<i>In situ</i> observation and electron backscattered diffraction analysis of granular bainite in simulated heat-affected zone of high-strength low-alloy steel

Peng, Kang; Yang, Chunli; Fan, Chenglei; Lin, Sanbao

doi:10.1080/13621718.2017.1351777

Cited by 9 publications

(4 citation statements)

References 24 publications

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“…With the increase in heat input, lath bainite decreases, and the granular bainite increases because the for mation temperature of granular bainite is marginally higher. Due to the increase in hea input, the residence time of austenite in the high-temperature stage is prolonged, and granular bainite is developed at higher temperatures [17], leading to the inconspicuous lath characteristics. Figure 3 shows the statistical results of the original austenite grain size under differ ent heat input conditions.…”

Section: Microstructure Of Welding Heat Affected Zonementioning

confidence: 99%

“…The grain boundary orientation distribution of samples with the heat input of 150 kJ/cm and 300 kJ/cm is shown in Figure 4. Orientation difference greater than 15 • is defined as a large angle grain boundary, and 2 • -15 • is defined as the low angle grain boundary [17]. In the figure, the black line is a high-angle grain boundary, and the green line stands for a small-angle grain boundary.…”

Section: Microstructure Of Welding Heat Affected Zonementioning

confidence: 99%

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The Influence of the Second Phase on the Microstructure Evolution of the Welding Heat-Affected Zone of Q690 Steel with High Heat Input

Qi,

Pang,

et al. 2024

Materials

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Q690 steel is widely used as building steel due to its excellent performance. In this paper, the microstructure evolution of the heat-affected zone of Q690 steel under simulated high heat input welding conditions was investigated. The results show that under the heat input of 150–300 kJ/cm, the microstructures of the heat-affected zone are lath bainite and granular bainite. The content of lath bainite gradually decreased with the increase in heat input, while the content of granular bainite steadily increased. The proportion of large-angle grain boundaries decreased from 51.1% to 40.3%. Overall, the average size of original austenite increased, and the precipitates changed from Ti (C, N) to Cr carbides. During the cooling process, the nucleation position of bainitic ferrite was from high to low according to the nucleation temperature, and in order of inclusions at grain boundaries, triple junctions, intragranular inclusions, bainitic ferrite/austenite phase boundaries, twin boundaries, grain boundaries, and intragranular inclusions at the bainitic ferrite/austenite phase interface. The growth rate of bainitic ferrite nucleated at the phase interface, grain boundary, and other plane defects was faster, while it was slow at the inclusions. Moreover, it was noted that the Mg-Al-Ti-O composite inclusions promote the nucleation of lath bainitic ferrite, while the Al-Ca-O inclusions do not facilitate the nucleation of bainitic ferrite.

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Section: Microstructure Of Welding Heat Affected Zonementioning

confidence: 99%

Section: Microstructure Of Welding Heat Affected Zonementioning

confidence: 99%

The Influence of the Second Phase on the Microstructure Evolution of the Welding Heat-Affected Zone of Q690 Steel with High Heat Input

Qi,

Pang,

et al. 2024

Materials

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“…Although some authors consider that the addition of nickel is expensive [10,11] and propose the adoption of cheaper elements such as silicon to increase the hardenability, they state that future work is still required to confirm the precise effect of the ferritizing alloying elements because they can cause deleterious influence on the properties due to the formation of undesirable microstructural constituents such as granular bainite [56][57][58].…”

Section: Relevant Aspectsmentioning

confidence: 99%

Evaluation of High Strength Cast Steel Welded Joints Suitable to Mooring Components

et al. 2022

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This work investigates the performance of high strength cast steel welded joints to confirm their feasibility for application in mooring components. Three welded joints, with ultimate tensile strength in the range of 700 to 900 MPa, were obtained by the shielded metal arc welding process, the most applied in repair operation. After welding, a post welding heat treatment was performed to relieve the residual stresses. The results obtained in tension, impact Charpy-V, and hardness tests, at different positions of the heat affected zone were compared with equivalent welded joints performed with rolled steels currently applied in mooring chain links. These results showed that cast steels can obtain results equivalent to the rolled steels. Furthermore, the composition of cast steels for more stringent requirements (UTS > 860 MPa) is adjusted with higher nickel contents, while rolled and forged steels show increased C, Cr, and Mo contents. As a consequence, a refined microstructure with excellent impact toughness was obtained. Thus, these steels present a high potential to be used in this application contributing to reduce manufacturing costs.

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“…Meanwhile, the typical bainite structure also plays an important role in its mechanical properties [ 11 ]. Tomita et al have pointed out that the martensite and bainite dual phase structure can significantly improve the strength and toughness of steel [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. In previous works, martensite is usually described in terms of the crystallographic features of packet, block, or lath-like structures [ 9 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Martensite/Bainite Dual Phase-Content on the Mechanical Properties of EA4T High-Speed Axle Steel

et al. 2023

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In this work, we have investigated the effect of martensite/bainite dual phase content on the mechanical properties of EA4T high-speed axle steel. For evaluation and control of the strength, ductility, and toughness of steel, the microstructure of lath martensite (LM) and granular bainite (GB) was clarified through an optical microscope (OM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). Besides, the tensile fracture morphology was studied by scanning electron microscopy (SEM). For this purpose, this study conducted a quantitative analysis of the LM and GB fractions using the Pro Imaging software-2018 of OM. The remarkable effect of the LM/GB structure on mechanical properties is discussed. The results have shown that by increasing the volume fraction of the GB structure, the LM structure is refined and its microhardness and strength are improved. Meanwhile, the micro strength of LM follows the Hall–Petch relationship with the lath martensite packet size. Subsequently, the mechanical property prediction model of EA4T steel based on the LM/GB content was established by regression analysis of all experiment dates. When the LM fraction in the steel is about 40–70%, a superior combination of strength, ductility, and toughness can be obtained in EA4T steel.

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In situ observation and electron backscattered diffraction analysis of granular bainite in simulated heat-affected zone of high-strength low-alloy steel

Cited by 9 publications

References 24 publications

The Influence of the Second Phase on the Microstructure Evolution of the Welding Heat-Affected Zone of Q690 Steel with High Heat Input

The Influence of the Second Phase on the Microstructure Evolution of the Welding Heat-Affected Zone of Q690 Steel with High Heat Input

Evaluation of High Strength Cast Steel Welded Joints Suitable to Mooring Components

Influence of Martensite/Bainite Dual Phase-Content on the Mechanical Properties of EA4T High-Speed Axle Steel

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