Influence of martensite volume fraction and hardness on the plastic behavior of dual-phase steels: Experiments and micromechanical modeling

Lai, Qingquan; Brassart, Laurence; Bouaziz, Olivier; Gouné, Mohamed; Verdier, M.; Parry, Guillaume; Perlade, Astrid; Bréchet, Y.; Pardoen, Thomas

doi:10.1016/j.ijplas.2015.09.006

Cited by 92 publications

(49 citation statements)

References 56 publications

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“…In addition, the back stress work hardening will also help with preventing necking during tensile testing, thus improving ductility [11,16].\ Steel composed of different phases is a kind of natural HSMs, in which the phases have different mechanical properties [17][18][19][20][21]. For example, the commercial DP steels, generally containing 20-30 vol% hard martensite phase embedded in the soft ferrite matrix [22][23][24], have been paid continuous attention due to their attractive mechanical properties, including the strength-ductility synergy, good formability and low production cost [25][26][27][28]. Compared with other HSMs reported in the literature [4,5,9,10], the production of DP steels is more flexible, involving the interplay of alloy composition and the controlled genesis of microstructure [25].…”

Section: Introductionmentioning

confidence: 99%

A high-strength heterogeneous structural dual-phase steel

et al. 2019

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The strengthening and ductilization of steels are of great importance to weight reduction of vehicles. In this work, the strength-ductility synergy of dual-phase (DP) steels was obtained by properly tailoring the structural heterogeneity, including the distribution and fraction of constituent phases. It was demonstrated that heterogeneous structural DP steels with high volume fraction of martensite (from 64 to 83%) led to a good combination of strength and ductility. Compared with the cold-rolled sheets, the tensile strength and uniform elongation of heterogeneous DP steel increased by 700 MPa (from 1.06 to 1.76 GPa) and 2.7% (from 1.3 to 4%), respectively. The contributions from back stress and effective stress were analyzed by cyclic loading-unloading experiments. The underlying deformation mechanism was discussed based on the results of mechanical test and microstructure observation.

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Section: Introductionmentioning

confidence: 99%

A high-strength heterogeneous structural dual-phase steel

et al. 2019

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“…The yield strength (YS) and ultimate tensile strength (UTS) was decreased, while uniform elongation (UE) and total elongation (TE) was increased with annealing time. It is generally considered that YS of dual‐phase steels is determined by both soft phase and hard phase . Moreover, the change in YS is consistent with that of martensite or macrohardness hardness.…”

Section: Resultsmentioning

confidence: 92%

Structure‐Property Relationship in a Micro‐laminated Low‐Density Steel for Offshore Structure

Zhang

et al. 2019

steel research int.

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A low‐density steel (7.5 g cm−3) steel produced by direct‐quenching and intercritical annealing (IA) process is designed for offshore structure. The microstructure, mechanical properties, and corrosion resistance of steels are studied. It is found that after IA process, the microstructure is composed of micro‐laminated delta‐ferrite, tempered martensite, and reverted austenite. Two stage partitioning processes, the reheating process prior to rolling, and IA process lead to enrichment of C, Mn, and Ni elements in the reverted austenite. The enrichment of alloying elements stabilized austenite, and the retained austenite content is up to 18%. The growth of reverted austenite at lath‐lath interface is simulated by DICTRA software, and the results show that the growth of reverted austenite are controlled by diffusion of alloying elements. The ductility and toughness has a strong relationship with content of retained austenite. The mechanical properties are excellent with high yield strength (>620 MPa) and high total elongation (>40%). The experimental steel has excellent resistance to marine atmospheric corrosion, because of enrichment of Al and Ni in the rust layer, that leads to a compact layer. In addition, the partitioning of Al and Ni into different phase, promotes the corrosion resistance of rust layer.

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“…[38] decreases the uniform elongation [38]. In Figure 2.5, at given tensile strength, the uniform elongation of fine-grained steels is better [38]. Thus, the ductility of dual-phase steels is also controlled by grain sizes.…”

Section: Mechanical Properties Of Dual Phase Steelsmentioning

confidence: 90%

“…These unique properties are controlled by volume fraction of martensite, ferrite grain sizes, and fine precipitates in the ferrite matrix [1]. [38] decreases the uniform elongation [38]. In Figure 2.5, at given tensile strength, the uniform elongation of fine-grained steels is better [38].…”

Section: Mechanical Properties Of Dual Phase Steelsmentioning

confidence: 99%

Processing, Microstructures and Properties of Ultra-High Strength, Low Carbon and V-Bearing Dual-Phase Steels Produced on Continuous Galvanizing Lines

Wu¹,

DeArdo²

2018

Contributed Papers From MS&T17

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One of the most popular elements in weight reduction programs in the automotive industry is high strength zinc coated dual-phase steel produced on continuous hot dipped galvanizing lines. The high strength is needed for mass reduction, while the protective zinc coating is needed to prevent corrosion of the thin gage cold rolled steel. The present study was aimed to explore an optimized way to produce such dual-phase steels with ultra-high tensile strength (UTS > 1280MPa), good global ductility (TE > 18%), excellent local ductility (sheared-edge ductility, HER > 40%) and products of UTS × TE > 22000 MPa × %, conforming to data of AHSS Generation III steel. A steel of this kind is referred to as a third-generation advanced high strength steel. By altering chemical compositions (0.15wt.% carbon), pre-annealing conditions (different hot band coiling temperatures and cold reductions), annealing conditions (different intercritical annealing temperatures) and annealing paths (standard galvanizing or supercool processing), this study set out to investigate the effects of these factors on the microstructures and mechanical properties of dual-phase steels. Results showed that the stored energy of cold rolled steel with 0.15wt.% carbon was much higher than that of carbon containing 0.1wt.% carbon, generating numerous lattice defects during deformation and providing more driving force for formation of austenite and v recrystallization of ferrite during the intercritical anneal. In addition, it was found that the volume fraction of martensite increased with the combination of low coiling temperature, high cold reduction, and high annealing temperature, thereby increasing the tensile strength. Furthermore, the microstructural analysis and tensile testing results and showed that the tensile strength of dual-phase steel with 0.15Wt.% carbon, combined with the ultrafine microstructures (average ferrite grain sizes reached 1-2µm) could approach 1300MPa without loss of ductility and with hole expansion ratios, in some cases, reaching 35%. Since the relative hardness of the hard martensite and soft ferrite is important in controlling sheared-edge ductility, the nanohardness results of these phases were measured. It was revealed that the martensite hardness decreased with increasing volume fraction, at a given carbon content, indicating the tensile strength was independent of the martensite hardness. Other mechanical properties, such as yield strength, YS/UTS ratio, hardness and work hardening behavior, of dual-phase steels controlled by the factors mentioned above were correlated to the microstructural features. The hypothesis that the bulk carbon content would be a major factor in controlling the strength of these steels was vindicated by the results of this study.

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Influence of martensite volume fraction and hardness on the plastic behavior of dual-phase steels: Experiments and micromechanical modeling

Cited by 92 publications

References 56 publications

A high-strength heterogeneous structural dual-phase steel

A high-strength heterogeneous structural dual-phase steel

Structure‐Property Relationship in a Micro‐laminated Low‐Density Steel for Offshore Structure

Processing, Microstructures and Properties of Ultra-High Strength, Low Carbon and V-Bearing Dual-Phase Steels Produced on Continuous Galvanizing Lines

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