Effect of Nb addition on the microstructure and mechanical properties of an 1800MPa ultrahigh strength steel

Wu, Huibin; Biao, Ju; Tang, Di; Rirong, Hu; Guo, Aimin; Kang, Qiang; Wang, Di

doi:10.1016/j.msea.2014.11.005

Cited by 58 publications

(29 citation statements)

References 30 publications

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“…Two possible reasons could account for this phenomenon. Firstly, Wu and co-workers claimed that Nb atoms in solid solution tended to segregate at grain boundaries and hence, retarded the prior austenite grain growth due to the solute drag effect [34]. In the Steel ESR, there were more Nb atoms in solid solution in spite of the lack of primary NbC carbides, theoretically producing a stronger solute drag effect.…”

Section: Discussionmentioning

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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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: 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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“…Steel has played and will continue to play a major role in the development of modern societies [1][2][3]. Materials scientists continue to devote themselves to the development of new steels in order to meet the ever-increasing demands for better performing steels [4][5][6][7]. The design of new steels with desired combinations of sometimes contradictory properties is a challenging task as many variables and their complex interactions should be taken into account.…”

Section: -Introductionmentioning

confidence: 99%

Computational Design of a Novel Medium-Carbon, Low-Alloy Steel Microalloyed with Niobium

Javaheri

Nyyssönen

Grande

et al. 2018

J. of Materi Eng and Perform

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The design of a new steel with specific properties is always challenging owing to the complex interactions of many variables. In this work, this challenge is dealt with by combining metallurgical principles with computational thermodynamics and kinetics to design a novel steel composition suitable for thermomechanical processing and induction heat treatment to achieve a hardness level in excess of 600 HV with the potential for good fracture toughness. CALPHAD-based packages for the thermodynamics and kinetics of phase transformations and diffusion, namely Thermo-Calc ® and JMatPro ® , have been combined with an interdendritic segregation tool (IDS) to optimize the contents of chromium, molybdenum and niobium in a proposed medium-carbon low-manganese steel composition. Important factors taken into account in the modelling and optimization were hardenability and as-quenched hardness, grain refinement, and alloying cost. For further investigations and verification, the designed composition, i.e. in wt.% 0.40C, 0.20Si, 0.25Mn, 0.90Cr, 0.50Mo, was cast with two nominal levels of Nb: 0 and 0.012 wt.%. The results showed that an addition of Nb decreases the austenite grain size during casting and after slab reheating prior to hot rolling. Validation experiments showed that the predicted properties i.e. hardness, hardenability and level of segregation for the designed composition were realistic. It is also demonstrated that the applied procedure could be useful in reducing the number of experiments required for developing compositions for other new steels.

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“…Kuzucu et al also found that the addition of Nb prevented the formation of M 23 C 6 carbides, while the formation of MC carbides is promoted. Wu et al reported that the martensite microstructure was refined and the formation of harmful iron carbides was retarded with Nb addition. However, little work has been devoted to the effect of Nb on Cr–Mo–V steel for brake discs.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nb and Tempering Time on Carbide Precipitation Behavior and Mechanical Properties of Cr–Mo–V Steel for Brake Discs

Wang

Cheng

et al. 2018

steel research int.

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To improve the performance of the steel for brake discs, like mechanical properties and thermal fatigue resistance, Nb is added to the steel. In this paper, the effects of Nb and tempering time on the microstructure and mechanical properties of the steel have been studied. The investigation of precipitation behaviors is based on Thermo‐Calc software and transmission electron microscopy. The results show there is a negative linear relationship between the yield strength and the logarithm of time, and tempering time should not exceed 2 h. V‐rich M8C7 and NbC occur during austenitizing, while (Mo,V)C, M23C6, and M7C3 precipitate during tempering. (Mo,V)C has a strong strengthening effect at the early stage of tempering, but it grows faster than M8C7. With 0.025% Nb addition, the yield strength and impact energy increase simultaneously due to the refinement of martensite; the addition of 0.045% Nb promotes the tempering stability due to the suppression of precipitation and coarsening of Cr carbides and the precipitation strengthening of M8C7 and NbC, therefore, the addition of 0.025–0.045% Nb is conducive to improving the performance of the steel. Moreover, the suppression of Cr carbides with 0.045% Nb addition makes up for the damage of large NbC to toughness.

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Effect of Nb addition on the microstructure and mechanical properties of an 1800MPa ultrahigh strength steel

Cited by 58 publications

References 30 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

Computational Design of a Novel Medium-Carbon, Low-Alloy Steel Microalloyed with Niobium

Effects of Nb and Tempering Time on Carbide Precipitation Behavior and Mechanical Properties of Cr–Mo–V Steel for Brake Discs

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