Processing of low carbon steel plate and hot strip—An overview

Panigrahi, B. K.

doi:10.1007/bf02708632

Cited by 75 publications

(47 citation statements)

References 23 publications

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“…This has been observed previously in the literature, [19][20][21] with Medina et al 20) attributing this low solute drag effect to the solution temperature of large titanium nitrides being greater than 1 250°C 22) and therefore not dissolving at the reheating temperature used in this study.…”

Section: )supporting

confidence: 87%

“…18) It is also of interest that, although the IF grade has quite a high titanium content compared to the other two grades, it displays a temperature sensitivity of softening not considerably higher than the C-Mn grade. This has been observed previously in the literature, [19][20][21] with Medina et al 20) attributing this low solute drag effect to the solution temperature of large titanium nitrides being greater than 1 250°C 22) and therefore not dissolving at the reheating temperature used in this study.…”

Section: Kinetics Of Strain Dependent Softeningsupporting

confidence: 86%

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An Analysis of the Transition between Strain Dependent and Independent Softening in Austenite

et al. 2005

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The post-deformation softening behaviour of austenite has been studied for various compositions and deformation conditions. The strain at which the transition from strain dependent to strain independent postdeformation softening behaviour occurs (e*) has been found to coincide closely with the strain to the peak stress (e p ) under certain conditions but not under others. It has been proposed that the relationship between e* and e p may be described geometrically using the initial grain size and the dynamically recrystallised grain size.KEY WORDS: static recrystallisation; metadynamic recrystallisation; dynamic recrystallisation; peak strain. Table 1. Composition (wt%) of steels used in this study.intercept grain size was then determined based on 10 random fields located 100 mm or less from the surface of each sample. The grain sizes determined for the C-Mn, HSLA and IF grades after roughing were 70 mm, 45 mm and 55 mm respectively, with very little variation over the temperature range used. ResultsInterrupted torsion tests were used to examine the effect of strain, strain rate, temperature and initial grain size upon the softening kinetics of the three grades. The relative softening, X (%), was determined from the expression: where s m is the stress at the end of first deformation, s 1 is 0.2 % offset yield stress for the first deformation and s 2 is 0.2 % offset yield stress for the second deformation. A rapid method of determining softening kinetics through the analysis of the time to 50 % softening (t 0.5 ) was adopted for this analysis (the details of which are described elsewhere 11) ). The general features of the data generated by this method may be seen in Fig. 1. The most obvious feature in this figure is the sharp change in softening behaviour once an applied strain of 0.85 is exceeded, with further deformation exerting no significant influence over the softening kinetics. The strain to the flow stress peak for these conditions falls at a strain of 0.7. In this case the transition strain (e*) was higher than the peak strain by a factor of 1.2.The softening in the strain dependent region was modelled using a power law equation with the general form. The determination of the various exponents and coefficients of the two regions is discussed below. Effect of Strain and TemperatureThe effect of temperature upon the softening kinetics of each of the three grades can be seen in Figs. 2, 3 and 4. In all cases the strain exponent for the strain dependent region was 2. As expected, increasing the temperature accelerated the kinetics of softening in all three grades. The apparent recrystallisation activation energies are given in Table 2 and it can be seen that strain independent softening is significantly less affected by temperature then strain dependent softening. Effect of Strain RateThe effect of strain rate upon the time to 50 % softening for each of the three grades is shown in Figs. 5, 6 and 7. It may be observed in all three grades that strain rate exerts a significant influence over the post-e* softeni...

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Section: )supporting

confidence: 87%

Section: Kinetics Of Strain Dependent Softeningsupporting

confidence: 86%

An Analysis of the Transition between Strain Dependent and Independent Softening in Austenite

et al. 2005

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“…The order of potential to suppress austenite grain growth is Ti>Nb>Al>V [107]. The potential to suppress is also highly related with the microalloying element concentration.…”

Section: Grain Growth Inhibition By Particle Pinningmentioning

confidence: 99%

Thermomechanical Processing of Structural Steels with Dilute Niobium Additions

Cui

Patel²,

Palmiere

2016

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

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-i - AbstractIn this thesis, the influence of various dilute Nb additions (0.005-0.02 wt%) on austenite microstructure evolution along thermomechanical processing, in terms of austenite recrystallisation and grain growth, were investigated using steels with three carbon content levels.At the homogenisation temperature of 1250°C, all dilute Nb additions were dissolved in low carbon steels whereas the Nb dissolution limits for 0.4 wt% and 0.6 wt% C steels were 0.012 wt% and 0.08 wt%, respectively. Dilute Nb additions did not show significant influence on homogenised austenite grain size. The dramatic increase in C contents was more influential, which decreased the homogenised austenite grain size.The influence of dilute Nb additions and C contents on dynamic recrystallisation behaviour was studied by rough rolling at high deformation temperature with low strain rate. The dilute Nb additions were found to increase the critical strain of dynamic recrystallisation whereas C contents showed no influence on the dynamic recrystallisation behaviour.The austenite recrystallisation behaviour after finish rolling and after the holding period between finishing passes were studied by means of interrupted plane strain compression (PSC) tests and double hit PSC tests. It was found that with low Nb supersaturation, recrystallisation happened prior to Nb precipitation. Solute Nb in austenite delayed the onset of austenite recrystallisation through solute drag effect.With high Nb supersaturation, Nb precipitation occurred before the onset of recrystallisation which completely retarded austenite recrystallisation.The austenite grain growth during the holding period between finish rolling passes was studied by the evolution of prior-austenite grain size before and after the 20s holding period at the highest finish rolling temperature (1050°C). There was no Nb precipitation found and the difference in austenite grain growth behaviour was Abstract -iiattributed to the solute drag effect from both Nb and C in solution. It was found that Nb in solution suppressed austenite grain growth. However, the effectiveness of solute Nb in suppressing austenite grain growth was affected by the C content. Acknowledgement

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“…There are numerous studies on the precipitation of carbides in microalloyed steels using both experimental and modeling approaches [1][2][3][4][5][6][7] . Most of the experimental investigations have focused on the identification of carbide types, precipitation kinetics, particle coarsening behavior and particle size distributions for different alloy additions and processing conditions, providing an understanding of the interrelationship of precipitated particles with recrystallization and grain growth phenomena [8][9][10][11][12][13] . The results have contributed to the development of steels with superior properties by adjusting compositional and thermomechanical variables.…”

Section: I In Nt Tr Ro Od Du Uc Ct Ti Io On Nmentioning

confidence: 99%

Electrochemical extraction of microalloy carbides in Nb-steel

et al. 2008

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E El le ec ct tr ro oc ch he em mi ic ca al l e ex xt tr ra ac ct ti io on n o of f m mi ic cr ro oa al ll lo oy y c ca ar rb bi id de es s i in n N Nb b--s st te ee el l ( (• •) )A.L. Rivas * , E. Vidal ** , D.K. Matlock *** and J.G. Speer *** A Ab bs st tr ra ac ct t An electrochemical extraction technique was evaluated as a characterization method of precipitates in microalloyed steels. To carry out this study, a fully precipitated Nb-modified SAE 8620, was used. The investigation was accomplished by varying the electrolyte composition and the filter pore sizes used to collect the particles. The quantification of Nb was performed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Microscopy examination was also performed on extraction replicas and on residues collected in the acetate filters. Additionally, X-ray diffraction analysis (XRD) on the collected residues containing the precipitates was accomplished. The results showed that the dissolution rate is faster in the electrolyte consisting of 10 vol% HCl in water. Additionally, transmission electron microscopy (TEM) analysis along with chemical analysis by ICP-AES, showed that (Nb,Ti)C particles were collected in acetate filters with a pore size much larger than the precipitate size.K Ke ey yw wo or rd ds s (Nb,Ti)C precipitates; Electrochemical extraction; Steel matrix dissolution; Microalloyed steel; Anodic dissolution; Filtration.E Ex xt tr ra ac cc ci ió ón n e el le ec ct tr ro oq qu uí ím mi ic ca a d de e c ca ar rb bu ur ro os s d de e m mi ic cr ro oa al le ea ac ci ió ón n e en n N Nb b--a ac ce er ro o R Re es su um me en n La técnica de extracción electroquímica fue empleada para evaluar su efectividad en la caracterización de precipitados en aceros microaleados. Para realizar el estudio, se utilizó un acero SAE 8620 modificado con niobio. La investigación se llevó a cabo variando la composición del electrolito utilizado en la disolución electroquímica de la matriz y el tamaño de poro de los filtros usados para recolectar las partículas precipitadas. La cuantificación del contenido de Nb se hizo por espectroscopia de emisión atómica de plasma (ICP-AES). Además, las muestras obtenidas por réplicas de extracción y las provenientes de los residuos recolectados en los filtros fueron analizadas mediante microscopía electrónica de transmisión. Estas últimas muestras, también fueron caracterizadas por difracción de rayos X. Los resultados mostraron que la velocidad de disolución electroquímica de las muestras es mayor en el electrolito acuoso con 10 vol. % HCl. Adicionalmente, el análisis mediante microscopía electrónica de transmisión, en combinación con los análisis químicos mediante ICP-AES, mostró que las partículas de (Nb,Ti)C son recolectadas en filtros de acetato con tamaños de poro mucho mayor que el tamaño de las partículas precipitadas. P Pa al la ab br ra as s c cl la av ve e (Nb,Ti)C precipitados; Extracción electroquímica; Disolución electroquímica de la matriz de acero; Aceros microaleados; Disolución anódica de matriz...

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Processing of low carbon steel plate and hot strip—An overview

Cited by 75 publications

References 23 publications

An Analysis of the Transition between Strain Dependent and Independent Softening in Austenite

An Analysis of the Transition between Strain Dependent and Independent Softening in Austenite

Thermomechanical Processing of Structural Steels with Dilute Niobium Additions

Electrochemical extraction of microalloy carbides in Nb-steel

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