Residual Stress Measurement Methods Research Articles

The Generation, Measurement, Prediction, and Prevention of Residual Stress in Nickel-Based Superalloys: A Review

As a crucial high-performance material, nickel-based superalloys inevitably generate residual stresses during processing, manufacturing, and usage. The mechanical properties of nickel-based superalloys are significantly reduced by residual stress, which becomes one of the important factors restricting material reliability. The systematic analysis of residual stresses in nickel-based superalloys throughout the entire manufacturing and usage processes is insufficient. The residual stress generation factors, measurement methods, prediction models, and control methods in nickel-based superalloys in recent years are summarized in this paper. The current challenge and future development trends in the research process of nickel-based superalloy residual stress are also presented. A theoretical reference for further research on residual stresses in nickel-based superalloys can be provided in this review.

Study of Residual Stress Using Phased Array Ultrasonics in Ti-6AL-4V Wire-Arc Additively Manufactured Components

This paper presents a study on residual stress measurement in wire-arc additively manufactured (WAAM) titanium samples using the non-destructive method of phased array ultrasonics. The contour method (CM) was used for the verification of the phased array ultrasonic results. This allowed for a comparison of measurement methods to understand the effects on the distribution of residual stress (RS) within Ti-6Al-4V samples and the effectiveness of measurement of residual stress using phased array ultrasonics. From the results of the experiments, the phased array ultrasonic data were found to be in good agreement with the CM results and displayed similar residual stress distributions in the samples. The results of the individual elements of the phased array were also compared and an improvement in accuracy was found. From per-element results, anomalies were found and could be mitigated with the ability to average the results by using phased array ultrasonics. Therefore, based on these results, there is a strong case for the benefits of using phased array ultrasonics as a method of residual stress measurement for WAAM Ti-6Al-4V components over other existing residual stress measurement techniques.

Study of Corrsion System on Iron Artefacts through Neutronic Analysis

This study was conducted to confirm the possibility of using the corrosion products of iron artifacts and corrosion systems for non-destructive analysis using neutrons by applying the non-destructive analysis method and the destructive analysis method together to the analysis of the corrosion system of iron artifacts. As a result of transmission analysis, the shape of the artifact, the boundary between the metal layer and the corrosion layer, etc. could be confirmed, and through tomography, the shape, surface shape, and internal cross section of the artifact could be confirmed. It was confirmed that the corrosion thickness using the residual stress measurement method has a high reliability of less than 10% of an error compared to other analysis results, so it is highly likely to be used to measure the corrosion thickness. It was confirmed that the corrosion layer of the iron artifact analyzed this time was mainly Goethite among the types of DPL and was embedded with Magnetite/Maghemite. Since the neutron analysis can estimate the corrosion thickness non-destructive, it is highly likely to be used to study the corrosion rate of iron artifacts by burial environment through additional studies.

Residual Stresses in Alloy IN718 Produced Through Modulated Laser Powder Bed Fusion

BackgroundLaser powder bed fusion (L-PBF) additive manufacturing (AM) is used for building metallic parts layer-by-layer and often generates non-uniform thermal gradients between layers during fabrication, resulting in the development of residual stresses when parts are cooled down.ObjectiveThe impact of modulated laser used during the L-PBF process on residual stresses in Inconel 718 (IN718) material was investigated. The impact of build directions on residual stress is also determined.MethodsThe contour method is employed to measure the full-field residual stress component on the cross-section of samples. A complementary residual stress measurement method, incremental hole drilling, was employed for obtaining in-plane residual stress components.ResultsThe results show that the residual stress distribution is sensitive to the build direction, with a higher magnitude of residual stress in the direction of build than that in the transverse direction. Multiple measurements with the same manufacturing parameters show good repeatability.ConclusionResidual stresses in the as-built parts are significant and hence a further consideration regarding relieving residual stresses is required when post-thermal treatments are developed.

Residual stress analysis in industrial parts: a comprehensive comparison of XRD methods

A recently emerged XRD-based cosα residual stress measurement method, which utilizes imaging plate detectors, has attracted special attention from both academia and industry. There are uncertainties about to which extent the method could be used and about the accuracy of the measurements when analyzing industrial components. This work investigates the accuracy of the method by targeting four common types of material structures for the XRD experiments: preferred orientation of the microstructure (texture effect), coarse grain microstructure (coarse grain effect), a combination of both, and materials with steep lateral or in-depth residual stress gradients. The analysis was carried out by the conventionally used sin2ψ and the newly developed cosα methods on ferritic and austenitic steels, aluminum alloys, and SiSiC ceramics. The results indicate that both methods are reliable in most cases. However, cosα method has higher uncertainties and is more sensitive to the initial microstructure of the material.

Application of Nonlinear Lamb Wave Mixing Method for Residual Stress Measurement in Metal Plate

Harmonic nonlinear ultrasound can offer high sensitivity for residual stress measurements; however, it cannot be used for local stress measurements at a point in space and exhibits nonlinear distortions in the experimental system. This paper presents a feasibility study on the measurement of residual stress in a metal plate using a nonlinear Lamb wave-mixing technique. The resonant conditions for two Lamb waves to generate a mixing frequency wave are obtained via theoretical analysis. Finite element simulations are performed to investigate the nonlinear interactions between the two Lamb waves. Results show that two incident A0 waves interact in regions of material nonlinearity and generate a rightward S0 wave at the sum frequency. Residual stress measurement experiments are conducted on steel plate specimens using the collinear Lamb wave-mixing technique. By setting different delays for two transmitters, the generated sum-frequency component at different spatial locations is measured. Experimental results show that the spatial distribution of the amplitude of the sum-frequency component agrees well with the spatial distribution of the residual stress measured using X-rays. The proposed collinear Lamb wave-mixing method is effective for measuring the distribution of residual stress in metal plates.

Residual Stress Measurement Techniques for Metal Joints, Metallic Coatings and Components in the Railway Industry: A Review

Manufacturing and maintenance procedures in the railway industry regularly implement welding and metal deposition operations to produce joints, coatings and repair structures. During these processes, residual stresses arise through the generation of heat affected zones and plastic deformation. This makes accurate measurements of the internal stresses a critical aspect of manufacturing, monitoring, repair and model validation in the develop new metallic coating and joining technologies. Selection of an appropriate residual stress measurement method has many important factors including component size, resolution and the magnitude and location of internal stresses, often resulting in a combination of techniques required to obtain complete assessment of the stress state. This paper offers a review of residual stress measurement techniques for railway components including rail joints and coatings through comparison of destructive and non-destructive approaches, their measurement capabilities, benefits and limitations. A comprehensive discussion of different applications is provided with a summary of facilities available to both research and industry.

구멍 뚫기 방법을 이용한 균일한 응력장에서의 잔류응력 측정

Residual stress might not only cause structural failure in materials, but also have a significant influence on the safety and life of the object as it superposes with the load applied to machine components or structures. In this paper, the effect of the residual stress analysis procedure and relaxation coefficients was investigated for the practical application of the residual stress measurement method by hole-drilling method, and the reliability of this method was evaluated. To this end, a tensile test was performed to generate a known uniaxial stress field, and the relaxation strain was measured by drilling, and the residual stress was analyzed and compared. Under the conditions of the tensile test, the given longitudinal stress was 49.0 MPa and the transverse stress was 0, while the measured principal stresses were 40.0 MPa and -2.72 MPa. Considering that the general residual stress measurement method has an error of about 20-50%, it is shown that the residual stress measurement results obtained in this paper are reliable.

Interlaboratory Reproducibility of Contour Method Data in a High Strength Aluminum Alloy

BackgroundThe contour method for residual stress measurement has seen significant development, but an experimental reproducibility study utilizing physical samples has not been published.ObjectiveA double-blind reproducibly study is reported, having scope beginning with EDM cutting and ending with residual stress calculation.MethodsA reinforced I-beam sample geometry is identified for its unique residual stress profile when extracted from residual stress bearing quenched aluminum bar (7050-T74). Contour measurements are prescribed on a midplane of symmetry with dimensions 24.0 mm by 50.0 mm. Fourteen identically prepared samples are fabricated from a single long bar with well characterized and uniform residual stress. Five samples throughout the bar are identified for planning measurements to validate sample uniformity and overall suitability of the residual stress field. The planning measurements employ a range of techniques: contour method, neutron diffraction, and hole-drilling. Eight samples are distributed to an international group of participants to execute their standard measurement practice. A double-blind process is followed to provide anonymity.ResultsResults are provided by eight participants: six being self-similar and two being quite different, the latter set aside as outliers. An average residual stress field is established from non-outlying results and the spatial distribution of reproducibility standard deviation is determined. The average stress field ranges from -60 to 70 MPa and the reproducibility standard deviation averages 8.1 MPa on the measurement plane. The average reproducibility standard deviation is about 3 × larger for points within 1.0 mm of plane boundaries (17.6 MPa) than for the remaining points (6.1 MPa).ConclusionsReproducibility standard deviation (among different labs) for contour method residual stress measurement is found to be very similar to repeatability standard deviation (in a single lab) reported in prior work. The reproducibility observed here, for the entire measurement process, is also similar to that found in a prior reproducibility study limited to contour method data analysis.

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.

Comparison of Non-Destructive Residual Stress Measurement Methods for Additive Manufactured Alsi10mg Alloys

Comparison of Non-Destructive Residual Stress Measurement Methods for Additive Manufactured Alsi10mg Alloys

Identifying the causes of residual stress in polycrystalline diamond compact (PDC) cutters by X-Ray diffraction technique

An attempt was made to identify the sources of residual stress in polycrystalline diamond compact (PDC) cutters by X-ray diffraction (XRD) technique. PDC retains residual stress after sintering and this residual stress plays an important role for cutter performance. X-ray diffraction method of residual stress measurement is very common because it is nondestructive. Residual stress was measured in a finished 16 mm PDC cutter and changes in residual stress were observed as the substrate was removed by grinding. Residual stress was also measured after full removal of cobalt from the diamond table by leaching. Comparison was made between the as-pressed PDC cutter, after removing the substrate, and after removing the cobalt to understand the relative contribution of geometry and cobalt binder to overall residual stress. An additional measurement was made under High Pressure High Temperature (HPHT) compacted diamond powder in the absence of cobalt to evaluate the contribution of high temperature deformation of diamond particle on residual stress.

Comparison of Residual Stress Measurement Methods in Solid Oxide Fuel Cell

SOFCs need to be able to operate for long periods of time without significant degradation in performance, and mechanical reliability and durability are problems that need to be addressed.Since SOFC operate at high temperatures and in oxidizing and reducing atmospheres, it is difficult to measure residual stress in-situ under actual operating conditions. Therefore, evaluation methods during operation have not been fully developed. Current methods for measuring residual stress in SOFC include curvature method, X-ray stress measurement method, and Raman scattering spectroscopy.In the curvature method, the stress is obtained by combining curvature, anode substrate thickness, and elastic modulus. Therefore, it is not suitable for residual stress measurement during reduction and re-oxidation of anodes, where physical properties such as elastic modulus change with time.In the X-ray stress measurement method, the change in lattice strain is measured, and the stress is obtained by multiplying the strain by an elastic constant. Typical methods of X-ray stress measurement are sin2ψ method and cosα method. The characteristics of the sin2ψ method are as follows;(1)By using several measuring points to determine the stress value, the variation of the measured value can be suppressed, resulting in high measurement accuracy. Furthermore, the reliability limit of the measured value can be quickly evaluated from the linearity.(2)A goniometer mechanism is used to measure the diffraction profile, which requires a large device.(3)Measurement time is long because several points are measured by moving the angle of incidence.Thus, although the sin2ψ method has high measurement accuracy, it is not very suitable for in-situ measurements.The method devised to solve these problems is cosα method. The characteristics of the cosα method are as follows;(1) Since it is single-incidence, the optical system is simple and does not require goniometric scanning, making it possible to reduce the size and weight of the measurement system. It is also possible to measure in a short time.(2) From the slope of the cosα and sinα diagrams, vertical stress and shear stress can be measured simultaneously. In addition, the reliability of the stress values can be evaluated from the linearity of the diagram.(3) In the case of coarse grains or strongly aggregated structure, only continuous rings can be obtained, or the strength may be significantly non-uniform, making stress measurement difficult.It has been demonstrated that the measurement accuracy of the cosα method for vertical stress is comparable to that of the sin2ψ method, and moreover, it is suitable for in-situ residual stress measurement because of its rapidity and simplicity.In Raman scattering spectroscopy, the change in lattice volume, i.e., the change in stress conditions, can be obtained by measuring the Raman shift. The characteristics of the Raman scattering spectroscopy are as follows;(1) Since the measurement can be performed under atmospheric pressure and through glass, it is suitable for in-situ measurement in the SOFC operating environment where atmosphere control is usual.(2)High spatial resolution (up to ~1µm resolution is possible with micro-Raman spectrometers) enables measurement of small areas.(3) Since Raman peaks with sufficiently strong intensity need to appear in the Raman spectrum, there is a limit to the number of materials that can be measured. Among the SOFC constituent materials, ceria-based materials are the most suitable for observation.As mentioned in (3), Raman scattering spectroscopy is used to calculate the stress value of the interlayer (ceria-based material). Therefore, the stress in the electrolyte is calculated by assuming that the electrolyte and the interlayer are rigid bodies under the operating conditions. In this study, we performed in-situ measurement of residual stress in the anode-supported cell using sin2ψ method, cosα method and Raman scattering spectroscopy. And then we compared the results and summarized the advantages and disadvantages of each method. We used a commercially available general cell and a cell fabricated at Tsinghua University. In order to reproduce the actual operating conditions, the measurements were carried out under elevated temperature and under reduced temperature. Since the anode may be re-oxidized when the fuel runs out or during an emergency shutdown, the measurements were also conducted under re-oxidation. Furthermore, we proposed suitable conditions for each measurement method and conducted experiments under those conditions.

Comparison of Residual Stress Measurement Methods in Solid Oxide Fuel Cell

We performed in-situ measurement of residual stress in an anode-supported cell using sin2 ψ method, cosα method, and Raman scattering spectroscopy. Residual stress at room temperature was evaluated by the sin2 ψ method, cosα method, and simulation. The stress values were generally consistent among the methods, with YSZ having a compressive stress of around 600 MPa. Residual stress analysis at high temperatures was attempted using Raman scattering spectroscopy which, however, was difficult to be applied above 700˚C. Instead, cosα method was successfully utilized for the measurement of residual stress during the temperature rise, reduction, and re-oxidation processes. The stress on the electrolyte observed during reduction and re-oxidation was different from that expected with a simple assumption of layered homogeneous sheets. These results showed that the cosα method is the most suitable method for in-situ measurements to validate simulated stress states.

Noise-insensitive contour method for residual stress measurement in laser butt welding

The residual stress distribution of laser welding greatly affects the overall mechanical response of the welded structure. In this study, a new residual stress measurement method is proposed, using the finite element method (FEM) to optimize and modify the contour method. The distribution of the welding residual stress is simulated via B-spline interpolation and by solving an unconstrained weighted least-square problem in parallel, using the Levenberg–Marquardt algorithm. The control points of the B-spline are obtained to determine the residual stress distribution. For numerical verification, the residual stress dataset is generated by simulating the laser welding process, and the calculation efficiency of the FE-modified contour method is tested on this prior dataset. It is verified that the proposed method does not depend on the initial value of the residual stress distribution. This residual stress measurement method is an improvement over the traditional contour method and can achieve satisfactory accuracy, even under the influence of Gaussian noise and signal-to-noise ratio noise. In the experiments, the contour data of the laser welding seam cutting surface are obtained by employing electrical discharge cutting and three-dimensional displacement scanning technology. The traditional and FE-modified contour methods are used to identify the residual stress in the welding direction. The results show that the proposed method can adapt to contour measurement data under actual complex working conditions.

A Method to Combine Residual Stress Measurements from XRD and IHD using Series Expansion

It is common practice to use various residual stress measurement methods to complement each other and fully define a through-thickness stress distribution. Incremental hole-drilling (IHD) and X-ray diffraction (XRD) are two of the most widely used techniques. Although IHD readily provides stress data to some depth, the method is susceptible to large stress uncertainties near the surface. XRD, in contrast, is most suited to finding near-surface stresses. Constrain the residual stress distributions obtained through series expansion by using XRD measurements, thereby obtaining full depth stress measurements with reduced uncertainty near the surface. The proposed method enforces suitable relationships between the amplitude coefficients of the series expansion such that the resultant stress distributions match the XRD measurements. The method is demonstrated on an aluminium alloy 7075 specimen of 10 mm thickness that underwent laser shock peening treatment. Strong correlation in calculated residual stress distributions was found between the proposed method, standard series expansion and the regularized integral method. The proposed method has reduced stress uncertainty near the surface when compared to both standard series expansion and integral methods of IHD due to its incorporation of near-surface XRD data. The proposed method allows XRD measurements to be rigorously incorporated into IHD results. The effect of XRD uncertainty on the overall IHD stress distribution is localised to the near-surface measurements.

Konturni metod u određivanju aksijalnih rezidualnih napona kod hladno ekstrudiranih čeličnih šipki

Residual stresses in cold extruded parts play an important role in both component lifetime and succeeding in manufacturing performance. When a cold extruded part is used directly, the lifetime of the part depends on the residual stresses induced during cold extrusion. On the other hand, if the part is exposed to post operations such as machining, residual stresses may cause distortions. Despite their importance, there are only a few residual stress measurement methods to assess axial residual stresses in full cylindrical thick components of massive forming. As high-energy X-ray and neutron diffraction methods are less available and considerably expensive, the contour method may be an alternative providing the accurate assessment of residual stresses without requiring specialized facilities. In the present work, residual stresses in cold extruded rods are determined via the contour method for various extrusion ratios. The finite element analyses for the same conditions are also carried out to provide the comparison to the contour method. The results indicate that the contour method can be a valuable candidate for the measurement of axial residual stresses in cold extruded thick components.

Evaluation methods for residual stress measurement in large components

Residual stresses play a pivotal role in determining the durability and service life of the component. Processes such as heating, machining, mechanical treatment and even the manufacturing process itself, develop the residual stresses in a component. These initial residual stresses rejig themselves depending on different loading conditions such as rotation, mechanical or thermal loadings. Furthermore, having categorical knowledge about the residual stress field across the whole component is imperative in comprehending how residual stresses impact failure. So, it is vital to determine the stress distribution throughout the component to mitigate the catastrophic failure. This is easy to obtain in case of smaller components due to their small cross-sections, but the same becomes daunting when it comes to large components because of greater depths at which these stresses reside and also of their large cross-sections. Though there are several techniques to measure the residual stresses in large components but work only up to certain depths which restricts there use to specific part dimensions which in turn necessitate to decide the best method for determining the complete stress distribution in large components. Thus, this review aims to elucidate and classify various residual stress measurement methods on the basis of their operating range, principle and technical feasibility with manufacturing process used to manufacture the large engineering components.

The incremental contour method using asymmetric stiffness cuts

An incremental Contour Method (iCM) of residual stress measurement is proposed where residual stresses in the body of interest are sequentially reduced by successive contour cuts and the risk of stress re-distribution plasticity is mitigated or eliminated. The cutting-induced plasticity is known to cause significant inaccuracies when trying to measure the near-yield residual stresses using a conventional single cut contour method. The iCM procedure implements a new displacement data processing approach for the general case of sectioning at an arbitrary plane where the cut parts do not possess mirror-symmetric elastic stiffness. The basis for the new asymmetric stiffness data analysis approach is presented and the accuracy of the new method demonstrated using both numerical and experimental case studies.

Advances in analysis of total uncertainties in a semi‐invasive residual stress measurement method

AbstractThe ability to characterise residual stress distribution accurately and over different length scales, particularly deep into an engineering part, plays a significant role in assessing structural integrity. Two most commonly used techniques to measure residual stress fields deep into engineering components include neutron diffraction (ND) and deep‐hole drilling (DHD). As the measurements depend on several physical quantities, they are susceptible to error. The error or uncertainties may turn substantial and compromise the suitability of the results. Although noninvasive, the neutron diffraction technique is neither readily available nor portable and is limited to approximately 60‐mm‐thick specimen; errors associated with results become unacceptable at greater flight paths. Moreover, a mock‐up representing the engineering component is normally used in the ND technique. In contrast, the DHD technique is portable and measures residual stresses with high spatial resolution. An error propagation technique was applied to develop an error analysis procedure taking into consideration various stages of the DHD method and successfully applied to different DHD measurements. An essential feature comprising the effect of plasticity due to the creation of reference hole in the DHD procedure has not yet been taken into account in the error analysis procedure. This paper briefly describes how the uncertainties due to the creation of the initial reference hole can be determined. The effect of plasticity in the drilling procedure is quantified in this study. This error is combined with other sources of error and formulated to determine the total error. An incremental DHD technique was used to measure the complex triaxial residual stress field in an as‐welded circular disc, and the measured data were used to illustrate the total error using the error analysis method developed in the study.