Lattice Strain and Strain Evolution in Hydrogen-Implanted Materials: The Roles of Mechanical Properties and Hydrogen Diffusion

To explore the effect of neodymium (Nd) on the deformation mechanisms of Mg–Zn alloys, texture and lattice strain developments of hot-rolled Mg–Zn (Z1) and Mg–Zn–Nd (ZN10) alloys were investigated using in situ synchrotron diffraction and compared with elasto-viscoplastic self-consistent simulation under tensile loading. The Nd-containing ZN10 alloys show much weaker texture after hot rolling than the Nd-free Z1 alloy. To investigate the influence of the initial texture on the texture and lattice strain evolution, the tensile tests were carried out in the rolling and transverse direction. During tension, the {002}<100> texture components develop fast in Z1, which was not seen for ZN10. On the other hand, <100> fiber // loading direction (LD) developed in both alloys, although it was faster in ZN10 than in Z1. Lattice strain investigation showed that <101> // LD-oriented grains experienced plastic deformation first during tension, which can be related to basal slip activity. This was more apparent for ZN10 than for Z1. The simulation results show that the prismatic slip plays a vital role in the plastic deformation of Z1 directly from the beginning. In contrast, ZN10 plastic deformation starts with dominant basal slip but during deformation prismatic slip becomes increasingly important.

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Crystal Plasticity Analysis of Stress Partitioning Mechanisms and Their Microstructural Dependence in Advanced Steels

Journal of Applied Mechanics ◽

10.1115/1.4029552 ◽

2015 ◽

Vol 82 (3) ◽

Cited By ~ 16

Author(s):

Chao Pu ◽

Yanfei Gao

Keyword(s):

Crystal Plasticity ◽

Lattice Strain ◽

Martensite Phase ◽

Geometric Constraints ◽

High Yield ◽

Uniaxial Tensile ◽

Hard Phase ◽

Ductile Phase ◽

Strain Evolution ◽

Stress Partitioning

Two-phase advanced steels have an optimized combination of high yield strength and large elongation strain at failure, as a result of stress partitioning between a hard phase (martensite) and a ductile phase (ferrite or austenite). Provided with strong interfaces between the constituent phases, the failure in the brittle martensite phase will be delayed by the surrounding geometric constraints, while the rule of mixture will dictate a large strength of the composite. To this end, the microstructural design of these composites is imperative especially in terms of the stress partitioning mechanisms among the constituent phases. Based on the characteristic microstructures of dual phase and multilayered steels, two polycrystalline aggregate models are constructed to simulate the microscopic lattice strain evolution of these materials during uniaxial tensile tests. By comparing the lattice strain evolution from crystal plasticity finite element simulations with advanced in situ diffraction measurements in literature, this study investigates the correlations between the material microstructure and the micromechanical interactions on the intergranular and interphase levels. It is found that although the applied stress will be ultimately accommodated by the hard phase and hard grain families, the sequence of the stress partitioning on grain and phase levels can be altered by microstructural designs. Implications of these findings on delaying localized failure are also discussed.

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