Strain induced precipitation of complex carbonitrides in Nb–V and Ti–V microalloyed steels

Pandit, Ashwin; Murugaiyan, A.; Podder, A. Saha; Haldar, Arunansu; Bhattacharjee, D.; Chandra, Sudeshna; Ray, R.K.

doi:10.1016/j.scriptamat.2005.07.003

Cited by 77 publications

(69 citation statements)

References 9 publications

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“…The found stoichiometries of the precipitates are in good agreement with the stoichiometries calculated under equilibrium conditions. This confirms the statement of Pandit et al 26) who declared that deformation will greatly enhance the kinetics of precipitation but that the nature and the chemical composition of the precipitates is expected to remain the same as in the situation without deformation.…”

Section: Stoichiometry Of the Precipitates Measured Bysupporting

confidence: 89%

Austenite Recrystallization–Precipitation Interaction in Niobium Microalloyed Steels

et al. 2009

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A good combination of strength and toughness in HSLA steels can be achieved by the addition of microalloying elements such as Nb. Nb can retard the static recrystallization of austenite at lower temperatures by solute drag or by precipitation pinning. In this study, the recrystallization behavior of four Nb-microalloyed model alloys which were designed to show either extensive or almost no precipitation, was compared by multi-hit torsion tests and double hit compression tests. A good consistency between the different types of tests was found and the results were verified by optical micrographs. Further, by construction of softeningtime-temperature diagrams the recrystallization behavior was linked to the precipitation state of the material which was investigated by thermodynamical equilibrium calculations and by experimental observations from TEM-EDX, Inductively Coupled Plasma Mass Spectroscopy and X-ray Diffraction. Quantitative agreement between the experimental measurements and the calculations for precipitated mass fraction and precipitate composition as a function of temperature and steel composition is demonstrated.KEY WORDS: recrystallization; microalloyed steels; precipitation; solute drag. 911© 2009 ISIJ tions with experimental data from Craven et al. 13)The objective of the present paper is to separate both retarding mechanisms, i.e. solute drag and precipitation pinning, by investigating model alloys designed to show either extensive or almost no precipitation. Moreover, the recrystallization kinetics of four Nb-microalloyed steels during hot deformation is linked to the morphology and composition of the precipitates and the amount of Nb-solutes found in these materials. The recrystallization kinetics were investigated combining different hot deformation testing techniques while information on the precipitation state of the material was obtained from thermodynamic equilibrium calculations and from a combination of experimental observation techniques. With this work, a contribution to the understanding of the fundamental mechanisms responsible for the retardation of austenite recrystallization in Nb-microalloyed steels is achieved. Experimental ProcedureFour model alloys were designed and casted as 100 kg ingots in a Pfeiffer vacuum furnace operated under argon gas atmosphere. The chemical composition of these alloys can be found in Table 1. The C-Mn-reference alloy, without additional Nb, represents a reference steel. The second alloy, a lowC-Mn-Nb alloy containing only a few ppm C, allowed to study the effect of Nb in solid solution. The third alloy (C-Mn-Nb) was designed to study the effect of NbC-precipitates on the recrystallization kinetics. To have the highest fraction of NbC precipitates possible, a stoichiometric Nb/C-ratio of 8/1 was chosen. Finally, the fourth alloy (C-Mn-Nb-N) was designed to study the influence of N on the recrystallization and precipitation behavior. The cast blocks were thermomechanically processed under conditions comparable to those during industrial steel plate rolli...

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Section: Stoichiometry Of the Precipitates Measured Bysupporting

confidence: 89%

Austenite Recrystallization–Precipitation Interaction in Niobium Microalloyed Steels

et al. 2009

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“…The found stoichiometries of the precipitates are in good agreement with those calculated under equilibrium conditions [9]. This confirms the statement of Pandit et al [11] who declared that deformation will greatly enhance the kinetics of precipitation but that the nature and the chemical composition of the precipitates is expected to remain the same as in the case without deformation. After the identification of the precipitates, a precipitation-time-temperature diagram can be constructed, see Figure 3.…”

Section: Methodssupporting

confidence: 89%

Control of the Austenite Recrystallization in Niobium Microalloyed Steels

Vervynckt

Verbeken

Thibaux

et al. 2010

MSF

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Abstract. The use of heavy gauge steel sheets for structural applications very often requires a combination of high yield strength and adequate toughness. The most cost effective way to realize a high yield strength and a high ductility in a low alloyed steel is grain refinement. In industrial practice, this refinement is realized by controlled processing. This process consists of controlling the slab reheating temperature, applying a large amount of hot deformation below the nonrecrystallization temperature (T nr ) and accelerated cooling. A better knowledge of T nr could optimize the process and the best mechanical properties could be reached against the lowest cost. T nr can be raised by the addition of microalloying elements such as Nb. Nb can retard the static recrystallization of austenite at low temperatures either by solute drag or by precipitation pinning. In this study, the recrystallization behavior of five Nb-microalloyed model alloys with various Nb contents, was evaluated by double hit compression tests. Further, the precipitation state of the materials was investigated experimentally by Inductively Couples Mass Spectroscopy and X-ray Diffraction. The construction of recrystallization-time-temperature diagrams and precipitation-timetemperature diagrams showed that both mechanisms, i.e. recrystallization and precipitation, strongly influence each other.

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“…In the MoNbV-steel, the particles were mainly of two types: NbV-containing with/without Mo and Mo-containing without Nb or V. In the CrNbV-steel, the particles were also of two types: NbV-containing and Nb-containing ( Figure 6). Detailed characterisation of the particle compositions was outside of this paper scope; however, on the basis of previously published data we believe that NbV-containing particles were MX type NbV(CN) [44][45][46], MoNbV-containing ones were MoNbVC [13,47], and Mo-containing ones could be complex FeMoC [48]. The average particle number density and area fraction were lower in the MoNbV-steel, compared to the CrNbV-steel, for both processing conditions (Table 1).…”

Section: Particle Precipitationmentioning

confidence: 90%

Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels

Kostryzhev

Singh

Chen

et al. 2018

Metals

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Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the route to optimise steel composition and keep the properties high. However, this requires deep understanding of mutual effects of elements on each other's performance with respect to the development of microstructure and mechanical properties. This knowledge is insufficient at the moment. In the present work we investigate the microstructure and mechanical properties of bainitic steels microalloyed with Cr, Mo, Nb and V. Comparison of 0.2 wt. % Mo and Cr additions has shown a more pronounced effect of Mo on precipitation than on phase balance. Superior strength of the MoNbV-steel originated from the strong solid solution strengthening effect. Superior ductility of the CrNbV-steel corresponded to the more pronounced precipitation in this steel. Nature of these mechanisms is discussed.

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Strain induced precipitation of complex carbonitrides in Nb–V and Ti–V microalloyed steels

Cited by 77 publications

References 9 publications

Austenite Recrystallization–Precipitation Interaction in Niobium Microalloyed Steels

Austenite Recrystallization–Precipitation Interaction in Niobium Microalloyed Steels

Control of the Austenite Recrystallization in Niobium Microalloyed Steels

Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels

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