Effect of NbC and VC carbides on microstructure and strength of high-strength low-alloyed steels for oil country tubular goods

Zeng, Tianyi; Zhang, Shuzhan; Shi, Xianbo; Wang, Wei; Yan, Wei; Yang, Ke

doi:10.1016/j.msea.2021.141845

Cited by 31 publications

(7 citation statements)

References 26 publications

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“…As Taylor suggested [36], the Taylor factor is a geometric factor that evaluates the trend of a crystal to slip concerning the orientation of the crystal relative to the sample According to Figure 10, when the studied steels were tempered at 690 • C (i.e., 963 K), there were several precipitation phases in the BCC matrix, which were mainly cementite, M 23 C 6 , MC, and so forth. However, based on the EDS results and our previous work [22], the Cr-rich carbides should dominate. It was reported that strong carbide forming elements such as Nb could effectively refine the size of Cr-rich carbides by preferentially combining with C in solid solution to form carbides [35].…”

Section: Discussionmentioning

confidence: 52%

“…The dislocation densities in Steel CC and ESR were evaluated by the convolutional multiple whole profile (CMWP) fitting procedure. In CMWP, the peak profile functions were firstly assumed to be the convolution of the grain size, strain, and instrumental broadening (evaluated using annealed Si powders), and then the measured XRD profile was fitted with the calculated peak profile functions based on a non-linear least-squares method [20][21][22]. The volume fraction of retained austenite was calculated according to the ASTM E975-03 standard [23].…”

Section: Methodsmentioning

confidence: 99%

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Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

et al. 2021

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Sulfide stress corrosion cracking (SSCC) has been of particular concern in high strength low alloyed (HSLA) steels used in the oil industry, and the non-metallic inclusions are usually considered as a detrimental factor to the SSCC resistance. In the present work, continuous casting (CC) and electroslag remelting (ESR) were adopted to fabricate a 125 ksi grade steel in order to evaluate the effect of microstructure with and without primary NbC carbides (inclusions) on the SSCC resistance in the steel. It was found that ESR could remove the primary NbC carbides, and hence, slightly increase the strength without deteriorating the SSCC resistance. The elimination of primary NbC carbides caused two opposite effects on the SSCC resistance in the studied steel. On the one hand, the elimination of primary NbC carbides increased the dislocation density and the proportion of high angle boundaries (HABs), which was not good to the SSCC resistance. On the other hand, the elimination of primary NbC carbides also induced more uniform nanosized secondary NbC carbides formed during tempering, providing many irreversible hydrogen traps. These two opposite effects on SSCC resistance due to the elimination of primary NbC carbides were assumed to be offset, and thus, the SSCC resistance was not greatly improved using ESR.

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Section: Discussionmentioning

confidence: 52%

Section: Methodsmentioning

confidence: 99%

Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

et al. 2021

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“…The diffraction spots show that there was an orientation relationship between M 23 C 6 and VC represented in

. Previous studies have shown that there is a certain probability that the MC phase can become the core of the heterogeneous nucleation of M 23 C 6 [ 29 , 30 , 31 ]. The (111) crystal plane of the face-centered cubic VC has atomic accumulation to become the M 23 C 6′ s nucleation point.…”

Section: Resultsmentioning

confidence: 99%

The Effect of the Pre-Existing VC on the Evolution of Precipitate and Mechanical Properties in the H13 Steel

et al. 2022

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To further improve the mechanical properties of H13 steel at room and high temperatures, its precipitates were regulated based on the Thermo-Calc results. Scanning electron microscope (SEM), electron backscattering diffraction (EBSD), transmission electron microscope (TEM), and X-ray diffraction (XRD) Rietveld refinement were used to study the effect of the intercritical annealing on the microstructure and mechanical properties of H13 steel. The results show that the intercritical annealing at 850~95 °C increased the VC volume fraction from 2.23 to 3.03~3.48%. Increasing the VC volume fraction could inhibit the M7C3 precipitation from 10.01 to 6.63~5.72% during tempering. A large amount of VC also promoted the M23C6 precipitation during tempering at higher dislocation densities. The intercortical annealing simultaneously increased the elongation of H13 steel. An excellent combination (room temperature: ultimate tensile strength (UTS) of 898 MPa and total elongation (TEL) of 19.35%, 650 °C: UTS of 439 MPa, and TEL of 27.80%) could be obtained when intercritical annealing is performed at 900 °C. Meanwhile, after aging at 650 °C for 128 h, the room temperature UTS and TEL decreased by only 31 MPa and 0.52%, respectively.

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“…4.1. Effect of normalizing temperature on the microstructure evolution Zeng et al [29] emphasized that NbC and VC carbides in high-strength low-alloy oil pipes and tube steels inhibited the growth of prior austenite grains during austenitization. According to Li et al [30], large-sized M 23 C 6 carbides were eliminated by austenitization at 1050 °C in martensitic heat-resistant steels.…”

Section: Discussionmentioning

confidence: 99%

Effects of normalizing temperature on microstructure and high-temperature properties of 2.25Cr-1Mo-0.25V bainitic steel

Zhang

Luo

et al. 2023

Mater. Res. Express

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In 2.2Cr-1Mo-0.25V bainitic steels, the effect of the initial microstructure on carbide precipitation has not yet been elucidated. Therefore, in this work, the effect of normalizing temperature on the microstructure evolution and corresponding high-temperature strength change of bainitic steels was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) using extra-thick hydrogenation reactor steel as the assessed material, and the precipitation strengthening mechanism was discussed. When the normalizing temperature increased from 900°C to 990°C, the high-temperature yield strength increased from 451 to 475 MPa and the average absorbed Charpy impact energy at -30°C decreased from 93 to 41 J. Therefore, the optimal normalizing temperature was 960°C. The volume fraction of MC carbides with almost no change in average diameter increased from 0.21% to 0.44%, and the dispersed strengthening of carbide was significantly enhanced. The increase in normalizing temperature increased the solid solution of alloying elements within the bainite matrix, which increased the precipitation of MC carbides during the tempering process. In addition, the lamellar M-A constituents in the initial microstructure decomposed to form MC carbides.

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Effect of NbC and VC carbides on microstructure and strength of high-strength low-alloyed steels for oil country tubular goods

Cited by 31 publications

References 26 publications

Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

Effects of the Primary NbC Elimination on the SSCC Resistance of a HSLA Steel for Oil Country Tubular Goods

The Effect of the Pre-Existing VC on the Evolution of Precipitate and Mechanical Properties in the H13 Steel

Effects of normalizing temperature on microstructure and high-temperature properties of 2.25Cr-1Mo-0.25V bainitic steel

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