Effect of Interlamellar Spacing on the Monotonic Behavior of C70 Pearlitic Steel

International audienceThe effect of interlamellar spacing on monotonic behavior of C70 pearlitic steel was investigated. Tensile tests under X-ray diffraction coupled with self-consistent model have been used to identify the role of interlamellar spacing on the ferrite plasticity parameters and residual stresses. It has been established that yielding of pearlite is controlled by ferrite critical shear stresses ( τc 0α) which is higher for the smaller interlamellar spacing. Moreover, the residual stress level in ferrite is higher for the largest interlamellar spacing under the same imposed total strain. Lattice strains, measured by synchrotron X-ray diffraction, show an elastic and plastic anisotropy of ferrite crystallites and high stresses in cementite which confirm the self-consistent model calculation

Scattering vector (h 2 k 2 l 2 ) Scattering vector (h 1 k 1 l 1 ) α α 2θ 2 t New developments of multireflection grazing incidence diffraction

Abstract. The multireflection grazing incident X-ray diffraction (MGIXD) is used to determine a stress gradient in thin surface layers (about 1-20 µm for metals). In this work two theoretical developments of this method are presented. The first procedure enables determination of c/a parameter in hexagonal polycrystalline materials exhibiting residual stresses. In the second method, the influence of stacking faults on the experimental data is considered. The results of both procedures were verified using X-rays diffraction. Introduction Multireflection grazing incidence X-ray diffraction (MGIXD) is a non-destructive method which allows performing an analysis of the heterogeneous stress field for different volumes below the surface of the sample. The penetration depth of X-ray radiation is well defined and does not change during experiment in a wide 2θ range for a given incidence angle

Study of Mechanical Behaviour of Polycrystalline Materials at the Mesoscale Using High Energy X-Ray Diffraction

International audienceOwing to its selectivity, diffraction is a powerful tool for analysing the mechanical behaviour of polycrystalline materials at the mesoscale, i.e. phase and grain scale. In situ synchrotron diffraction (transmission mode) during tensile tests and modified self-consistent elastoplastic model were used to study elastic and plastic phenomena occurring in polycrystalline specimens during deformation. The evolution of stress for grains which belong to different phases of duplex stainless steel and pearlitic steel was analyzed

Neutron diffraction study of elastoplastic behaviour of Al/SiCp metal matrix composite during tensile loading and unloading

International audienceIn this paper, we present a class of finite volume schemes for incompressible flow problems. The unknowns are collocated at the center of the control volumes, and the stability of the schemes is obtained by adding to the mass balance stabilization terms involving the pressure jumps across the edges of the mesh

Study of Micromechanical Behaviour of Two Phase Polycrystalline Materials Using Diffraction and Self Consistent Model

International audienceDiffraction methods for lattice strain measurement provide useful information concerning the nature of grains behaviour during elastoplastic deformation. The main advantage of the diffraction methods is the possibility of studying mechanical properties of polycrystalline materials separately in each phase and in groups of grains with a specific orientation. In this work we present application of the neutron and X-ray diffraction to study “in situ” deformation of two phase stainless steels during tensile loading. The experimental results are compared with self-consistent model

Neutron diffraction study of elastoplastic behaviour of Al/SiCp metal matrix composite during tensile loading and unloading

The aim of the present work is to study effects occurring during elatoplastic deformation and unloading of Al/SiCp metal–matrix composite material. We have measured lattice strains for both phases independently using two separated diffraction peaks (the 111 reflections of Al and SiC) during in situ tensile testing. Lattice strains were measured in the direction parallel to the applied load. The results were compared with an elastoplastic model in order to find parameters determining the plastic deformation of Al matrix (critical resolved shear stress and hardening parameter). We have found that during initial deformation relaxation of the thermal stresses occurs in both phases. Afterwards, the distribution of strains measured during the in situ test and unloading of the sample agree very well with self-consistent model prediction.</jats:p