 0.12 and 0.11 based on Hollomon analysis.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructure, Mechanical Properties, and Strain‐Hardening Behavior of V–N Microalloyed Pipeline Steels Consisted of Polygonal Ferrite and Acicular Ferrite

Wang

Gao

Cheng-lin

et al. 2020

steel research int.

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“…Dual-phase (DP) steel, a type of advanced high-strength steel (AHSS), is being increasingly used in the transportation of oil and natural gas due to its good processability and balanced combination of strength and ductility [1,2,3]. This excellent performance is attributed to dual-phase microstructural characteristics.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Microstructures and Fatigue Properties for Dual-Phase Pipeline Steels by Gleeble Simulation of Heat-Affected Zone

Zhao

Cheng

et al. 2019

Materials

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To increase transmission efficiency and reduce operation cost, dual-phase (DP) steels have been considered for pipeline applications. Welding has to be involved in such applications, which would cause a localized alteration of materials and cause many potential fatigue issues to arise under cyclic loading. In this work, the fatigue crack propagation and fatigue life of simulated heat-affected zone (HAZ) were examined. Results indicate that when the maximum stress is at the same magnitude, the fatigue life at a peak temperature of 1050 °C is very close to that of a peak temperature of 850 °C, and both of them are higher than that of a peak temperature of 1350 °C. The changes in da/dN with ΔK for HAZ subregions are attributed to the variation of crack path and fracture mode during the crack propagation. The fatigue cracks may propagate along the bainite lath preferentially in coarse-grained HAZ (CGHAZ), and the prior austenite grain boundaries can change the crack growth direction. A considerable amount of highly misoriented grain boundaries in fine-grained HAZ (FGHAZ) and intercritical-grained HAZ (ICHAZ) increase the crack growth resistance. The difference of fatigue crack propagation behavior in HAZ subregions between actual and simulated welded joints was also discussed.

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“…Secondary refining and continuous casting followed by thermo-mechanical controlled processing (TMCP) with strict temperature-reduction route and post-deformation cooling rate control are used to produce X80 and a higher grade pipes with ultrafine ferrite-bainite (fully bainite) structure. The X80 grade steels were found to exhibit good combination of strength, high plasticity and toughness [4][5].…”

Section: Introductionmentioning

confidence: 99%

Luders Deformation Mechanisms on Yield Point in X80 Grade Pipeline with Ultrafine Structure

Polukhina¹,

Вичужанин²,

Хотинов³

et al. 2019

KEG

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Effect of volume fraction of bainite on microstructure and mechanical properties of X80 pipeline steel with excellent deformability

Cited by 54 publications

References 5 publications

Microstructure, Mechanical Properties, and Strain‐Hardening Behavior of V–N Microalloyed Pipeline Steels Consisted of Polygonal Ferrite and Acicular Ferrite

Microstructure, Mechanical Properties, and Strain‐Hardening Behavior of V–N Microalloyed Pipeline Steels Consisted of Polygonal Ferrite and Acicular Ferrite

Characterization of Microstructures and Fatigue Properties for Dual-Phase Pipeline Steels by Gleeble Simulation of Heat-Affected Zone

Luders Deformation Mechanisms on Yield Point in X80 Grade Pipeline with Ultrafine Structure

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