Synergistic effects of holding time at intercritical annealing temperature and initial microstructure on the mechanical properties of dual phase steel

Jamei, Fatemeh; Mirzadeh, Hamed; Zamani, Mehran

doi:10.1016/j.msea.2019.02.052

Cited by 54 publications

(26 citation statements)

References 44 publications

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“…Therefore, a decrease in hardness with the increasing holding time is related to a decrease in the amount of martensite. Conversely, as shown in Figure , for the IA samples, hardness increases during holding at the IA temperature due to partial austenitization (formation of austenite from pearlite and then from the surrounding ferrite phase), and the resulting increase in the martensite fraction after quenching can be deduced by comparing Figure h,i. The hardness reaches the same plateau at ≈5 min.…”

Section: Resultsmentioning

confidence: 92%

Unraveling the Effect of Martensite Volume Fraction on the Mechanical and Corrosion Properties of Low‐Carbon Dual‐Phase Steel

Soleimani

Mirzadeh

Dehghanian

2019

steel research int.

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The effect of martensite volume fraction on the mechanical and corrosion properties of low-carbon dual-phase steel is studied based on both step quenching (SQ) and intercritical annealing (IA) routes. For SQ samples, hardness and ultimate tensile strength decrease with increasing holding time at the intercritical temperature and reach a plateau, which is related to the decrease in the amount of martensite during annealing. Conversely, for the IA samples, hardness increases during holding at the intercritical temperature due to austenitization and reaches the same plateau. At a same martensite volume fraction, the work-hardening behavior of SQ samples is better than IA samples, which is related to both the finer grain size and smaller martensite islands in the former. At low martensite fractions, the corrosion properties are comparable with the asreceived ferritic-pearlitic sample. It is revealed that by decreasing the volume fraction of martensite in SQ samples, the corrosion current density (i corr ) decreases almost linearly, and at martensite content of zero, it reaches the i corr of the fully ferritic microstructure. The latter is found to be lower than the i corr of the as-received sample. Therefore, the real effect of martensite on corrosion properties is unraveled for the first time.

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Section: Resultsmentioning

confidence: 92%

Unraveling the Effect of Martensite Volume Fraction on the Mechanical and Corrosion Properties of Low‐Carbon Dual‐Phase Steel

Soleimani

Mirzadeh

Dehghanian

2019

steel research int.

Self Cite

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“…Tensile testing was carried out at room temperature by a computerized testing machine at the constant cross‐head speed of 1 mm min −1 to obtain engineering stress ( S )–engineering strain ( e ) curves. The values of work‐hardening rate were determined based on

d σ / d ε |_{i} = {σ_{i + 1} - σ_{i - 1}} / {ε_{i + 1} - ε_{i - 1}}

, where

σ = S (1 + e)

and

ε = \ln (1 + e)

are true stress and true strain (logarithmic strain), respectively. The instantaneous (incremental) work‐hardening exponent ( n ) based on the Hollomon equation (

σ = k ε^{n}

\ln σ = \ln k + n \ln ε

) was also considered.…”

Section: Methodsmentioning

confidence: 99%

Effects of Grain Size on Mechanical Properties and Work‐Hardening Behavior of AISI 304 Austenitic Stainless Steel

Naghizadeh

Mirzadeh

2019

steel research int.

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120

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Grain size effects on the properties of AISI 304 austenitic stainless steel are studied. Yield stress (YS) and ultimate tensile strength (UTS) increased with decreasing grain size (Hall–Petch law) while the difference between YS and UTS decreased. Three distinct stages for work‐hardening rate are identified: I) initial rapid fall until reaching a minimum value, II) subsequent rise to a maximum due to the transformation‐induced plasticity (TRIP) effect, which is found to enhance by increasing grain size, and III) final fall until the onset of necking. More in‐depth analysis on the mechanical stability of austenite reveals that for below‐average grain size of ≈50 μm, by decreasing grain size, the TRIP effect diminishes; whereas for grain size larger than ≈50 μm, by increasing grain size, the TRIP effect becomes less pronounced. Due to the strong TRIP effect, high incremental work‐hardening exponents (n‐values of higher than 0.8) and low‐yield ratios (smaller than 0.5) are observed. It is also found that when the average grain size increases, the tensile toughness and the size and depth of dimples increase. The latter is responsible for the tardiness of the microcavity coalescence, which is indicative of high ductility of this austenitic alloy.

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“…The heterogeneities of the materials at various scales have received much attention due to the potential of attaining impressive mechanical properties. The relevant heterogeneities include the gradient structure [4], bimodal structure [5], dual-phase (DP) steel [6][7][8], heterogeneous lamella structure [9] and nanodomained structure [10]. These materials all have a dramatic difference in strength between different domains, while the sizes and geometry of the domains could be in the range of micrometers to millimeters, and have been defined as heterogeneous structural materials (HSMs) [11].…”

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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Synergistic effects of holding time at intercritical annealing temperature and initial microstructure on the mechanical properties of dual phase steel

Cited by 54 publications

References 44 publications

Unraveling the Effect of Martensite Volume Fraction on the Mechanical and Corrosion Properties of Low‐Carbon Dual‐Phase Steel

Unraveling the Effect of Martensite Volume Fraction on the Mechanical and Corrosion Properties of Low‐Carbon Dual‐Phase Steel

Effects of Grain Size on Mechanical Properties and Work‐Hardening Behavior of AISI 304 Austenitic Stainless Steel

A high-strength heterogeneous structural dual-phase steel

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