Dissolution Behaviour of NbC during Slab Reheating

Lee, Hongyeob; Park, Kyong-Su; Lee, Jung Hyeung; Heo, Yoon-Uk; Suh, Dong‐Woo; Bhadeshia, H. K. D. H.

doi:10.2355/isijinternational.54.1677

Cited by 24 publications

(9 citation statements)

References 16 publications

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“…However, for the 16 h samples, the niobium intensity is low compared to that of Ti peaks, indicating dissolution of NbC from the complex (Ti,Nb,V)C precipitates. Titanium in particular is known to stabilise NbC and hence retard its dissolution [116]. For the samples heated for more than 32 h, apparently no niobium containing precipitates could be observed; it is likely that the niobium is completely dissolved in austenite.…”

Section: Dissolution Kinetics In a Nb-v-ti Microalloyed High C Steelmentioning

confidence: 99%

Niobium in Microalloyed Rail Steels

Ray

Bhadeshia

2015

HSLA Steels 2015, Microalloying 2015 &Amp; Offshore Engineering Steels 2015

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Rail steels rely primarily on possessing adequate wear and rolling contact fatigue resistance. These properties, together with the toughness, can in principle be optimized by implementing thermomechanical processing assisted by controlled niobium additions. The purpose of the current work is to develop a Nb-microalloying strategy in the context of high-carbon pearlitic and cementite-free bainitic steels. The conventional methods do not leave the critical regions of a rail section in a suitably processed state. An attempt has been made for the first time, to create a pancaked austenite grain structure, with an examination of the consequences on the final Declaration This dissertation is submitted for the degree of Doctor of Philosophy at the University of Cambridge. The research reported was conducted under the supervision of

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Section: Dissolution Kinetics In a Nb-v-ti Microalloyed High C Steelmentioning

confidence: 99%

Niobium in Microalloyed Rail Steels

Ray

Bhadeshia

2015

HSLA Steels 2015, Microalloying 2015 &Amp; Offshore Engineering Steels 2015

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“…Size and distribution of MX particles re-precipitated during subsequent heating and deformation at 1173 K should be more efficient than those existing in the ascast structure. In the case of specimens heated or heated and deformed at the temperature of 1173 K, most niobium rich MX particles are expected to be inherited from the initial microstructure [51,52]. At this temperature only vanadium rich MX particles are expected to be dissolved.…”

Section: Discussionmentioning

confidence: 99%

Continuous cooling transformation diagrams of HSLA steel for seamless tubes production

Schindler

Kawulok

Seillier

et al. 2019

J min metall B Metall

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The CCT and two DCCT diagrams were constructed for the HSLA steel containing Cr, V, Nb, and N microadditions, taking into account industrial processing parameters of this material in a seamless tubes rolling mill. The typical finish hot rolling temperature of 1173 K was used for the construction of the standard CCT diagram and the effect of previous austenite deformation at this temperature was evaluated in the DCCT diagram. Another DCCT diagram was developed after heating at 1553 K, followed by plastic deformation at 1173 K. The prior austenite grain size in the hot rolled material after heating at 1173 K was approx. 10 m, the heating of the as-cast material at 1553 K resulted in the prior austenite grain size over 200 m. The effect of the previous austenite deformation after low-temperature heating on the CCT diagram was negligible. The high-temperature heating showed a great influence on the austenite decomposition processes. The Ferrite-start temperature was significantly reduced at high cooling rates and the preferred decomposition of coarse grained austenite to acicular ferrite suppressed the bainite transformation at medium cooling rates. The developed DCCT diagrams can be used for the prediction of austenite decomposition products during the cooling of the seamless tubes from the finish rolling temperature. The CCT diagram can be utilized for the quality heat treatment of tubes.

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“…Following the 1 h annealing at 650°C, annealing at 1025°C would result in an overall dissolution of precipitated TiC particles due to the increased solubility of Ti and C. However, complex evolution of average size of precipitated particles during dissolution has been observed by researchers. Lee et al [21] studied the dissolution behavior of NbC during simulated slab reheating process and found the particle coarsening phenomenon at relatively low heating rate of 0.0013°C/s. Similar to present annealing treatment, Jones and Ralph [22] investigated the dissolution of NbC in an austenitic stainless steel by annealing at 1100°C-1300°C subsequent to isothermal precipitation of NbC at 930°C.…”

Section: Parameters Expression or Valuementioning

confidence: 99%

Effect of annealing process on the abnormal grain growth behavior during carburizing of 20CrMnTi steel

Jia

Huang

Wang

et al. 2020

Mater. Res. Express

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Abnormal grain growth (AGG) as an important physical metallurgical behavior is to be avoided during carburizing due to its adverse effect on properties such as fatigue, impact toughness and the quenching distortion. In this work, two types of annealing process which produce different morphology of precipitated particles were conducted to investigate its effect on the subsequent austenite grain growth behavior during carburizing of 20CrMnTi steel. Calculation from Humphreys' model exhibited a good agreement with experimental observations, which indicates the large sized particle from high temperature annealing led to the locally insufficient pinning force for the blockage of grain boundary migration and is therefore responsible for the AGG. The isothermal precipitation kinetics for TiC particles is able to be described by the diffusional growth and LSW coarsening models with reasonable accuracy provided with the transition time from growth to coarsening stage. Design of microalloying and pre-treatment processing to suppress AGG can be assisted with the combinatory application of Humphrey's model and precipitation kinetics model.

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Dissolution Behaviour of NbC during Slab Reheating

Cited by 24 publications

References 16 publications

Niobium in Microalloyed Rail Steels

Niobium in Microalloyed Rail Steels

Continuous cooling transformation diagrams of HSLA steel for seamless tubes production

Effect of annealing process on the abnormal grain growth behavior during carburizing of 20CrMnTi steel

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