Process Factors for Cold-rolled Dual-phase Sheet Steels

Furukawa, Takashi; Morikawa, Hirofumi; Endo, Masao; Takechi, Hiroshi; Koyama, Kazuo; Akisue, Osamu; Yamada, Toru

doi:10.2355/isijinternational1966.21.812

Cited by 26 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The open symbols represent conventional CG dual phase steels and the closed ones are available data on UFG dual phase steels. 12,13,18,26,27,[32][33][34][35] The results for UFG dual phase structures in this study are comparable to those reported in the literature. These data are at or above the upper limit for the balance in CG dual phase steels depicted by the solid line.…”

Section: Discussionsupporting

confidence: 86%

Formation of Ultrafine Grained Dual Phase Steels through Rapid Heating

2011

View full text Add to dashboard Cite

In this study, ultrafine grained dual phase structures have been developed in a plain low carbon steel, 0.17C and 0.74Mn (wt pct). The approach is based on rapid heating of a very fine ferrite-carbide aggregate into the intercritical annealing region followed by water quenching. This rapid heat treatment results in an ultrafine grained dual phase steel with improved properties. The effect of thermomechanical processing parameters such as heating rate and intercritical annealing time on the microstructure and mechanical properties have been examined. The key factors contributing to the grain refinement are uniform distribution of nanosize cementite particles acting as potential sites for austenite nucleation as well as the limited time available for coarsening of the microstructure. The mechanical properties of the present ultrafine grained dual phase steel show an excellent combination of strength and uniform elongation because of considerable work hardening.

show abstract

Section: Discussionsupporting

confidence: 86%

Formation of Ultrafine Grained Dual Phase Steels through Rapid Heating

2011

View full text Add to dashboard Cite

show abstract

“…60) Additionally, the increasing fraction of retained austenite stemming from the higher carbon content in austenite was shown to be important for the improved ductility. 61) In the present case, slower cooling leads to the break-up of large martensite islands and martensite bands, hence, yielding a fine martensite distribution that cannot be achieved by lowering the intercritical annealing temperature or holding time. Generally, a fine martensite dispersion is desirable for good formability properties.…”

Section: Implications For Mechanical Propertiesmentioning

confidence: 69%

Microstructure Control during Fabrication of Ultrafine Grained Dual-phase Steel: Characterization and Effect of Intercritical Annealing Parameters

2012

View full text Add to dashboard Cite

An ultrafine grained (UFG) ferrite/cementite steel was subjected to intercritical annealing in order to obtain an UFG ferrite/martensite dual-phase (DP) steel. The intercritical annealing parameters, namely, holding temperature and time, heating rate, and cooling rate were varied independently by applying dilatometer experiments. Microstructure characterization was performed using scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD). An EBSD data post-processing routine is proposed that allows precise distinction between the ferrite and the martensite phase. The sensitivity of the microstructure to the different annealing conditions is identified. As in conventional DP steels, the martensite fraction and the ferrite grain size increase with intercritical annealing time and temperature. Furthermore, the variations of the microstructure are explained in terms of the changes in phase transformation kinetics due to grain refinement and the manganese enrichment in cementite during warm deformation.

show abstract

“…[10] Because there is no additional process step required, BH could result in good shape fixability and improved dent and crash resistance without compromising the production cost. [9] In an earlier study of the BH mechanism, [15] it was proposed that the increase in the yield strength in the DP steels after treatment was caused by the presence of mobile dislocations formed in ferrite around the dispersed martensite islands during their formation. However, publications [16,17] have emphasized more complex mechanisms of BH in these steels as a result of the presence of the soft ferrite matrix and hard martensite phase in the microstructure and, in turn, the different behavior of phases during PS and the subsequent BH treatment.…”

mentioning

confidence: 99%

Transmission Electron Microscopy Characterization of the Bake-Hardening Behavior of Transformation-Induced Plasticity and Dual-Phase Steels

Timokhina

Hodgson

Pereloma

2007

Metall Mater Trans A

View full text Add to dashboard Cite

The effect of prestraining (PS) and bake hardening (BH) on the microstructures and mechanical properties has been studied in transformation-induced plasticity (TRIP) and dual-phase (DP) steels after intercritical annealing. The DP steel showed an increase in the yield strength and the appearance of the upper and lower yield points after a single BH treatment as compared with the as-received condition, whereas the mechanical properties of the TRIP steel remained unchanged. This difference appears to be because of the formation of plastic deformation zones with high dislocation density around the ''as-quenched'' martensite in the DP steel, which allowed carbon to pin these dislocations, which, in turn, increased the yield strength. It was found for both steels that the BH behavior depends on the dislocation rearrangement in ferrite with the formation of cell, microbands, and shear band structures after PS. The strain-induced transformation of retained austenite to martensite in the TRIP steel contributes to the formation of a complex dislocation structure.

show abstract

Process Factors for Cold-rolled Dual-phase Sheet Steels

Cited by 26 publications

References 0 publications

Formation of Ultrafine Grained Dual Phase Steels through Rapid Heating

Formation of Ultrafine Grained Dual Phase Steels through Rapid Heating

Microstructure Control during Fabrication of Ultrafine Grained Dual-phase Steel: Characterization and Effect of Intercritical Annealing Parameters

Transmission Electron Microscopy Characterization of the Bake-Hardening Behavior of Transformation-Induced Plasticity and Dual-Phase Steels

Contact Info

Product

Resources

About