Continuous cooling transformation behavior and impact toughness in heat-affected zone of Nb-containing fire-resistant steel

Wang, Hong Hong; Qin, Z. P.; Wan, Xiangliang; Wei, Ran; Wu, Kai; Misra, Devesh

doi:10.1007/s12540-017-6776-8

Cited by 20 publications

(6 citation statements)

References 17 publications

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“…In addition to the above effects on grain refinement and microstructure refinement, Ti and Nb also have some effects on the structure type. According to the theory of solid-state transformation [14], diffusion of C and other alloying elements exists during bainite transformation, while Ti and Nb cause a decrease in the activity of C and inhibit the diffusion of C atoms [15]. In the thermal cycle cooling stage of sample #1 without Ti and Nb, the C atoms can easily diffuse to grain boundaries to agglomerate and grow carbides or to form carbon-rich regions.…”

Section: Effect Of Ti and Nb On The Microstructure Of Cghazmentioning

confidence: 99%

Coarse Grained Heat-Affected Zone Microstructure and Brittleness of Ti-Nb-B Microalloyed High Toughness and Wear Resistant Steel

Dong

et al. 2019

Metals

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The effects of B, Ti-Nb, and Ti-Nb-B microalloying on the microstructure and properties of the coarse grain heat affected zone (CGHAZ) of C-Mn-Si-Mo wear-resistant steel have been investigated by means of thermal simulation, mechanical property test, microstructure analysis, and theoretical formula calculation. The B, Ti-Nb, and Ti-Nb-B microalloyed C-Mn-Si-Mo wear-resistant steels prepared by a controlled rolling + direct quenching + low temperature (CR + DQ + T) process have martensite/bainite (M/B) dual-phase microstructure and fully-refined effective grain size, which make the base metal to have high hardness and impact toughness. At the heat input of 20 kJ/cm, the impact toughness of CGHAZ of three kinds of microalloyed wear-resistant steels decreased in varying degrees. The main reasons for brittleness were coarse grain embrittlement and microstructural embrittlement. Ti-Nb-B microalloying can effectively prevent grain growth in CGHAZ while avoiding the formation of pearlite, small lump ferrite, and large grain carbides at the grain boundaries, thereby reducing the embrittlement of coarse grain and microstructure.

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Section: Effect Of Ti and Nb On The Microstructure Of Cghazmentioning

confidence: 99%

Coarse Grained Heat-Affected Zone Microstructure and Brittleness of Ti-Nb-B Microalloyed High Toughness and Wear Resistant Steel

Dong

et al. 2019

Metals

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“…The present linepipe steels generally consist of PF, AF, GB, BF, and martensite-austenite constituent (MA) 20 – 25 Optical and SEM micrographs of the S and T steels are shown in Fig. 1(a–f) .…”

Section: Resultsmentioning

confidence: 97%

Study of Bauschinger effect of acicular ferrite and polygonal ferrite through ex-situ interrupted bending tests in API X80 linepipe steels

Kim

Sohn

Kim

et al. 2018

Sci Rep

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Linepipe steels complexly consisted of low-temperature transformation microstructures of bainitic ferrite, granular bainite, and acicular ferrite (AF) as well as polygonal ferrite (PF) which individually affect the Bauschinger effect occurring during the pipe-forming. In this study, microscopic analyses of electron back-scattered diffraction (EBSD) coupled with tension-compression and interrupted bending tests were performed for verification of the Bauschinger effect of AF and PF working as major microstructures in single-phase- and two-phase-rolled API X80 steels, respectively. With respect to microstructural effects on Bauschinger effect, the reduction in mobile dislocation density during the flattening was smaller in the AF than in the PF. However, the dislocation pile-up at low-angle substructures and high-angle grain boundaries was more frequently observed, thereby leading to the higher back stress and Bauschinger effect in the AF. Boundary kernel average misorientation (KAM) profile played a critical role in determining the Bauschinger effect because they were closely related with the back stress. Thus, the Bauschinger effect was higher in the single-phase-rolled steel than in the two-phase-rolled steel. The present ex-situ interrupted bending methods coupled with EBSD analyses are outstanding ones for the detailed explanation of Bauschinger effect and provide an important idea for the yield strength designs of linepipe steels.

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“…Phase transformation products were greatly affected by the cooling rate. [ 34,35,59 ] At low cooling rates, QPF and P can be formed, whereas bainite and martensite appear at high cooling rates. [ 36 ] In the present work, it is found that the dominant microstructure changed from P + F, through GB to LB with the increasing cooling rate.…”

Section: Discussionmentioning

confidence: 99%

Simulated Coarse Grain Heat‐Affected Zone Transformation Behavior of Newly Developed Zr–Ti–RE Deoxidized High‐Strength Low‐Alloy Steels with Extremely High Impact Toughness

Yin

Cheng

et al. 2023

steel research int.

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Continuous cooling transformation behavior and impact toughness in heat-affected zone of Nb-containing fire-resistant steel

Cited by 20 publications

References 17 publications

Coarse Grained Heat-Affected Zone Microstructure and Brittleness of Ti-Nb-B Microalloyed High Toughness and Wear Resistant Steel

Coarse Grained Heat-Affected Zone Microstructure and Brittleness of Ti-Nb-B Microalloyed High Toughness and Wear Resistant Steel

Study of Bauschinger effect of acicular ferrite and polygonal ferrite through ex-situ interrupted bending tests in API X80 linepipe steels

Simulated Coarse Grain Heat‐Affected Zone Transformation Behavior of Newly Developed Zr–Ti–RE Deoxidized High‐Strength Low‐Alloy Steels with Extremely High Impact Toughness

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