Papers by Keyword: Sin₂-Ψ Method

Abstract: Premature collapse in terms of cohesive damage of PVD-coated carbide cutting tools often results in a time and cost consuming immediate interrupt of the cutting process. It is assumed that the residual stress state of the composite coating – substrate in combination with external loads during tool use is responsible for cohesive damage. The X-ray diffraction methods sin2 and scattering vector are applied for determination of the residual stress depth distribution in the coating and the substrate’s subsurface. Investigations of the residual stress state of commercial PVD-coated carbide cutting tools are presented. It is determined to what extent the single process steps during tool manufacturing are responsible for the final residual stress state of the PVD-coated tool. Furthermore the meaning of the PVD-coating process for the substrate’s residual stress state is investigated. Moreover, possibilities of controlling the residual stress state of the substrate by changing process variables of selected process steps are analyzed.

Abstract: The results of residual stresses in biocompatible cast Ni-Cr alloys-ceramics joints with an intermediate layer with thickness of about 10μm are discussed. To the experiment were used specimens with dimensions of 45×3×10 mm and 45×4×10 mm made of Cr-Ni alloys-ceramics joint both with and without of application of an intermediate layer. The examinations were carried out by means of metallographical microscope, testing machine and X-ray diffractometer. The measurement of residual macrostresses was carried out by using sin2ψ method. The obtained experimentally values of residual macrostresses are in good agreement with results of numerical simulation performed by means of FEM ANSYS package. The researches have been shown that application of an intermediate ceramics layer influence on increase of strength properties of Ni-Cr alloys-ceramics joints.

Abstract: This paper focuses on the study of the superelastic behavior associated to the stress induced martensite transformation in a Cu-12.5%Al-0.5%Be [wt. %] shape memory alloy. Neutron diffraction was used to track the evolution of stress in the (β1) austenitic phase during the onset of the stress-induced martensite phase change. A thin flat and a cylindrical specimen was analyzed, allowing us firstly to evaluate the stress evolution in the austenite phase during martensitic transformation with laboratory X-ray and neutron diffraction and secondly to compare differences between methods (sin2ψ, principal stress) for in-situ neutron diffraction experiments.

Abstract: This paper reports experimental characterisation of stress heterogeneities in a French RPV bainitic steel (16MND5) determined by X-Ray diffraction during in-situ tensile testing at low temperature (until –150°C). Results are compared successfully to simulation results, obtained by post-processing of Finite Elements computations of realistic 3D aggregates.

Abstract: The non-destructive and phase selective determination of residual stresses caused by material processing (such as welding) in polycrystalline samples is usually performed by diffraction methods. In order to obtain information about stress fields at high spatial resolution with conventional methods, for example with micro beam techniques, the sample needs to be scanned in a very time consuming manner. A much faster method is the simultaneous investigation of a larger area using position sensitive diffractometry. This method was used for the analysis of the residual stress distribution in laser beam welded thin (2 mm and 3 mm) magnesium sheets.