Deformation Behavior Of Iron Research Articles

Micromechanical Analysis for Iron-Based Composites Under Large Deformations

A micromechanical analysis under large deformations for iron-based composites is introduced to predict the deformation behavior of iron (Fe)-copper (Cu) composites. In particular, pure Fe, pure Cu, Fe-17 wt. $$\%$$ Cu, and Fe-83 wt. $$\%$$ Cu are studied. In Fe-Cu composites, Cu is a soft-phase material. Hence, it undergoes a large deformation. Fe being the hard phase material shows elevated stresses. Because of the heterogeneity in the microstructure of Fe-Cu composites, the micromechanical model enables the capture of the flow behavior of Fe-Cu polycrystals. Both Fe and Cu constituents are rate-dependent elasto-viscoplastic materials. Hence, they are formulated in the framework of large deformations. The reliability of the prediction of flow behavior is investigated by comparing the numerical model (Taylor approach) and experiments.

1017 鉄中炭素挙動と炭素が鉄の力学的特性に与える影響の原子レベル解析(OS10. 電子・原子・マルチシミュレーションに基づく材料特性評価,OS11. 材料の組織・強度に関するマルチスケールアナリシス 合同ポスターセッション,オーガナイズドセッション講演)

1017 鉄中炭素挙動と炭素が鉄の力学的特性に与える影響の原子レベル解析(OS10. 電子・原子・マルチシミュレーションに基づく材料特性評価,OS11. 材料の組織・強度に関するマルチスケールアナリシス 合同ポスターセッション,オーガナイズドセッション講演)

Evolution of dislocation structures and deformation behavior of iron at different temperatures: Part I. strain hardening curves and cellular structure

The deformation behavior of iron has been investigated at different temperatures by means of tension tests. There exist two temperature ranges for deformation. In the low-temperature range(T < 293 K), the flow stress σ, the work-hardening rate θ at e = 0.06, and the yield stress σy decrease with increasing temperature, but in the higher temperature range(T ≥: 293 K), σ and θ at the same strain increase while σy decreases more slowly. The change of dislocation density, with temperature, ate = 0.06 exhibits the same tendency as that of the flow stress. The strainhardening rates decrease almost linearly with increasing stress up to necking in the low-temperature range, except the initial strain range. At the higher temperature range, the hardening rates decrease linearly with stress only at the early stage of deformation, but above certain strains, the decreases become more gradual; that is, the G-cr curves deviate from the linear region. The evolution of dislocation structure has also been observed by transmission electron microscopy (TEM). The results show that a substructural transition takes place in the nonlinear range of G-cr curves. In the linear decreasing region of strain-hardening curves, the deformation is controlled by the uniformly distributed dislocations or cell multiplication prevails. However, in the nonlinear region of G-cr curves, cell multiplication seems to be balanced by cell annihilation.

Evolution of dislocation structures and deformation behavior of iron at different temperatures: Part II. dislocation density and theoretical analysis

The evolution of dislocation density in iron deformed at 173 K and at room temperature has been examined by transmission electron microscopy (TEM). At room temperature, the dislocation density in the cell walls increases as the deformation progresses up to large strains, whereas in cell interiors, the density evolves toward a saturation value. A linear relationship exists between the flow stress and the square root of total dislocation density both at 173 K and room temperature. The dependence of deformation behavior on the evolution of dislocation structures is discussed in terms of a model considering the dislocation distribution during deformation. Comparison of the calculated result using this model with the experimental curve at room temperature gives excellent agreement. The changes of deformation behaviors at different temperatures can be described by the effect of temperature on the evolution of dislocation distribution.

Effects of hydrogen on deformation behavior of iron with different dislocation structures

Effects of hydrogen on deformation behavior of iron with different dislocation structures