Unraveling the Initial Microstructure Effects on Mechanical Properties and Work-Hardening Capacity of Dual-Phase Steel

Dehghanian

2020

Mater. Res. Express

Self Cite

Systematic works on the effect of grain size on the corrosion resistance of low carbon steel are scant. In the present work, a spectrum of grain sizes was obtained by simple heat treatment routes in a typical low-carbon steel. It was revealed that two distinct stages for the dependency of corrosion current density (i corr ) on the grain size exist. Above a limiting average grain size of ∼22 μm, i corr decreased slowly with increasing grain size. However, below this limiting value, i corr increased rapidly, which was related to the increased density of grain boundaries as interpreted by theoretical calculation of number of grains per unit area. Conclusively, a grain size of ∼22 μm (ASTM grain-size number of 8) was considered to be an optimum value according to the mechanical and corrosion standpoints.

Section: Resultssupporting

confidence: 80%

Effect of grain size on the corrosion resistance of low carbon steel

Soleimani

Dehghanian

2020

Mater. Res. Express

Self Cite

“…For obtaining the slope, the central difference approach based on

n true|_{i} = {\ln σ_{i + 1}^{} - \ln σ_{i - 1}^{}} / {\ln ϵ_{i + 1} - \ln ϵ_{i - 1}}

was utilized. The modified Crussard‐Jaoul analysis was also used for studying the work‐hardening behavior, where it is based on the Swift formula expressed as

ϵ = A + B σ^{p}

, where A , B , and p are constants. Therefore,

σ = \sqrt[p]{(ϵ - A) / B}

, then

d σ / d ϵ = σ / (p (ϵ - A))

, and finally

\ln (d σ / d ϵ) = (1 - p) \ln σ - \ln (p B)

.…”

Section: Methodsmentioning

confidence: 99%

“…Different techniques have been used for grain refinement of DP steels. The intercritical annealing of cold‐worked martensite or ultrafine grained (UFG) ferrite‐carbide aggregate, fast and ultrafast heating, ultrafast cooling (UFC), Deformation‐induced ferrite transformation (DIFT), and severe plastic deformation have been recently practiced. Most of these techniques are based on prior deformation and need rolling facilities or more complicated and expensive deformation routes.…”

Section: Introductionmentioning

confidence: 99%

Refinement of Banded Structure via Thermal Cycling and Its Effects on Mechanical Properties of Dual Phase Steel

Ghaemifar

2018

steel research int.

Self Cite

The microstructural refinement by thermal cycling and its effects on the enhancement of mechanical properties and work-hardening response of a typical C-Mn dual phase (DP) steel having the banded ferritic-martensitic morphology is evaluated. It is revealed that the band spacing is reduced by decreasing austenitization temperature and applying thermal cycles to intercritical region, where a saturated spacing will be reached. This results in the enhancement of work-hardening capacity of DP steels as demonstrated based on the instantaneous (incremental) work-hardening rate exponents, modified Crussard-Jaoul analysis, and evaluating the yield ratio after tensile tests. These observations justify the potential of this simple heat treatment route for microstructural control of DP steels. Figure 8. a) Dependence of UTS and total elongation on band spacing and b) Dependence of yield ratio and UTS-YS on band spacing.www.advancedsciencenews.com www.steel-research.de steel research int. 2018, 89, 1700531

“…After intercritical annealing at 735 8C, the martensite particle sizes are much finer than that produced from full annealed sample (DP1) and they are uniformly dispersed in the microstructure (denoted as DP3), Figure 3. This good distribution leads to a better combination of mechanical properties [11,15,18,28,29], where both DP1 and DP3 steels have total elongation of 35 % but the tensile strength of DP3 is 1.14 times that of DP1, Figure 3. Again by increasing the intercritical annealing temperature from 735 8C to 800 8C (DP4), the strength enhances from 647 MPa to 1091 MPa, Figure 3.…”

Section: The Initial Quenched Microstructurementioning

confidence: 99%

Enhancement of work‐hardening behavior of dual phase steel by heat treatment

Nasiri

Materialwissenschaft Werkst

2018

The work‐hardening response and mechanical properties of dual phase steels originated from different initial microstructures under low and high martensite volume fractions were investigated using a typical carbon‐manganese steel. The modified Crussard‐Jaoul analysis was used for studying the work‐hardening stages and the deformation behavior of ferrite and martensite. It was revealed that the initial martensitic microstructure before intercritical annealing is much better than the full annealed banded ferritic‐pearlitic and spheroidized microstructures in terms of work‐hardening capacity and strength‐ductility trade off. By increasing the amount of martensite, via intercritical annealing at higher temperatures, the ductility decreased but the tensile toughness of dual phase steels increased toward reaching the domain of extra‐advanced high‐strength steels due to the enhancement of work‐hardening rate.