Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Pushkareva, Irina; Allain, Sébastien; Scott, Colin; Redjaïmia, A.; Moulin, Antoine

doi:10.2355/isijinternational.isijint-2015-186

Cited by 52 publications

(23 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When the strength discrepancy decreases, the strain partitioning decreases too and micro-cracks tend to nucleate within one of the phases. 19,35) This is in very good agreement with the crack observations in Fig. 11.…”

Section: Discussionsupporting

confidence: 90%

“…It has been widely reported, particularly for DP steels, that the stretch-flange-formability tends to increase when the strength discrepancies between the different phases in the material decreases. [17][18][19][20][21][22]35) The present study confirms clearly this statement: the best stretch-flange-formability is found for a single phase material, i.e. the Q&T microstructure.…”

Section: Discussionsupporting

confidence: 82%

See 1 more Smart Citation

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

et al. 2018

View full text Add to dashboard Cite

Quenching and Partitioning (Q&P) has been proposed as a novel heat treatment to produce cold rolled sheets with excellent strength and sufficient formability for cold stamping. The impact of Q&P processing on microstructure and tensile properties has been extensively studied in contrast to the lower attention devoted to its effect on stretch-flange-formability. In this study, the stretch-flange-formability of Q&P microstructures is investigated by means of hole expansion tests carried out on punched holes. The balance between tensile properties and hole expansion ratios (HER) is discussed and compared to three model microstructures: biphasic dual-phase (DP), single phase quenched & tempered (Q&T) and quenched & austempered (QAT). It is shown that Q&P microstructures exhibit a better combination of tensile ductility and stretch-flange-formability than fully martensitic (excellent HER but poor tensile ductility) and austempered microstructures (good ductility but poor HER). The study of the impact of the Q&P parameters demonstrates that stretch-flange-formability is further promoted by choosing low quench temperatures and long partitioning times. The hole expansion properties are linked to the hardness gradients in the microstructure, evaluated by nanohardness mapping. The narrower nanohardness distribution in the Q&P microstructure leads to better hole expansion ratios compared to bainitic microstructures obtained by austempering, where the presence of hard M/A blocks is unavoidable.

show abstract

Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 82%

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Generally, mechanical testing is preceded and/or followed by microstructural investigations in order to get the structure-property-processing relationships [4,5,6,7]. In situ characterization provides more useful data for a more realistic theoretical modeling, which allows for predicting the mechanical performance of components.…”

Section: Introductionmentioning

confidence: 99%

In Situ Macroscopic Tensile Testing in SEM and Electron Channeling Contrast Imaging: Pencil Glide Evidenced in a Bulk β-Ti21S Polycrystal

et al. 2019

View full text Add to dashboard Cite

In this paper, we report the successful combination of macroscopic uniaxial tensile testing of bulk specimen combined with In situ dislocation-scale observations of the evolution of deformation microstructures during loading at several stress states. The dislocation-scale observations were performed by Accurate Electron Channeling Contrast Imaging in order to follow the defects evolution and their interactions with grain boundaries for several regions of interest during macroscopic loading. With this novel in situ procedure, the slip systems governing the deformation in polycrystalline bulk β-Ti21S are tracked during the macroscopic uniaxial tensile test. For instance, curved slip lines that are associated with “pencil glide” phenomenon and tangled dislocation networks are evidenced.

show abstract

“…For instance, the influence of volume fraction of martensite on the impact absorbed energy has been evaluated. [2][3][4][5][6] However, it is difficult to determine the effect of volume fraction because the character of martensite depends on its carbon content, which changes with the volume fraction. In addition, the component characteristics, such as morphology 7,8) and local strength, 4,9) affect the impact property.…”

Section: Introductionmentioning

confidence: 99%

Effect of Pearlite Volume Fraction on Two-step Ductile to Brittle Transition in Ferrite + Pearlite Structure Steel Sheets

Kawata

Umezawa

2019

ISIJ Int.

View full text Add to dashboard Cite

Multi structural steels exhibit high strength and good formability; however, their performance depends on the volume fraction of the secondary phase. In our previous study, ferrite + pearlite structural steel sheet showed the characteristic two-step ductile-to-brittle transition (DBT) with decreasing temperature, and the absorbed energy curve exhibited a distinct middle shelf. In this study, we evaluated the effect of pearlite volume fraction (V P) on the DBT behavior by the Charpy impact test with sub-size specimens. For specimens without pearlite, the absorbed energy directly dropped from the upper shelf to the lower shelf with decreasing temperature. For samples with 2-3% pearlite, the absorbed energy corresponding to the transition temperature range was dispersed between the two shelves, and the transition behavior seemed to be the typical DBT behavior. When V P was increased to 21%, the absorbed energy just above the transition-finish temperature became stable at a middle level between the two shelves; thus, the existence of a distinct middle shelf was confirmed. Although the transition-start temperature increased with increasing V P , V P did not affect the transition-finish temperature and the absorbed energy at the middle shelf. These results were analyzed with a simple model based on the Yoffee diagram.

show abstract

Relationship between Microstructure, Mechanical Properties and Damage Mechanisms in High Martensite Fraction Dual Phase Steels

Cited by 52 publications

References 30 publications

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

In Situ Macroscopic Tensile Testing in SEM and Electron Channeling Contrast Imaging: Pencil Glide Evidenced in a Bulk β-Ti21S Polycrystal

Effect of Pearlite Volume Fraction on Two-step Ductile to Brittle Transition in Ferrite + Pearlite Structure Steel Sheets

Contact Info

Product

Resources

About