Kinetics and Crystallography of Intragranular Pearlite Transformation Nucleated at (MnS+VC) Complex Precipitates in Hypereutectoid Fe-Mn-C Alloys.

Guo, Zhenghong; Kimura, N.; Tagashira, S.; Furuhara, Tadashi; Maki, Tadashi

doi:10.2355/isijinternational.42.1033

Cited by 26 publications

(20 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They proposed that the non-equilibrium C-depleted zone around VC precipitated at the austenite grain boundary promotes the formation of such a ferrite in spite that the nominal composition should result in proeutectoid cementite precipitation. The present authors proposed a similar mechanism for the formation of intragranular pearlite on MnSϩVC complex precipitates in an Fe-Mn-C-V alloy, 8) of which composition is about the same as that of Han et al The complex transformation behavior with aging time at 1 173 K seen in Fig. 10 implies that non-equilibrium precipitation of V(C,N) affects strongly the kinetics of intragranular ferrite transformation as in the case of intragranular pearlite formation on the complex precipitate.…”

Section: Effect Of Inhomogeneous Distribution Of Alloyingmentioning

confidence: 88%

“…Recently, some of the present authors reported an acceleration of pearlite transformation by the formation of MnSϩVC complex precipitates in Fe-12Mn-0.8C alloys with V addition. 8) However, there was no systematic study that examined the potency of inclusions as the nucleation site of ferrite in terms of the amount of MnS and V(C,N) during isothermal ferrite transformation.…”

Section: Introductionmentioning

confidence: 99%

“…The expansion coefficient of VC or VN is smaller than MnS so that a larger stress effect can be expected for VC and V(C,N) as discussed previously. 8,17) However, such elastic stresses are so large that plastic accommodation should take place in austenite by forming dislocations around the inclusion or precipitate. 17,18) Thus, in the present study, slight hot deformation of austenite was performed before ferrite transformation in order to study the effect of dislocations on the intragranular ferrite transformation in the specimen containing complex precipitate.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Nucleation of Proeutectoid Ferrite on Complex Precipitates in Austenite

et al. 2003

Self Cite

View full text Add to dashboard Cite

Effect of various intragranular inclusions or precipitates (MnS, VC and V(C,N)) on the microstructure and kinetics of intragranular ferrite transformation at the temperatures between 973 and 823 K was studied using various Fe-2Mn-(0.13, 0.2)C(mass%) alloys with the small addition of sulfur, vanadium, and nitrogen. In Fe-2Mn-0.13C-50ppmS and Fe-2Mn-0.2C-470ppmS alloys, MnS particles, mostly incoherent in austenite, do not act as effective nucleation sites of ferrite. V addition slightly improves the potency of MnS as ferrite nucleation site by forming MnSϩVC complex precipitates. The addition of both V and N largely enhances the intragranular nucleation of ferrite idiomorph on the MnSϩV(C,N) complex precipitate. It is considered that two factors, i.e., (1) the advantage in the balance of interphase boundary energy and (2) the increase in the fraction of V(C,N) precipitate by the addition of nitrogen, are mainly responsible for the promotion of intragranular ferrite formation on the MnSϩV(C,N) complex precipitate.KEY WORDS: phase transformation; precipitation; steel; austenite; ferrite; carbide; nitride; sulfide; inclusion; crystallography; interphase boundary. contain similar dispersion of MnS as that of Steel C. In Steel D, VC precipitates in austenite with the addition of 0.3 mass% V. V(C,N) precipitation occurs in Steel E due to the addition of both V and N. The solution temperatures of inclusion/precipitate phases in austenite were calculated by using the solubility product equation proposed by Turkdogan 9) for MnS and Thermo-Calc for VC and V(C,N). Figure 1 shows the heat treatments employed in the present study. Austenitizing was made at 1 473 K for 0.6 ks after homogenizing at 1 473 K for 43.2 ks of hot-rolled plates. The average grain sizes of austenite after this treatment were 520 mm for Steel A, 450 mm for Steel B, and nearly equal to 150 mm for all of Steels C-E. After austenitizing at 1 473 K, the precipitation treatments of VC and V(C,N) at 1 173 K for various periods were performed for Steels D and E, followed by isothermal holding in the temperature range between 973 and 823 K to promote proeutectoid ferrite transformation.Microstructures of the transformed specimens were observed by means of optical, scanning and transmission electron microscopy (SEM and TEM). Volume fractions of ferrite were determined by point counting in optical micrographs. Electron probe microanalyzer (EPMA) and TEM-EDS (energy dispersive X-ray spectroscopy) analyses were made for identifying precipitate phases which act as ferrite nucleation sites. For optical and SEM observations, specimens were etched with 5 % nital. TEM thin foil specimens, 3 mm in diameter, were prepared by mechanical thinning followed by Argon ion thinning. TEM observation was performed by using Joel JEM-200CX and Philips CM200, CM200FEG operated at 200 kV. Figure 2(a) shows the optical microstructure of the specimen water-quenched after austenitizing in Steel C containing 470 ppm of S. Because the specimens were hot-rolled, MnS particles are aligned ...

show abstract

Section: Effect Of Inhomogeneous Distribution Of Alloyingmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Nucleation of Proeutectoid Ferrite on Complex Precipitates in Austenite

et al. 2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…Mapping combining SEI and EBSD has been successfully used for studying nucleation and growth of pearlite during pearlite transformation (Mangan & Shiflet, 1999;Guo et al, 2002;Kral & Spanos, 2003). It is accepted that surface contamination of the specimen after EBSD mapping can be removed after a very slight polish and the SEI images of the mapped region can be obtained through etching of the sample.…”

Section: Bsei Compared To Sei For Combining With Ebsdmentioning

confidence: 99%

“…The morphology of pearlitic structure can be determined by secondary electron imaging (SEI) in scanning electron microscope (SEM), whereas the crystallographic orientation of ferrite matrix (pearlite nodular) is generally determined by electron backscatter diffraction (EBSD). Combining SEI image and EBSD micrograph, both the morphology and crystallographic orientation of the pearlite can be revealed (Mangan & Shiflet, 1999;Guo et al, 2002;Kral & Spanos, 2003;Walentek et al, 2006). In the previous method, EBSD mapping was conducted firstly followed by etching of the specimen for acquisition of high-contrast SEI images.…”

Section: Introductionmentioning

confidence: 99%

Back‐scattered electron imaging combined with EBSD technique for characterization of pearlitic steels

Guo

Liu

2012

Journal of Microscopy

View full text Add to dashboard Cite

SummaryMicrostructure of pearlitic steels subjected different heat treatments were characterized combining the usage of backscattered electron imaging and electron backscatter diffraction in a scanning electron microscope. The results indicated that the method used in current study enabled the acquisition of pearlite nodule, colony and interlamellar spacing of pearlite structure only through sample preparation of one time. Both the morphology of pearlite lamellae and the crystallographic orientation of ferrite matrix can be released in backscattered electron imaging image and electron backscatter diffraction micrograph acquired at the same region. The definitions of pearlite colony and the low-angle boundaries existed in ferrite matrix were also discussed based on this method.

show abstract

Enhancement of Pearlite Nucleation by Deformation of Austenite Matrix in an Fe–12Mn–0.8C Alloy

Kimura

Maki

2012

steel research int.

View full text Add to dashboard Cite

The effect of plastic deformation of austenite on the nucleation of pearlite was investigated using an Fe–12Mn–0.8C (mass%) alloy. Slight warm deformation of austenite prior to pearlite transformation effectively accelerates the intragranular nucleation of pearlite although intragranular pearlite is hardly formed without deformation. Formation of pearlite at annealing twin boundaries is promoted in the warm‐rolled specimens. Additionally MnS particles are activated as intragranular nucleation sites of pearlite. Cold rolling of austenite introduces many deformation twins in the alloy used. Subsequent isothermal transformation heat treatments result in nucleation of pearlite at intersections of the deformation twins. It is concluded that incoherent portions introduced by deformation onto the annealing or deformation twin boundaries are effective nucleation sites in the pearlite transformation.

show abstract

Kinetics and Crystallography of Intragranular Pearlite Transformation Nucleated at (MnS+VC) Complex Precipitates in Hypereutectoid Fe-Mn-C Alloys.

Cited by 26 publications

References 23 publications

Nucleation of Proeutectoid Ferrite on Complex Precipitates in Austenite

Nucleation of Proeutectoid Ferrite on Complex Precipitates in Austenite

Back‐scattered electron imaging combined with EBSD technique for characterization of pearlitic steels

Enhancement of Pearlite Nucleation by Deformation of Austenite Matrix in an Fe–12Mn–0.8C Alloy

Contact Info

Product

Resources

About