Determination of the residual stress tensor in textured zirconium alloy by neutron diffraction

Results of neutron diffraction studies of crystallographic texture and residual stress tensor components in cold-worked and annealed cylindrical components made from E-110 zirconium alloy are presented. Those components are used as plugs in the fuel elements of the VVER-type reactors; the resident residual stresses influence the durability and safety of the fuel elements. The experiments were carried out on the neutron diffractometers at Dubna (the IBR-2 pulsed reactor) and Berlin Helmholtz–Zentrum (the BER II research reactor). It is shown that the samples have fiber texture that is changed considerably with annealing. The type I residual stress tensors for both samples were calculated by the BulkPathGEO model. The cold worked component has 136–166 MPa tensile residual stress in the radial direction and zero stress along the axial direction. Residual stress values in the annealed component are close to zero.     

NDE of residual stress in uranium by means of neutron diffraction

In the present work, a neutron diffraction technique for the nondestructive measurement of subsurface residual stress gradients in textured metallurgical samples is described. The technique is applied to the characterization of stresses in an aluminum calibration sample and to two depleted uranium-alloy cylinders of differing thermo-mechanical histories. The results confirm the accuracy of the technique and that neutron diffraction now appears to be the only technique by which nondestructive characterization of subsurface residual stress in uranium is possible.     

Residual stresses and tetragonal phase fraction characterisation of corrosion tested Zircaloy-4 using energy dispersive synchrotron X-ray diffraction

To improve the understanding of the oxidation mechanism in zirconium alloys for fuel clad applications, detailed residual stress and phase fraction analysis was carried out for the oxides formed on Zircaloy-4 after autoclave exposure at 360 °C for various times by means of synchrotron X-ray diffraction. In a post-transition sample (220 days), significant stress variation through the oxide thickness was found for the monoclinic phase in individual oxide layers, with maximum in-plane compressive stresses located towards the metal–oxide interface and a discontinuity in the residual stress profile. The depth of this discontinuity matched well with the depth at which electron microscopy analysis showed an interface between two distinct oxide layers. Analysis of the tetragonal phase with exposure time demonstrated changes of the total volume of tetragonal phase before and during transition. These observations are put into the context of residual stress evolution presented previously, to provide further insight into the importance of phase transformations and residual stresses in determining the corrosion kinetics of Zr alloys.     

Modeling of weld residual stresses in core shroud structures

This paper presents a computational model to predict residual stresses in a girth weld (H4) of a BWR core shroud. The H4 weld is a multi-pass submerged-arc weld that joins two type 304 austenitic stainless steel cylinders. An axisymmetric solid element model was used to characterize the detailed evolution of residual stresses in the H4 weld. In the analysis, a series of advanced weld modeling techniques were used to address some specific welding-related issues, such as material melting/re-melting and history annihilation. In addition, a 3-D shell element analysis was performed to quantify specimen removal effects on residual stress measurements based on a sub-structural specimen from a core shroud. The predicted residual stresses in the H4 weld were used as the crack driving force for the subsequent analysis of stress corrosion cracking in the H4 weld. The crack growth behavior was investigated using an advanced finite element alternating method (FEAM). Stress intensity factors were calculated for both axisymmetric circumferential (360°) and circumferential surface cracks. The analysis results obtained from these studies shed light on the residual stress characteristics in core shroud weldments and the effects of residual stresses on stress corrosion cracking behavior.     

X射线衍射法研究刚玉注入层的结构

用Ｘ射线衍射法和ＰＯＷＤ１２理论计算程序探讨了多晶刚玉Ｆｅ离子注入层的结构变化。     

Non-destructive detection and analysis of residual and loading stresses in thick-walled components

Components and systems are designated to withstand loads. These loads are primarily mechanical ones, additionally thermal, chemical and other ones. The constructed part has to support these loads with safety margins. Additionally, peak values for stresses have to be avoided. During the last ten years the theoretical background as well as the numerical evaluation were developed and introduced in practice. Especially finite-element methods at least for loading stresses are the common aid of the designing engineer. The experimental verification of calculated stresses and stress distributions fails up to now. There is no experimental measurement of stress at all. For strain measurements - restricted to elastic strains and to the surface region, not exceeding some ten micrometres - only the X-ray technique allows static and dynamic measurements. Strain variations by changes of loads or stresses can be measured with strain gages, optical holographical interferometry and other methods - also restricted to the surface only. Nothing is known about the volume-distribution of strains and stresses, and for scientists and engineers it is a surprising phenomenon how practicians here rely on theories and calculations. During the last five years several approaches were developed as non-destructive methods for strain/stress-measurements not only on the surface but in the interior, too. The state of the art is described in this contribution covering ultrasonic as well as micromagnetic methods. Examples are given from research results and applications in practice. The most important literature differentiated referring to physics, review contributions and applications is listed in an appendix.     

Determination of thorium in plutonium by X-ray spectrometry

An X-ray fluorescence method for the determination of thorium (0.1 to 1.2 %) in plutonium-238 was developed. The PuO₂ is mounted in a dimpled slide, and the slide is packaged so that the plutonium and thorium L-alpha lines can be counted in a nonradioactive laboratory. A standard deviation of 0.02 % is estimated. The method is applicable to both solid and solution samples.     

Planar irregularities of texture and stress field in Ti detected by X-ray diffraction technique

Regardless of the origin of structure irregularities of materials, the recognition of their spatial distribution in a sample or constructing elements is a great research problem. One of the most effective and non-destructive tools used for this purpose is the X-ray diffraction technique, assisted by an appropriate experimental method and data processing. The work presents the results of investigations of planar distribution of crystallographic texture and stress irregularities manifested by changes of diffraction effects registered by the X-ray technique. As an example, the introduced method is tested on a titanium rod after severe plastic deformation process.     

Evaluation of the 3D residual stress field from X-ray diffraction measurements on weldments of A533 heavy plate

A method for determination of the three-dimensional residual stress distribution in heavy weldments has been developed. The evaluation is based on measured stress data at a number of levels below the plate surface. The method has been applied to two measurements on heavy weldments of A533B steel. The resulting stress fields are in good accordance with other measurements on joints in heavy plate.     

Thermal expansion studies on Inconel-600 by high temperature X-ray diffraction

The lattice thermal expansion characteristics of Inconel-600^® have been studied by high temperature X-ray diffraction (HT-XRD) technique in the temperature range 298-1200 K. Altogether four experimental runs were conducted on thin foils of about 75-100 μm thickness. The diffraction profiles have been accurately calibrated to offset the shift in 2θ values introduced by sample buckling at elevated temperatures. The corrected lattice parameter data have been used to estimate the instantaneous and mean linear thermal expansion coefficients as a function of temperature. The thermal expansion values estimated in the present study show a fair degree of agreement with other existing dilatometer based bulk thermal expansion estimates. The lattice parameter for this alloy at 300 K is found to be 0.3549(1) nm. The mean linear thermal expansivity is found to be 11.4 × 10⁻⁶ K⁻¹.     

微区X射线衍射在矿物鉴定中的应用实例

介绍了微区X射线衍射仪发展的现状,给出了微区X射线衍射仪鉴定物相的研究实例,并讨论了微区X射线衍射法的优、缺点。通过配置有封闭3kWX射线光管、单毛细管透镜、Pixcel探测器和普通CCD视频的Panalytical X’Pert PRO MPDX射线衍射仪,对光片上的铍矿物进行了微区X射线衍射鉴定,结果确定该铍矿物为羟硅铍石。微区X射线衍射法具有微区、微量、原位和无损等优点,能够进行直径在100～300μm范围内的两种或两种以上矿物集合体的物相鉴定。与电子探针等微区手段相互结合、互相补充,鉴定结果更加可靠。     

Monitoring the crystallization process of nano-confined organic molecules by synchrotron X-ray diffraction

The crystallization of two organic molecules, tetrahexil-sexithiophene (H4T6) and dibenzotetrathiafulvalene (DBTTF), into nano-sized cavities has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent evaporation. Thanks to these real time experiments, the phase content has been determined from the onset of the first crystalline molecular assembly to the stable system. The correlation between the size of the nano-cavities and crystallization mechanism, in the complex systems proposed, has been established. The obtained results shows that the nano-confinement can induce organic molecules, for which polymorphs coexistence is otherwise difficult to avoid, to selectively crystallize in a single phase. The proposed system can be applied to a wide range of organic molecules and can be advantageously exploited in different application fields including organic semiconductor devices.     

Introduction of the X-ray diffraction beamline of SSRF

The X-ray diffraction beamline developed at Shanghai Synchrotron Radiation Facility(SSRF)is located at the BL14B1 bending magnet port of the 3.5 Ge V storage ring. The beamline optics is based on a collimating mirror,a sagittally focused double crystal monochromator and a focusing mirror. Photon flux of 4.43 × 1011phs/s at10 ke V is obtained. The primary instrument equipped in the experimental end-station is a Huber 5021 sixcycle diffractometer. BL14B1 is a general purpose X-ray diffraction beamline and focused on material science,condensed matter physics and other relevant fields looking for structural information.     

Numerical simulation of residual stresses induced by laser beam welding in a SUS316 stainless steel pipe with considering initial residual stress influences

With the development of computer hardware and software, numerical simulation technology has been widely used to predict welding temperature field, residual stresses and distortion. However, till now the influences of initial stresses induced by the manufacturing process before welding on the welding-induced residual stresses are rarely investigated experimentally and numerically. In the present work, we have developed a computational approach based on thermal elastic plastic FEM to clarify how the initial stresses due to heat treatment affect the welding-induced residual stresses in an austenitic stainless steel pipe. A heat treatment process, which is similar to solution heat treatment, is employed to produce initial stresses in the pipe before welding. After the heat treatment, the laser beam welding is used to perform a girth weld in the middle of the pipe. Through comparing the residual stress distributions after heat treatment and laser beam welding, we have investigated the influence of the initial residual stresses on the welding-induced residual stresses. The numerical results suggest that the initial residual stresses prior to welding have significant effects on the residual stresses after welding in the pipe model.     

Applications of parametric X-rays for X-ray diffraction analysis

Until now parametric X-rays (PXR) have not had practical applications because of the lack of a modern compact accelerator providing the required beam current and consequently high X-ray photon flux. PXR sources even with the intensities achievable at present may be applied to a number of X-ray reflectometry and diffractometry measurements which are important for the characterization of crystals and multi-layer nanostructures. In the paper we present some proposals for possible PXR applications for a number of X-ray measurements based on the smooth energy tuning, high monochromaticity and directed emission of this radiation. The theoretical background and numerical evaluations for PXR applications for determining ingredient concentration in a solid solution in the range of anomalous dispersion of the defect atoms, determination of the phase structure of a crystal, and selective PXR action in organic compounds, important for medical and biological research, are considered.     

Allowing for the effects of residual stresses on creep in channel tubes

Conclusions The method enables one to calculate the creep strain in reactor structures with allowance for the relaxation of the residual stresses distributed over the wall thickness in the presence of radiation and temperature fields. The result for RBMK channel tubes is that the residual stresses have only a minor effect on the strain in prolonged operation. However, in short-time tests, this factor may appreciably distort the results and may even alter the sign of the strain. The internal stresses may also make themselves felt when one measures the strain due to radiation growth in zirconium-alloy specimens.Translated from Atomnaya Énergiya, Vol. 58, No. 1, pp. 13–17, January, 1985.     

X-ray diffraction study of pure plutonium under pressure

Atomic volume and bulk modulus represent basic cohesion properties of a material and are therefore linked to many other physical properties. However, large discrepancies are found in the literature regarding values for the bulk modulus of pure plutonium (α-phase). New X-ray diffraction measurements of plutonium in diamond anvil cell are presented and the isothermal bulk modulus is extracted.     

电气石的原位高压X射线衍射研究

使用金刚石对顶砧(DAC)高压装置和同步辐射光源,对黑色电气石进行了原位高压X射线衍射研究,实验最高压力达到27.8 GPa.在研究的压力范围内,随着压力的升高,晶胞体积逐步被压缩,晶胞参数a的压缩率小于c.未观察到电气石的结构相变.利用Murnaghan状态方程(K′=4)对电气石的体积-压力数据进行拟合,获得的等热体积模量K298为(183.5±4.2)GPa.     

NSRL衍射和散射线站硬X射线参数测量

描述了NSRL新建X射线衍射和散射光束线站的主要指标测试及其结果,包括X射线单色光斑的CCD成像(4mm×0.5mm)、波长标定和光子通量(0.4×10~9—2.1×10~9 photons·s~(-1)·(100mA)~(-1))的测量;已在该线站上应用同步辐射X射线成功地收集了5组700余幅磷脂酶A2和神经毒蛋白晶体的衍射数据,处理结果良好。