Non-destructive texture measurement methods for centreless X-ray diffractometers in reverse modified Χ (CHI) mode

Conventional X-ray diffraction-based pole figure measurements have been carried on with dedicated instrument which are accompanied with certain limitations such as sample size, geometry, and no possibility for on-site measurements. These restrictions limit the availability of texture measurements to situations in which cutting a small sample from large parts is difficult or even not allowed at all. The present paper introduces new texture measurement method developed on mobile centreless X-ray diffractometers which are originally applied for residual stress measurements. The essence of this new method, named reverse modified mode is that it uses the data obtained by residual stress measurement to describe anisotropic characteristics, even to the determination of pole figure. Using this method, pole figures can be obtained with all the benefits of centreless diffractometers: no need for sample cutting, flexibility in case of large components with complex shapes, short measuring time and portability. The obtained pole figures are equivalent to the pole figures determined by conventional diffractometers. The presentation describes the measurement method and includes the validation with conventional pole figure measurements and provides instances of applications of the new technique

Kereszthengerelt nióbium nem konvencionális, roncsolásmentes textúra vizsgálata

Különböző mértékű fogyással kereszthengerelt, nagytisztaságú nióbium roncsolásmentes textúra vizsgálatát mutatjuk be. A kereszthengerlés célja a nióbium mélyhúzhatóságának javítása volt. A roncsolásmentes textúra vizsgálat során a különböző mértekig alakváltozott lemezek {110} {200} és {310} pólusábráit határoztuk meg robotkarra implementált központnélküli röntgendiffraktométer segítségével CHI módban. A mért eredményeket konvencionális, Euler bölcsővel rendelkező röntgendiffraktométerrel felvett pólusábrákkal validáltuk. Kísérletileg bebizonyítottuk, hogy a központnélküli diffraktométer CHI módban is alkalmas pólusábra felvételére, mivel a kapott eredmények a konvencionális módon felvett pólusábrákkal azonos eredményt adtak

Deformability Tests of Pure Niobium

research team at the University of Miskolc's Faculty of Materials Science and Technology has signed a cooperation agreement with the Geneva-based European Organization for Nuclear Research (CERN) for testing of the materials employed in the Crab Cavities will be installed in the next generation of the LHC (the so-called High Luminosity Large Hadron Collider – HL-LHC). At the University of Miskolc, high purity niobium rolling experiments were carried out in conventional (unidirectional) and cross-rolled manners in order to increase the deep drawability of the final sheet. The deformability of niobium was measured by Watts- Ford and compression tests. The microstructure and anisotropy (texture) results of the initial material and the straight-rolled products are reported

Non-destructive pole-figure measurements on workshop-made silver reference models of archaic objects

Based on the knowledge of crystallographic texture, the parameters of the metal-forming heat treatment of metallic objects can be reconstructed well when conventional technologies (e.g. rolling, deep drawing, etc.) are applied. The characterisation of texture has been possible only by using destructive techniques, apart from neutron diffraction. Recently, a non-destructive texture measurement method has been developed for centreless diffractometers, providing a new dimension to the examination of archaic objects. In the present study, two types of Stresstech G3R centreless diffractometer were used with this new method, which proved it to be applicable to both the tabletop and robotic arm-assisted versions of the diffractometer. Although the texture of archaic objects can be revealed using this method, the production of these objects cannot be directly deduced from the results, since their manufacturing steps are not identical to the metal-forming operations applied today. In this study, workshop-made silver reference samples were produced with the help of three silversmiths. Wrinkling, metal spinning and intermediate annealing were applied to the rolled silver sheet with the aim of making real-sized silver cups. The workshop-made reference cups were then subjected to non-destructive texture examinations. The results reveal the textures developed during the conventional manufacturing steps of silver cups. The obtained information greatly assists future research in understanding the pole figures of archaic objects and the reconstruction of their manufacturing technology

Sample cutting-free pole figure measuring method for centreless diffractometers in modified X mode

Conventional X-ray diffraction-based pole figure measurements are realized with dedicated equipment which are accompanied with certain limitations such as sample size, geometry, and no option for on-site measurements. These restrictions limit the availability of texture measurements in cases when sample cutting from the object of interest is not allowed. Within this manuscript, a novel method is described with which pole figure measurements can be realized using centreless diffractometers originally developed for residual stress measurements. The theoretical background of the proposed method is presented in detail. Instances of pole figures obtained with the described method are presented and compared to conventional ones. It was concluded that the presented method is applicable to measure pole figures in a reliable manner with all the benefits of centreless diffractometers: no need for sample cutting, large geometrical freedom and the possibility for on-site measurements

Novel applications of centreless X-ray diffractometers for non-destructive pole figure measurements

Centreless X ray diffractometers are specially designed for non-destructive residual stress measurements. The similarity between the X-ray diffraction-based stress and texture measurement methods led us to introduce a new method on non-destructive (sample cutting-free) stress measurement devices to studies on crystallographic texture. The method that determines texture characteristics from residual stress data has recently been introduced. Afterwards, a method with which pole figures (fully equivalent to conventionally measured pole figures) at high Bragg-angles can be constructed with centreless diffractometers were developed. The paper gives an illustration of the new methods’ utilization on the field of archaeometry. In that area, only non-destructive testing modes are permitted. In the case of archaeological finds, knowing the crystallographic texture assists to reconstruct the ancient process technology (hammering, rolling, annealing) that was applied during the manufacturing. The new methods are suitable to be used on valuable and unique objects both in the automotive industry, archaeometry and in the space applications

Estimation of Phase Ratio in Bulk, Textured TWIP/TRIP Steels from Pole Figures

The volume fraction of austenite (γ), ε martensite and α′ martensite is of key importance in the research of TWIP/TRIP steels. When mechanical loading is involved, the crystallographic texture also develops, which complicates X-ray diffraction-based phase ratio determination. The problem is more pronounced when only a couple, or only one Bragg-reflection can be measured. A solution for such cases is to determine the ratio of the phases based on the pole distribution function of a selected Bragg-reflection of the present phases. In this manuscript, this method is reconsidered for and applied to non-transmittable bulk specimens for the first time in the reflection mode of XRD pole figure measurements. First, the method was applied to a series of γ–α′ powder mixtures. The results were compared to those obtained by the Rietveld method. Afterwards, the technique was applied to strongly textured, bulk TWIP/TRIP steel specimens which were tensile tested at different temperatures. It was shown that the results of the presented method were close to those of the Rietveld technique in the case of powder mixtures. The results of the tensile-tested steels revealed that the α′ content increases with decreasing test temperatures, and the variation of the α′ ratio correlates very well with the ultimate tensile strength versus the temperature, confirming the contribution of the α′ content to the strength of TWIP/TRIP steels