X-ray Residual Stress Measurements Research Articles

Ambient formation of high pressure Ag2Si2O5 and non-stoichiometric Ag0.3Al0.7 alloy under confinement

We report results of Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Analysis of X-rays (EDAX), X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectivity (XRR), and X-ray Diffraction (XRD) and residual stress measurement studies of Ag-silica composite films on Al(001) co-deposited from precursors and spin-coated at different frequencies under ambient conditions. FESEM and EDAX show Ag nanoparticle formation, and XRD, XPS, and XRR show Ag0.3Al0.7 alloy and Ag-rich silicate Ag2Si2O5 formation in all samples. The alloy is non-stoichiometric and non-equilibrium, while the silicate forms at high oxygen pressure. XRR shows the presence of three layers, nanoparticles on top, silicate in the middle, and alloy at the bottom, on an Ag-doped Al substrate. Film thickness decreases exponentially with frequency. Individual layers increase in crystal domain size with a frequency of 3000 rpm when the silicate layer thins below unit cell thickness and the growth has a two-dimensional preference. Our results suggest total confinement by film thinning and local confinement from the Ag nanolayer. Residual stress measurements on the films deposited at 500 and 5000 rpms show a gradual increase in the tensile stress. The increase in spinning frequency reveals the formation of high pressure ambience.

Residual stress and microstructure control in welding of SA508 low alloy steel

Various types of solid-state phase transformation (SSPT) occur during the SA508 steel welding process, especially for multi-pass welding. The multiple thermal cycles lead to a more complex microstructure distribution and significantly influence the residual stress distribution. Therefore, to better control the microstructure and residual stress, it is necessary to optimize the process parameters which are closely related to the welding thermal cycles. This study established a thermo-mechanical-metallurgical multi-field coupling model and then validated it using X-ray and neutron diffraction residual stress measurement tests. Furthermore, the influence of welding heat input and preheating temperature on the formation of phase constituents and the ultimate residual stress field were analyzed in detail, concomitantly with a comprehensive discussion on their underlying mechanisms. The results showed that the increase of heat input expanded the domain occupied by the bainite phase, accompanied by the increase of compressive stress region. Moreover, the rise of preheating temperature promoted the bainite phase transformation, thus decreasing the longitudinal compressive stress and the stress gradient. The variation induced by welding parameters was closely related to the welding cooling rates. To obtain a full bainite and low residual stress condition of welded joint, it becomes imperative to exercise control over cooling rates, maintaining them at approximately 1.0 °C/s.

Finite element simulation on residual stress during immersion quenching and pre-stretching of Al7055 thick plates

During the immersion quenching process, severe temperature changes and significant temperature differences between the core and superficial area can give rise to high residual stresses within the aluminum alloy thick plate to cause subsequent machining distortion of the thin-walled part. Reducing the residual stress within the thick plate can effectively minimize the distortion in part. In this research, ABAQUS software was adopted to simulate the internal temperature and stress fields of thick plates of Al7055 alloy during the quenching and pre-stretching processes, sequentially and respectively. In addition, the x-ray residual stress measurement method was used to measure and characterize the surface residual stress of the plates. The results indicate that the medium temperature affects residual stress inside the thick plate significantly during the immersion quenching process. The level of which inside the plate gradually increases as the medium temperature decreases. Further, the pre-stretching treatment can effectively reduce residual stresses within the thick plate, and the residual stress level gradually decreases with the pre-stretching ratio increasing. The experimental results verify the feasibility of numerical simulation to predict the status of quenching stress in thick plates. Subsequently, a simulation study for material removal processes was carried out based on the above studies. The results reveal that the thin-walled part’s machining distortion degree improves as the raw thick plate’s initial quench residual stress level decreases.

Finite Element and Experimental Analysis of Residual Stresses in Electron Beam Welded Nickel-Based Superalloys

In this paper, two different nickel-based superalloys, namely Inconel 718 and Nimonic 80A were joined using electron beam welding techniques with three different welding parameters. A finite element analysis (FEA) using Abaqus software was carried out to calculate the residual stresses due to welding. Both transverse and longitudinal residual stresses were determined. Also, an X-ray residual stress measurement system, μ-X360 Ver. 2.5.6.2 was used for measuring transverse residual stress along and across the weld centerline. The transverse residual stress found by FEA and that measured experimentally was nearly the same thus validating the FEA. Also, the peak values of longitudinal residual stress found using the FEA were close to the yield strengths of the base metals as found elsewhere.

Stress Engineering as a Strategy to Achieve High Ferroelectricity in Thick Hafnia Using Interlayer

Binary oxides of Hf0.5Zr0.5O2 (HZO) have attracted considerable attention of the ferroelectric research community, owing to their excellent ferroelectric properties and CMOS compatibility. In particular, HZO films of a relatively high thickness (>10 nm) are studied widely for sensor and display applications. However, one of the major constraints of HZO materials is the formation of monoclinic phases (m-phase) with increasing film thickness resulting in the degradation of its remanent polarization ( ${P}_{r}$ ). Herein, we present a stress engineering method to achieve high ferroelectricity in thick hafnia using an interlayer. In our work, we attempted to address the aforesaid limitation of HZO by inserting a dielectric interlayer and elucidated the influence of interlayer on the relatively thick HZO films. high resolution TEM (HRTEM) analysis revealed that the presence of interlayer allows the growth of the top and bottom HZO layer in an independent direction thereby preventing the loss of ferroelectricity in HZO films with higher thickness by controlling its grain size. Similarly, grain angle incidence X-ray diffraction (GIXRD) and residual stress measurements suggest that the interlayer affects the o-phase formation from the t-phase owing to the tensile stress applied to the HZO films because of the coefficient of thermal expansion (CTE) mismatch between the HZO and interlayer. In our study, an improved $2{P}_{r}$ value of 30.2 $\mu \text{C}$ /cm2 was achieved by inserting a TiO2 dielectric interlayer in a relatively thicker HZO film. We believe that this approach can be adopted in various applications such as sensors, displays, and memory devices.

Experimental investigations of effect of tempering on residual stresses developed during the turning operation

The Cos α method has emerges as new technique for measurement of the residual stresses using whole Debye-Scherrer ring recorded on two dimensional imaging plates (IPs) with the help of X-ray residual stress measurement system μ-X360 Ver. 2. 3. 0. 1. Considering with more accountability of the tempering treatment process for decreasing or eliminating the residual stresses, the effect of tempering is monitored experimentally. The main objectives of this paper is to predict the residual stresses distribution, and surface roughness of the machined samples (with and without tempered) on CNC lathe at the same process parameters (speed, feed and depth of cut) using tungsten carbide tool. Surface residual stresses of five turned specimen with and without tempered have been measured. The residual stress graphs, FWHM (full width at half maximum) graphs and Debye –scherrer rings, and surface roughness of all samples have been obtained and critically studied. The residual stress and surface roughness were found minimum in sample tempered at 450°C. The min and max peak values were found as 149 k and 175 k for samples tempered at 450°C and untempered respectively. The average surface roughness (Ra = 2.06, Rq = 10.4 and Rz = 2.45) and(Ra = 3.65,Rq = 16.9 and Rz = 4.27) were seen in sample tempered at 450°C and untempered respectively. The results obtained from the present experiment, literature review and the theoretical study validate the present work and method in strong confirmation and bear a good agreement among them.

Microstructural, Dynamic and Residual Stress Analysis of Metal Matrix Composite Shafts

Metal matrix shafts are widely used in industries, and various research works are available for the characterization and applications of these components. These research works are limited to the conventional characterization of the material. In this paper, a novel characterization approach has been adopted, which determines the effect of reinforcements on the dynamic properties and residual stress of the Al 6061/Al2O3 shafts. Long and slender shafts were fabricated through a stir casting process. Grain structure was obtained through optical microscopy, and morphological evaluation of the composites was performed through scanning electron microscopy. In addition, X-ray diffraction patterns were analysed, and residual stress was calculated by X-ray residual stress measurement system μ-X360 Ver. 2.3.0.1. Tensile residual stress was observed for pure Al 6061 alloy shaft on the surface of shafts, whereas compressive residual stress was observed in the case of composite shafts. The magnitude of the compressive residual stress increased with the increased wt% of alumina in the Al 6061 matrix. The amplitudes of vibration were also reduced by the introduction of reinforcements in metal matrix composites.

Relationship Between Forced Vibration Method and Residual Stress in Die Materials

During aluminum die-casting, tensile residual stress accumulates on the cavity surface of the die by repeated heating and cooling processes. Recently, to improve productivity, dies with high cycle and longer life have become necessary, and reduction or removal of tensile residual stress can be used to prevent heat cracks that cause mold fracture. Heat treatment is often used for residual stress reduction but a more efficient residual stress reduction method that can be carried out with simpler equipment is required. In this study, the relationship between the residual stress after forced vibration and the amplitude at the time of excitation is investigated by mechanical vibration of the SKD61 die materials and the die-casting mold through the application of forced vibration by an eccentric motor. Residual stress on the surface of each test plate treated by the heat treatment and the surface of mold cavity after excitation is evaluated by the X-ray residual stress measurement. It was found that the residual strain after excitation accumulated in compression as the amplitude of oscillation of the specimen became negative. Residual stress in the excitation direction of the specimens increased in the compression direction due to the excitation, demonstrating the effective stress reduction by the excitation method.

X-ray metal material evaluation using an SOI pixel detector

The technology for evaluation of metal materials encompasses machine parts and structures. Residual stress is one indicator used for evaluating the strength and stiffness of metal materials. X-ray residual stress measurement is a non-destructive, non-contact, and precise method in various residual stress measurement methods. This method is used only for research purposes because of its long measurement time and large device size. Therefore, we developed a small, high-speed X-ray residual stress measurement device with a charge-integration-type silicon-on-insulator (SOI) pixel detector, INTPIX4, for industrial use.Previous studies have shown that residual stress can be measured in less than 1 s by using a measurement device with an SOI pixel detector. In this study, we report a more detailed specification of the measurement device and consider its availability for metal material evaluation.

Development of integration-type silicon-on-insulator monolithic pixel detectors using a float zone silicon

In this paper, we describe the development of monolithic pixel detectors using silicon-on-insulator (SOI) technology for a rapid X-ray residual stress measurement system. Conventional two-dimensional X-ray detectors are not suitable for rapid X-ray residual stress measurement because of their large pixel size and slow readout. For this reason, we developed highly sensitive SOI monolithic pixel detectors that are made up of smaller pixels and can provide a more rapid X-ray residual stress measurement readout. The detectors are fabricated using a 0.2μm CMOS fully-depleted SOI process (Lapis Semiconductor Co., Ltd). The SOI wafer is made by directly bonding a thick, high-resistivity Si wafer and a low-resistivity Si CMOS wafer. The process does not make use of mechanical bump bonding. We developed an integration-type SOI pixel detector, INTPIX4, for a rapid X-ray residual stress measurement system; it uses a float zone (FZ) or Czochralski (Cz) silicon wafer. Cz SOI detectors have been in use since 2005. After 2011, FZ SOI detectors were successfully fabricated. In this paper, we state recent progresses and test results of the SOI monolithic pixel detector using a FZ silicon and compare them with the results obtained using the Cz detector.

溶接施工条件に着目した抵抗スポット溶接継手表面における X 線残留応力測定手法の適用に関する検討

溶接施工条件に着目した抵抗スポット溶接継手表面における X 線残留応力測定手法の適用に関する検討

An energy-based nanoindentation method to assess localized residual stresses and mechanical properties on shot-peened materials

Abstract

Analytical and Numerical Crack Growth Analysis of 1:3 Scaled Railway Axle Specimens

This paper deals with experimental fatigue crack propagation in rotating bending loaded round bar specimens as well as an analytical and numerical analysis of the residual lifetime. Constant amplitude (CA) load tests are performed with the surface crack length being evaluated using an optical measurement system. Fracture surfaces are microscopically analyzed to determine crack growth in depth as well as the crack shape. In spite of identical testing conditions, the experimental results show some scatter in residual lifetime, which is mainly caused by different residual stress states. Although X-ray residual stress measurements reveal only minor values, a superposition of the residual stress state with the load-induced stress leads to a significant impact on the residual lifetime calculations, which explains the experimental scatter. Numerical analyses are conducted to consider the residual stress state and their effect on crack propagation by different options. Considering the residual stress distribution in depth within the residual lifetime assessment, the deviation to the most conservative experiment is reduced from +48% to +2%. In conclusion, the results in this paper highlight that it is of utmost importance to consider local residual stress conditions in the course of a crack propagation analysis in order to properly assess the residual lifetime.

The cos<i>α</i> method for X-ray residual stress measurement using two-dimensional detector

X-ray stress measurement is widely used as one of the most powerful nondestructive tools to measure residual stresses in polycrystalline solids. In most cases, the sin2Ψ method has been used to determine the stress. In recent years, however, the cosα method has attracted engineers as a new method to measure the stress using two-dimensional detectors, such as imaging plates. The present article is the review of the state of the art of the cosα method. For biaxial stress cases, the cosα method utilizes the whole Debye-Scherrer ring recorded on a two-dimensional detector taken by single exposure of X-rays, and normal and shear stresses are determined simultaneously. The accuracy of the stress measurement of the cosα method has been confirmed to be equivalent to that of the sin2Ψ method for various metals. The simple optical system of the cosα method makes stress analyzers smaller, lighter and more convenient to use for on-site or field measurements. A recent portable stress analyzer adopting the cosα method shortens the measurement time to 60 s. The method has been further developed to analyze triaxial residual stresses. Various advantages of the cosα method are highlighted in comparison with the other methods of X-ray stress determination. Applications of the cosα method to machines and engineering structures are presented, together with future perspectives of the method.

FE analysis of shot-peening-induced residual stresses of AISI 304 stainless steel by considering mesh density and friction coefficient

ABSTRACT In order to investigate the effect of shot peening (SP) on residual stress distribution of AISI 304 stainless steel, a 3D dynamic model for describing single and multiple shot impact phenomenon was built via ABAQUS/Explicit 6.10 by considering the mesh density of treated component as well as the friction coefficient between shot and treated component and validated via X-ray residual stress measurement. The results show that an optimal surface element size about 1/18th of the dimple diameter and reasonable friction coefficient of μ > 0.2 are the key factors for the accuracy of residual stress estimation and the computational efficiency. The error of simulated residual stresses indicates the effect of the deformation-induced martensitic transformation phenomenon should be considered in AISI 304 stainless steel SP model. The effects of shot hardness, impact angle, velocity, diameter and coverage ratio on residual stress distribution were examined and discussed via the optimised SP model.

Fatigue strength of welded and high frequency mechanical impact (HFMI) post-treated steel joints under constant and variable amplitude loading

This study presents fatigue test results of longitudinal stiffener specimens in as-welded and high frequency mechanical impact (HFMI) post-treated condition under both constant amplitude loading (CAL) and variable amplitude loading (VAL). The experiments incorporate mild steel S355 and high-strength steel S700 samples at load stress ratios of R = 0.1 and R = −1 respectively. VAL tests are performed utilizing a straight-line distribution with a sequence length of 2 ⋅ 105 load-cycles and an omission level of 19% of the maximum stress range. The test results reveal a significant benefit of the HFMI-treatment under CAL. On the contrary, the increase in fatigue strength is majorly reduced in case of VAL. X-ray residual stress measurements for the investigated mild steel S355 specimens demonstrate that even at comparably minor load stress ranges, a certain relaxation of the HFMI-treatment induced local compressive residual stress state at the weld toe occurs. This phenomenon contributes to the decrease of the benefit by the HFMI-treatment under VAL compared to CAL. An evaluation of specified damage sums on the basis of the determination of an equivalent stress range for VAL reveals that damage sums between D = 1.0 and D = 0.5 are well applicable for a conservative fatigue assessment on the basis of the IIW-recommended fatigue design curves. However, facilitating a lightweight component design by considering experimental test results of HFMI-treated joints under CAL, a reduced specified damage sum of D = 0.3, or even of D = 0.2 in case of fluctuating mean stress states, is suggested for the fatigue assessment to avoid non-conservative results.

Stability of high frequency mechanical impact (HFMI) post-treatment induced residual stress states under cyclic loading of welded steel joints

This paper investigates the effect of cyclic loading on the stability of compressive residual stress fields induced by high frequency mechanical impact (HFMI) post-weld treatment. First, the effectiveness of the post-treatment technique is shown by fatigue tests incorporating mild steel S355 and high-strength steel S960 longitudinal stiffener specimens. Extensive X-ray residual stress measurements support the beneficial impact on the compressive residual stress state for mild and high-strength steel structures. They also illustrate that cyclic loading leads to a significant local relaxation of this condition. Second, a numerical simulation chain incorporating a structural weld simulation, numerical analysis of the HFMI-treatment, and a final cyclic loading step for the investigated mild steel specimen is set-up. The results show that the residual stresses at the surface of the weld toe are in agreement to the X-ray measurements for both the as-welded and HFMI-treated condition, which basically proofs the applicability of the manufacturing simulation. The numerical computation including the first five load-cycles demonstrates that the simulated residual stress relaxation again exhibits consistent results with the measurements. An additional utilization of an analytical relaxation model from literature reveals that the estimation of the residual stress state in the high-cycle fatigue region is well employable. Therefore, the scientific results in this paper proof the applicability of the presented consecutive numerical-analytical procedure to assess the local compressive residual stress stability of HFMI-treated welded steel joints in both the low- and high-cycle fatigue region.

Cos <i>α</i> 法による円筒面のX線応力測定

The investigation was made on the phenomena observed in the X-ray stress measurement on a curved surface by the cos α method. Numerical analysis was performed simulating the cos α method for the circumferential stress and the axial stress on a cylindrical surface. The X-ray residual stress measurements by the cos α method and the sin2ψ method were carried out respectively for the blasted surface of round steel bars with various diameters. It was found that the debye ring turned oval and the slope of cos α diagram decreased as the ratio of the X-ray beam size to the bar diameter increased, i.e. the magnitude of the measured stress was smaller than that of actual one. These tendencies were remarkable in the circumferential stress measurement. With respect to the relation between the X-ray beam size and the measured value of stress, the difference between the cos α method and the sin2ψ method was found to be small. The measurement error due to a cylindrical surface was negligible when the X-ray beam size was less than 1/3 of the diameter.

X-Ray Residual Stress Measurement of Austenitic Stainless Steel Based on Fourier Analysis

In a previous study, the authors introduced a new nondestructive method to measure stress with a two-dimensional X-ray diffraction image. This method was tested on a carbon steel specimen. To apply this method to the structures of nuclear power plants, it is essential to show that the residual stress of austenitic stainless steel can be measured. We report on an experiment in which the method was used to measure the stress in austenitic stainless steel standards. The results were consistent with the specification of the stress standard and the conventional sin2 ψ method. We conclude that the proposed method is promising for residual stress measurement of austenitic stainless steels.

X線残留応力測定による古貨銭の偽造に関する調査

X線残留応力測定による古貨銭の偽造に関する調査