On the Behavior of Precipitates in the Nb&amp;ndash;Mo Heat-Treated High Strength Steel having 80 kg/mm&lt;SUP&gt;2&lt;/SUP&gt; Tensile Strength

Kanazawa, Shogo; Nakashima, Akira; Okamoto, K.; Tanabe, Koji; Nakazawa, Susumu

doi:10.2320/matertrans1960.8.113

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…11b) are most probably complex Nb carbonitrides where Mo is introduced in the lattice. In fact, several references indicate that Ti/Nb carbonitrides and carbides precipitated in the austenite are significantly complex in nature and can also have a certain amount of Mo [39,[43][44][45][46] even though reported mean sizes are usually coarser than those found in this work.…”

Section: Resultsmentioning

confidence: 61%

“…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: 98%

“…The addition of Mo to low carbon Nb microalloyed steels causes an additional solute drag effect that helps to increase the value of T nr temperature, although this effect is weaker for increasing Nb additions [37,38]. On the other hand, Mo in solution is known to delay the precipitation of NbCN in Nb-Mo microalloyed steels [36,39]. Consequently, the precipitation of fine Nb-Mo precipitates in the ferrite that are beneficial for strengthening is easier [16] and accordingly the importance of final cooling and coiling temperatures to enhance precipitation strengthening has been suggested [8].…”

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: 61%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…However, as with Fe 3 C, MnS is unstable in acid. Both Fe 3 C and MnS cannot be extracted by acid solutions, as reported by Kanazawa et al [28] and Bandi.…”

Section: Tem Analysis Of Nanoprecipitates Extracted By Matrix Dissolumentioning

confidence: 70%

Matrix Dissolution Techniques Applied to Extract and Quantify Precipitates from a Microalloyed Steel

Lü

Wiskel

Omotoso

et al. 2010

Metall Mater Trans A

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Microalloyed steels possess good strength and toughness, as well as excellent weldability; these attributes are necessary for oil and gas pipelines in northern climates. These properties are attributed in part to the presence of nanosized carbide and carbonitride precipitates. To understand the strengthening mechanisms and to optimize the strengthening effects, it is necessary to quantify the size distribution, volume fraction, and chemical speciation of these precipitates. However, characterization techniques suitable for quantifying fine precipitates are limited because of their fine sizes, wide particle size distributions, and low volume fractions. In this article, two matrix dissolution techniques have been developed to extract precipitates from a Grade100 (yield strength of 690 MPa) microalloyed steel. Relatively large volumes of material can be analyzed, and statistically significant quantities of precipitates of different sizes are collected. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) are combined to analyze the chemical speciation of these precipitates. Rietveld refinement of XRD patterns is used to quantify fully the relative amounts of the precipitates. The size distribution of the nanosized precipitates is quantified using dark-field imaging in the TEM.

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High-strength structural steels with a structure of low-carbon bainite subjected to thermomechanical treatment

Lauprecht¹,

Imgrund²,

Coldren³

1975

Met Sci Heat Treat

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On the Behavior of Precipitates in the Nb–Mo Heat-Treated High Strength Steel having 80 kg/mm<SUP>2</SUP> Tensile Strength

Cited by 8 publications

References 2 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

Matrix Dissolution Techniques Applied to Extract and Quantify Precipitates from a Microalloyed Steel

High-strength structural steels with a structure of low-carbon bainite subjected to thermomechanical treatment

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