Interaction Between Elements Nb and Mo During Precipitation in Microalloyed Austenite

Yuan, Shuai; Guoli, Liang; Zhang, Xiaojuan

doi:10.1016/s1006-706x(10)60143-4

Cited by 28 publications

(16 citation statements)

References 11 publications

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“…Morich carbides can be found in pipeline steels, but these particles are often assumed to precipitate in the ferritic domain [40]. For example, Yuan et al [42] did not find strain induced precipitation of Mo carbonitrides at 850 • C in a low carbon steel with a single addition of 0.33% Mo. The precipitation of pure Mo carbides at temperatures near 1000 • C appears as improbable for typical low-carbon, low-alloy compositions of pipeline steels with single additions of Mo [36].…”

Section: Resultsmentioning

confidence: 99%

“…Mo is interchangeable in the precipitate lattice, as happens with the combinations of V, Nb and Ti that form complex face-centered cubic (f.c.c.) carbonitrides [11,13,32,39,42,77,78]. The fine particles detected in austenite at lower temperatures (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In fact, it is usually assumed that fine Mo carbides or carbonitrides do not form in austenite and only precipitate during transformation or already in the ferrite phase [36,40,41]. The absence of Mo precipitates in austenite might be true for pure Mo carbonitrides formed with single Mo additions [42], but it has been observed that Ti and Nb carbonitrides or carbides precipitated in the austenite are significantly complex in nature and can also include a certain amount of Mo [39,[43][44][45][46]. This work makes an effort to characterize the complex Mo-containing particles formed in austenite.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of microstructure and precipitation state during thermomechanical processing of a X80 microalloyed steel

Gómez¹,

Vallés

Medina³

2011

Materials Science and Engineering: A

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a b s t r a c tA series of anisothermal hot torsion tests were carried out to simulate hot rolling on a high-strength low-carbon CMnNbMoTi microalloyed steel corresponding to an industrial X80 grade for pipeline construction. Mean Flow Stress was graphically represented against the inverse of temperature to characterize the evolution of austenite microstructure during rolling, which was also studied by optical microscopy and SEM on samples quenched from several temperatures. On the other hand, particles precipitated at different temperatures during rolling were analyzed by means of TEM using the carbon extraction replica technique and their size distribution and mean size were determined, as well as their morphology, nature and chemical composition. The effect of rolling temperature and austenite strengthening obtained at the end of thermomechanical processing on final microstructure and precipitation state was studied. Austenite strengthening was characterized by means of the parameter known as accumulated stress ( ). It was found that ferrite grains are finer and more equiaxed when the austenite is more severely deformed during finishing (higher values of ) but lower values of generate a higher density of acicular structures after cooling, which should improve the balance of mechanical properties. The increase in strength associated to acicular ferrite compared to polygonal ferrite is revealed by the higher values of Vickers microhardness measured on samples corresponding to low . On the other hand, (Ti, Nb)-rich carbonitrides can be found from reheating and their size keeps a constant value near 20-30 nm during thermomechanical processing. A second population of much finer (Nb, Mo)-rich carbonitrides whose size is close to 5 nm forms from lower temperatures, near 1000 • C. The accomplishment of two different levels of at the end of hot rolling schedule does not seem to introduce major differences in precipitation state before final cooling.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evolution of microstructure and precipitation state during thermomechanical processing of a X80 microalloyed steel

Gómez¹,

Vallés

Medina³

2011

Materials Science and Engineering: A

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“…The improvement in mechanical properties from TMCP is due to the refinement of the austenite microstructure, maximising the austenite boundary area and deformation band density, subsequently increasing the number of nucleation sites prior to the development of the transformation microstructure. The enhanced mechanical properties of lowcarbon microalloyed steels thereby arises from a combination of the refined ferrite grain size and the dispersion hardening through the precipitation in ferrite [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Dissolution and precipitation behaviour in steels microalloyed with niobium during thermomechanical processing

2015

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“…6,7) Nb usually facilitates grain refinement through the precipitation of carbides or carbonitrides in austenite thereby inhibiting the static recrystallisation of austenite, resulting in a fine final microstructure. 8) Ti has frequently been added to HSLA steels to enhance the control of austenite and transformed ferrite grain sizes during deformation and subsequent heat treatment. 9) Precipitation of Nb and Ti in Nb-Ti microalloyed steels is particularly sensitive to the coiling temperature.…”

Section: Effects Of Coiling Temperature On Microstructure and Precipimentioning

confidence: 99%

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

Tang

2018

ISIJ International

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This paper presents our latest studies on the effects of coiling temperature on the microstructure, precipitation behavior, and mechanical properties of an Nb-Ti microalloyed steel produced by endless strip processing (ESP) and coiled at different temperatures. The amounts of soluble elements were measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The microstructure and precipitates were analyzed using SEM, EBSD, TEM, and electrolytic dissolution and filtration tests. The results revealed that large amounts of microalloying elements were still in solution before coiling. As the coiling temperature decreased from 600°C to 560°C, the content of acicular ferrites (AF) increased and the average ferritic grain size was refined from 2.01 μm to 1.29 μm, the yield strength and tensile strength of the tested steel increased by 22 MPa and 20 MPa, respectively, under the effect of microstructural strengthening. As the coiling temperature increased from 600°C to 640°C, the mass fraction of precipitates increased from 0.083% to 0.110% and the percentage of fine precipitates (smaller than 18 nm) increased from 12.2% to 14.7%; the intense precipitation strengthening effect increased the yield strength and tensile strength by 35 MPa and 42 MPa, respectively. Therefore, as the coiling temperature decreased from 640°C to 560°C, the strength of the tested steel decreased first and then increased while the elongation decreased steadily from 18.9% to 14.1% due to the increasing content of AF.

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Interaction Between Elements Nb and Mo During Precipitation in Microalloyed Austenite

Cited by 28 publications

References 11 publications

Evolution of microstructure and precipitation state during thermomechanical processing of a X80 microalloyed steel

Evolution of microstructure and precipitation state during thermomechanical processing of a X80 microalloyed steel

Dissolution and precipitation behaviour in steels microalloyed with niobium during thermomechanical processing

Effects of Coiling Temperature on Microstructure and Precipitation Behavior in Nb–Ti Microalloyed Steels

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