Microstructural evolution and its influence on toughness in simulated inter-critical heat affected zone of large thickness bainitic steel

Di, Xinjie; Tong, Min; Li, Chengning; Zhao, Chen; Wang, Dongpo

doi:10.1016/j.msea.2018.11.070

Cited by 49 publications

(29 citation statements)

References 38 publications

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“…At low temperature, the BF structure exhibits different characteristics from the finely dispersed AF structure with HAGB [27]. During low-temperature impact tests, the stress concentration around a hard microstructure, such as BF, acts as a major factor in crack formation [2,5,7]. It can be seen that not only the fraction of BF, but also the fraction of AF is lower than that of T2 and B2.…”

Section: Impact Toughness Of Tmcp Steel and Saw Heat-affected Zonementioning

confidence: 96%

“…Recently, the consumption of energy resources has been increasing with the continuing development of industry. The expansion of resource development systems such as oil pipelines and offshore plants for transporting resources is accelerating [1][2][3][4][5][6][7][8][9]. Since energy resources in areas close to land have almost been exhausted, it is necessary to explore and develop in extreme environments such as the polar regions and the deep sea.…”

Section: Introductionmentioning

confidence: 99%

“…HAZ forms different structures between the base metal and the weld zone. The coarse grain heat-affected zone (CGHAZ) is the region with the worst mechanical properties [2,4,7]. Grain coarsening causes a fracture mechanism in which brittle cracks propagate due to external impact, having a direct effect on toughness degradation [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, due to the complex microstructures of steels with complex thermal history, there is a limit to clearly distinguishing images on the basis of optical microscopy (OM) and scanning electron microscopy (SEM) photography. Recently, quantitative analysis methods have been reported on the basis of various structures of low-carbon steel through electron back scatter diffraction (EBSD) analysis [2][3][4]6,10], and this study quantitatively analyzes the microstructure of the HAZ of TMCP steel using the EBSD analysis method.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

Choi

Kim

et al. 2021

Metals

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This study investigated the low-temperature fracture behavior of an 80-mm-thick low-carbon steel plate welded by submerged arc. The relationship between impact absorbed energy and ductility–brittle transition temperature (DBTT) based on the microstructures was evaluated through quantitative analysis on grain size and complex constituent phases using advanced EBSD technique. The microstructure formed differently depending on the heat affections, which determined fracture properties in a low-temperature environment. Among the various microstructures of the heat-affected zone (HAZ), acicular ferrite has the greatest resistance to low-temperature impact due to its fine interlocking formation and its high-angle grain boundaries.

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Section: Impact Toughness Of Tmcp Steel and Saw Heat-affected Zonementioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

Choi

Kim

et al. 2021

Metals

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show abstract

“…Additionally, the higher the heat input, the lower the hardness in the HAZ, leading to limited application [10]. Usually, the softening phenomenon potentially appeared in the coarse-grained zone, intercritical zone or fine-grained zone of HAZ, namely, CGHAZ, ICHAZ and FGHAZ, respectively [11][12][13]. Gu et al [14] suggested that the larger-size polygonal ferrite (PF) and granular ferrite formed from the ununiform prior austenite resulted in softening phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb Addition and Heat Input on Heat-Affected Zone Softening in High-Strength Low-Alloy Steel

et al. 2022

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The effect of both Nb content and heat input on the softening phenomenon of the heat-affected zone (HAZ) of low-alloy high-strength steel was studied through welding thermal simulation experiments. The microstructure evolution, density variation of geometrically necessary dislocation, microhardness distribution and the second phase precipitation behavior in HAZ was characterized and analyzed by combining the optical microscope, scanning electron microscope, high-resolution transmission electron microscope with microhardness tests. The results showed that the softening appeared in the fine-grain HAZ (FGHAZ) of the low-alloy high-strength steel with the polygonal ferrite and bainite microstructure. With an increase in Nb content, the FGHAZ softening was inhibited even with high heat input; however, the hardness shows little variation. On the one hand, the increase in the Nb content increased the volume fraction of high-strength bainite in the FGHAZ. On the other hand, the remarkable strengthening was produced by the equally distributed precipitation nanoparticles. As a result, the two factors were the main reason for the solution of the FGHAZ softening problem in the low-alloyed high-strength steel with the mixed microstructure of ferrite and bainite.

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Effect of Microstructural Evolution on the Mechanical Properties of Intercritical Heat‐Affected Zone of Quenched‐and‐Tempered Ultrahigh‐Strength Steel

Zhang

Wen

et al. 2022

steel research int.

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In order to investigate the effect of microstructural evolution on the mechanical properties in the intercritical heat-affected zone (ICHAZ) of the quenched-andtempered ultrahigh-strength steel, the simulated ICHAZ samples with different austenite transformation degrees (0%, 25%, 50%, 75%, and 100%) are prepared. These samples are named IC-0%, IC-25%, IC-50%, IC-75%, and IC-100%, respectively. The fine-grained fresh martensite (FM) is produced in the partial austenite transformation during cooling. The austenite in IC-100% with the lowest C and Mn content is transformed into a mixture of FM and granular bainite (GB). The IC-0% and the IC-25% are softened by about 20 HV 10 compared with that of the base metal. When the matrix is transformed into quasi-polygonal ferrite (QPF), the large difference in microhardness between FM and QPF causes the instability of their interfaces, resulting in the deterioration of the impact toughness in IC-50% and IC-75%. However, from IC-75% to IC-100%, the impact toughness has been improved from 18.0 to 28.9 J. In addition to the less embrittlement of microstructure in IC-100%, the lower microhardness difference between FM and GB is the main reason.

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Microstructural evolution and its influence on toughness in simulated inter-critical heat affected zone of large thickness bainitic steel

Cited by 49 publications

References 38 publications

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

Effect of Nb Addition and Heat Input on Heat-Affected Zone Softening in High-Strength Low-Alloy Steel

Effect of Microstructural Evolution on the Mechanical Properties of Intercritical Heat‐Affected Zone of Quenched‐and‐Tempered Ultrahigh‐Strength Steel

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