Incomplete bainite transformation in Fe-Si-C alloys

Wu, Hao; Miyamoto, Gorō; Yang, Zhigang; Zhang, Chao; Chen, H.; Furuhara, Tadashi

doi:10.1016/j.actamat.2017.05.017

Cited by 55 publications

(36 citation statements)

References 32 publications

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“…Bainite transformation is an incomplete transformation. [26][27][28] The volume fraction of bainite transformation can be determined by the microscopic observation using the method proposed in Ref. 29) or the dilatation method.…”

Section: Thermal Simulation Experimentsmentioning

confidence: 99%

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Transformation Behavior of Bainite during Two-step Isothermal Process in an Ultrafine Bainite Steel

Tian

Jiang

et al. 2018

ISIJ International

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Section: Thermal Simulation Experimentsmentioning

confidence: 99%

“…As mentioned above, bainite transformation shows incomplete transformation phenomenon due to T 0 limit. [26][27][28] Therefore, although bainite transformation basically stops after about 4 min at 430°C, it doesn't mean that all austenite are transformed into bainite.…”

Section: One-step Bainite Transformationmentioning

confidence: 99%

Transformation Behavior of Bainite during Two-step Isothermal Process in an Ultrafine Bainite Steel

Tian

Jiang

et al. 2018

ISIJ International

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“…The residual austenite is untransformed austenite after bainite transformation at 350 °C before cooling, and the RA is the austenite that is retained after cooling to room temperature. Martensite transformation is displacive transformation, and no diffusion of carbon happens during martensite transformation . Thus, the carbon content in RA at room temperature is equal to that in residual austenite at 350 °C.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Stress on Bainite Transformation, Microstructure, and Properties of a Low‐Carbon Bainitic Steel

Liu

Tian

et al. 2019

steel research int.

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The effects of applying external stress on bainite transformation, microstructure, and mechanical properties are investigated by metallography, dilatometry, etc. Results show that compressive stress during bainite transformation accelerates the bainite transformation and increases the final bainite amount due to the additional mechanical driving force. The lath‐like bainite becomes shorter, and smaller blocky martensite/austenite islands form under stress during the bainite reaction. Different from the results with stress during bainite transformation, applying stress after bainite transformation during isothermal holding cannot increase the volume fraction of bainite, and no obvious change in bainite morphology is observed. In addition, the subsequent martensite transformation is promoted during the cooling process. Moreover, the less amount of retained austenite (RA) but more carbon content in RA is obtained with applying stress after the bainite reaction. Finally, the tensile strength increases, while the elongation decreases when the external stress is imposed after bainite transformation.

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“…The composition of the X100 pipeline steel plate with a thickness of 12.8 mm that conformed to the API-5L standard is shown in Table 1. The production of X100 pipeline steel is based on alloying technology and the thermomechanical control process (TMCP), which compensates for the loss of strength caused by the reduction of the carbon content from adding alloying elements and improves the comprehensive properties of the steel via alloy phase-transformation strengthening, precipitation strengthening, and fine-grain strengthening [24][25][26]. The original microstructure of the X100 pipeline steel is mainly bainite, including granular bainite (GB), acicular ferrite (AF), and martensite-austenite (M-A) constituent.…”

Section: Experimental Materialsmentioning

confidence: 99%

“…Transformed martensite is also the location of microcracks [27,28]. Therefore, controlling the shape and distribution of the M-A constituent in laser-welded joints of X100 pipeline steel is important [25,27,29,30]. Table 1.…”

Section: Experimental Materialsmentioning

confidence: 99%

Quantitative Correlation between Thermal Cycling and the Microstructures of X100 Pipeline Steel Laser-Welded Joints

Wang

Wang²,

Yin

et al. 2019

Materials

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Due to the limitations of the energy density and penetration ability of arc welding technology for long-distance pipelines, the deterioration of the microstructures in the coarse-grained heat-affected zone (HAZ) in welded joints in large-diameter, thick-walled pipeline steel leads to insufficient strength and toughness in these joints, which strongly affect the service reliability and durability of oil and gas pipelines. Therefore, high-energy-beam welding is introduced for pipeline steel welding to reduce pipeline construction costs and improve the efficiency and safety of oil and gas transportation. In the present work, two pieces of X100 pipeline steel plates with thicknesses of 12.8 mm were welded by a high-power robot laser-welding platform. The quantitative correlation between thermal cycling and the microstructure of the welded joint was studied using numerical simulation of the welding temperature field, optical microscopy (OM), and scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). The results show that the heat-source model of a Gaussian-distributed rotating body and the austenitization degree parameters are highly accurate in simulating the welding temperature field and characterizing the austenitization degree. The effects of austenitization are more significant than those of the cooling rate on the final microstructures of the laser-welded joint. The microstructure of the X100 pipeline steel in the HAZ is mainly composed of acicular ferrite (AF), granular bainite (GB), and bainitic ferrite (BF). However, small amounts of lath martensite (LM), upper bainite (UB), and the bulk microstructure are found in the columnar zone of the weld. The aim of this paper is to provide scientific guidance and a reference for the simulation of the temperature field during high-energy-beam laser welding and to study and formulate the laser-welding process for X100 pipeline steel.

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Incomplete bainite transformation in Fe-Si-C alloys

Cited by 55 publications

References 32 publications

Transformation Behavior of Bainite during Two-step Isothermal Process in an Ultrafine Bainite Steel

Transformation Behavior of Bainite during Two-step Isothermal Process in an Ultrafine Bainite Steel

The Effect of Stress on Bainite Transformation, Microstructure, and Properties of a Low‐Carbon Bainitic Steel

Quantitative Correlation between Thermal Cycling and the Microstructures of X100 Pipeline Steel Laser-Welded Joints

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