Determination of Yield Stress in a Duplex Steel with α + γ Lamellar Structure
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Yield stress σy is evaluated in a duplex steel with α + γ lamellar structure by calculating the stress for the propagation of pile-up dislocations in one phase into another phase. Effective grain size of a lamella is determined to calculate the contribution of each boundary of a lamella to dislocation pile-up. Comparison of stresses required to drive α-to-γ and γ-to-α propagations of pile-up dislocations suggests that α + γ lamellar structure yields by propagation of pile-up dislocations in α lamella to γ lamella. σy of α + γ lamellar structure is calculated as the sum of friction stress σoα of α and the stress component Δσγ for yielding of γ lamella at the effective grain size dα,eff of α lamella. The calculated results explain better to the experimental σy than do results calculated using rule of mixture.
This work was partially supported by the Technology Development Project (Project numbers: 4.0014548) from POSCO. J.-H. Kang was supported by the Fundamental Research Program of the Korea Institute of Materials Science (PNK5570).
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