Papers by Keyword: Free Surface Roughening

Abstract: The tensile deformation of NiTi alloy can proceeds in either homogeneous manner, or localized deformation via formation and propagation of macroscopic shear bands, that is commonly known as Lüders-like deformation. The high deformation strain within the localized deformed regions can result in the changes of surface characteristics of NiTi specimen. This paper studies the surface roughening effect associated with Lüders-like deformation of martensitic NiTi alloy, via surface characterization of polished surface and localized deformed region that consists of Lüders bands on tensile specimens, respectively. The surface roughness profile and roughness parameters of surface with Lüders bands are significantly different and higher as compared to the polished surface.

Abstract: In this study, we evaluated the characteristics of 3D finite element (FE) model considering material inhomogeneity for prediction of free surface roughening. Free surface roughening behavior can be observed by this model. The variation in material inhomogeneity parameter value has a strong correlation with the rate of increase in the surface roughness. macroscopic strength coefficient K value does absolutely not affect the rate of increasing surface roughness. Strain hardening sensitivity index n value slightly affects the free surface roughening behavior. The true stress – true strain curve of the inhomogeneous FE model is in good agreement with those of the homogeneous FE model and the experimental result. As a result, the characteristics evaluation of suggested model considering material inhomogeneity is conducted.

Abstract: To understand the free surface roughening phenomena of polycrystalline metals, the surface roughening behaviors of three kinds of metal sheets were investigated under uniaxial tension. The materials used were AZ31 magnesium alloy, SPFC 590Y steel, and A5052-O aluminum alloy. In the in-situ observation of surface roughening for AZ31 magnesium alloy, it seemed that the surface of each grain roughened independently and the roughness increases with increasing plastic strain. In contrast to A5052-O and SPFC, the anisotropy of free surface roughening was observed for AZ31 magnesium alloy. Compared with planar anisotropy , the microscopic anisotropy of surface roughening is not related to . In AZ31 magnesium alloy, the anisotropy of surface roughening arises and, instead of the r-value, another parameter is needed to evaluate the anisotropy of free surface roughening.