Residual Stress Measurements Research Articles

Production and Forming of Deposition‐Welded Hybrid Multimaterial Shafts

The combination of several materials in one component can contribute to increased performance. Herein, three types of hybrid components are manufactured using two cladding processes and one joining process. The resulting workpieces are then formed and tested to determine the potential of the different material combinations. Two types of workpieces are produced to investigate multilayer claddings made of different materials, which serve to positively adjust the residual stress. The workpieces are tested using microstructural images and hardness measurements to characterize the microstructure and properties of the intermediate layers. In addition, residual stress measurements are carried out to determine the residual stress ratios. Compressive residual stresses are present in the subsurface of the welded and subsequently formed layer, which will improve the service life in case of rolling load conditions. The third type of workpiece is a combination of aluminum alloy and steel with a cladding layer that combines the performance of the cladding material in the bearing seat with the weight reduction of the aluminum alloy. Scanning Electron Microscopy (SEM) measurements are used to determine whether the application of the cladding has an influence on the intermetallic phase seam in the joining zone of aluminum alloy and steel.

Non-destructive ultrasonic measurement of residual stress in metallic materials

<p>The relationship between the applied stress σ, and the measured shear wave birefringence <b>B</b> was measured in the laboratory for several low alloy steel. The birefringence response was measured with a dual polarization electromagnetic transducer comparing the time of flight for the two polarizations, in the rolling direction and the transverse direction. This stress-birefringence relationship showed a linear dependence and can be described with the relation σ = <b>K</b> * <b>B</b> + σ<sub>0</sub>. The slope of this relationship when applying a tensile stress in the transverse direction of the sample, <b>K</b>, was measured to − 1280 MPa/<b>B</b>(%) and was independent of material chemistry, whereas the position/offset of the curves, i.e., σ<sub>0</sub> , varied in between steel grades, assumed to be due to microstructural texture. A non-contact EMAT probe has been installed in a levelling mill at SSAB Special Steel in Oxelösund, Sweden, to measure the residual stress dependence on the levelling process, in daily production of steel plates. The EMAT probe has been provided by Nordinkraft AG, Remchingen, Germany. This single EMAT probe has been applied along the centerline of plates. Measurements have been made on more than 2000 plates. The responsive or reactive residual stress was successfully measured and calculated for all plates using the above stress-birefringence relationship, showing typical residual stress difference values on the production plates after levelling in the range of less than ± 100 MPa.

Ultrasonic and conventional fatigue behavior, strain rate sensitivity, and structural design methods for wrought and cold spray Al-6061

Cold spray is an additive manufacturing process that accelerates powder particles to supersonic speeds to create repairs and bulk depositions with fine-grained microstructures, high density, and good mechanical properties. Fatigue property measurement for these novel materials is critical for their use in safety-critical components, which can be accelerated with the use of ultrasonic fatigue testing. In this work, ultrasonic (20 kHz) and conventional (20 Hz) fatigue studies were conducted on as-sprayed bulk Al-6061 and conventional wrought Al-6061-T6. Complementary fatigue studies of surface preparation (surface finish and residual stress) and fatigue specimen geometry (round versus flat), as well as hole-drilling residual stress measurements, were undertaken to minimize the influence of these confounding variables. Cold spray Al-6061 exhibits fatigue frequency sensitivity, whereas the wrought material does not. Tensile testing at varied strain rates indicates that a portion of the fatigue frequency effect can be attributed to strain rate sensitivity. Fractographic studies show that crack initiation occurs from unbonded powder particles at the surface at high stress amplitude, and transitions sub-surface at lower stress amplitude. The results of these studies were used to create frequency-corrective models of S-N data and Kitagawa-Takahashi diagrams that can be used to design for fatigue crack initiation and growth resistance.

Durability of cellulose nanofibril films examined via residual drying stress measurement

Durability of cellulose nanofibril films examined via residual drying stress measurement

A comparative study of residual stress measurement of laminated composites using FBG sensor, DIC technique, and strain gauge

A comparative study of residual stress measurement of laminated composites using FBG sensor, DIC technique, and strain gauge

Diminishing residual stress and distortion by in-situ rolling tensioning to increase fatigue performance of friction stir welded AA2024-T3 joints

In this research, local mechanical tensioning treatment in the form of in-situ rolling tensioning (ISRT) was applied during friction stir welding of AA2024-T3 sheets. Two types of roller configurations were used. First, a single roller located at the rear of the tool which passed over the weld region and secondly, two rollers were located next to the weld zone symmetrically. Subsequently, several experiments comprising residual stress, distortion and fatigue crack growth (FCG) measurements were carried out combined with microstructure, texture, hardness and tensile tests. Results demonstrated that a single roller ISRT effectively diminished residual stress in the nugget zone (NZ) from + 11.7 MPa to −45.3 MPa accompanied by better weld FCG resistance. Apart from residual stress reduction, the improved weld fatigue performance was likely correlated with the modifications of weld microstructure and texture due to rolling tensioning.

Enhanced Durability of Wood Cutting Tools through Thermal Cycling.

This study investigates the impact of multi-step austenitization heat treatment on the in-service life of modified AISI A8 cold work tool steel knives used in wood cutting. The knives were subjected to two treatment methods: single quenching and double tempering (SQDT) and double quenching and double tempering (DQDT). Both treatments were followed by physical vapor deposition (PVD) coating to enhance surface properties. The DQDT treatment resulted in a finer microstructure and more uniform carbide distribution. Field tests on 24 knives over 124 h demonstrated up to 130% improvement in wear resistance for DQDT knives, along with superior edge stability and better PVD coating preservation. DQDT knives exhibited ductile fractures characterized by dimples, contrasting with the brittle fracture and cleavage facets in SQDT knives. Residual stress measurements showed higher compressive stresses in DQDT knives (-280 MPa) compared to SQDT knives (-30 MPa), which increased further after field testing. The enhanced performance of DQDT knives is attributed to their refined microstructure, improved carbide distribution, and higher compressive residual stresses, offering significant potential for improving wood cutting tool efficiency and durability.

Three-dimensional polarimetric ptychography

A three-dimensional polarimetric ptychography (3D-PP) technique is proposed to reconstruct the residual stress distribution in optical elements in three dimensions by combining polarization imaging and a 3D ptychographic iterative engine (3D-PIE). 3D-PP mainly uses two orthogonal linear polarizers placed along the light direction to capture the photoelastic information within an optical element. Based on phase shift theory, a three-step phase shift method is proposed to record three dark field images, allowing for calculating the isometric line of residual stress within the optical element. This method enables the layer-by-layer measurement of residual stress within thick samples and assesses the distribution of residual stress along the detection axis, enhancing the precision of stress measurements.

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.

Adaptively remeshed multiphysical modeling of resistance forge welding with experimental validation of residual stress fields and measurement processes

Welding processes used in the production of pressure vessels impart residual stresses in the manufactured component. Computational modeling is critical to predicting these residual stress fields and understanding how they interact with notches and flaws to impact pressure vessel durability. In this work, we present a finite element model for a resistance forge weld and validate it using laboratory measurements. Extensive microstructural changes, near-melt temperatures, and large localized deformations along the weld interface pose significant challenges to Lagrangian finite element modeling. The proposed modeling approach overcomes these roadblocks in order to provide a high-fidelity simulation that can predict the residual stress state in the manufactured pressure vessel; a rich microstructural constitutive model accounts for material recrystallization dynamics, a frictional-to-tied contact model is coordinated with the constitutive model to represent interfacial bonding, and adaptive remeshing is employed to alleviate severe mesh distortion. An interrupted-weld approach is applied to the simulation to facilitate comparison to displacement measures. Several approaches are employed for residual stress measurement in order to validate the finite element model: neutron diffraction, the contour method, and the slitting method. Model-measurement comparisons are supplemented with detailed simulations that reflect the configurations of the residual-stress measurement processes themselves. The model results show general agreement with experimental measurements, and we observe some similarities in the features around the weld region. Factors that contribute to model-measurement differences are identified. Finally, we conclude with some discussion of the model development and residual stress measurement strategies, including how to best leverage the efforts put forth here for other types of related weld problems.

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.

The effect of productive and quality deposition strategies on residual stress for Directed Energy Deposition (DED) process

In the Directed Energy Deposition (DED) realm, challenges persist concerning process stability and mechanical properties in as-built components. Facts like inconsistent laser head feed rate and accumulated heat during multi-layer deposition result in variations in melt pool energy, causing variant clad widths and heights. Moreover, significant residual stress in as-built DED parts can induce excessive distortions and cracking. To tackle these challenges, offline energy control systems that adjust laser power or feed rate have been implemented to manage melt pool energy and improve productivity. Additionally, an innovative online clad height compensation system has been developed to achieve global height geometry, further boosting productivity. However, the impact of these productive and quality control systems on the mechanical properties of austenitic stainless-steel parts, specifically residual stress, remains unexplored. In this research, residual stress measurements in as-built DED thin wall parts fabricated with energy and/or height control strategies using neutron diffraction have been investigated. The control of three key DED parameters influencing residual stress distribution and magnitude has been identified and discussed. Measurements indicate that neither offline energy control nor online height control adversely affects the quality of the thin wall parts and offline LP-based energy control can reduce residual stress magnitude and its variation. Additionally, the height control results in compressive residual stress with elevated magnitudes. Furthermore, aggressive DED parameters hold the potential for further improvement by pairing with an energy control strategy. This study establishes a foundation for further developing comprehensive control strategies designed to enhance the productivity and quality of DED systems.

Mechanical and metallurgical assessment of a submerged arc welded surfaced rail

The surfaces of rails are often damaged during constant loading, so it is essential to repair the damaged areas in a railroad network to get the best performance. However, the traditional methods of improving rails are expensive, time-consuming, and require excessive effort. Therefore, some creative ideas would be helpful in this process, one of which may be on-site overlay arc welding instead of exchanging the whole part of the rail. In this paper, the performance of such a method is assessed experimentally, and its results are interpreted.For the investigation, a worn part of the 136RE rail, used in the freight railway network in the U.S., was chosen. After milling and flattening the surface of the rail, a submerged arc welding process was applied to rebuild this rail by utilizing a 1/8-in Lincore 40-S depositing wire. This study used four destructive tests: 1) XRD residual stress measurement, 2) SEM/OM analysis, 3) hardness test, and 4) tensile test. The results showed that the required mechanical strength could be achieved. However, the repaired area seems more vulnerable to the forces encountered on a railroad network due to the more brittle structure due to high temperatures in this region. Considering this flaw is critical because forces are primarily dynamic in railway networks, especially in heavy rails, which are higher due to the extensive use of freight trains.

Rapid carburizing of low-alloy steel by atmospheric-controlled induction-heating fine-particle peening and investigation of its fatigue properties

Atmospheric-controlled induction-heating fine-particle peening (AIH-FPP) was applied to low-alloy, low-carbon steel AISI 4120 to achieve rapid carburizing within minutes and enhance fatigue strength. The shot particles used during AIH-FPP were specifically created by mechanically milling a mixture of steel particles and carbon powders. The specimens were analyzed using laser microscopy, optical microscopy, X-ray diffraction for residual stress measurement, a micro-Vickers hardness tester, and an electron probe micro-analyzer. Axial fatigue tests and fracture surface analyses via scanning electron microscopy and energy-dispersive X-ray spectroscopy were also conducted. AIH-FPP effectively transferred carbon to the treated surface and facilitated its diffusion in a short period, creating a martensite layer with high hardness and compressive residual stress, which resulted in increased fatigue strength. The fatigue strength of the AIH-FPP-treated specimens was influenced by the conditions of reheating and quenching, which altered the prior austenitic grain size and stress concentration at the specimen surface. Notably, specimens treated with AIH-FPP followed by reheating and water-injection quenching exhibited fatigue strength comparable to that of conventional gas-carburized specimens, owing to the formation of a carburized layer with a small prior austenite grain size.

Calibration Method of Measuring Heads for Testing Residual Stresses in Sheet Metal Using the Barkhausen Method.

Among non-destructive testing methods, a group dedicated to the assessment of the state of residual stresses can be distinguished. The method of measuring residual stresses using the Barkhausen noise method has many advantages, as evidenced by the number of publications. The residual stresses in metal products are important for the further processing of such metal, such as laser cutting or bending. The results presented in this work are of an experimental nature, and the presented method of calibration of measuring heads shows how various research techniques can be used to correlate results. The research was carried out for structural steel due to the market share of this type of steel. The method can be used to measure the residual stresses in ferromagnetic metal products in order to assess their directions and quantify them. A prerequisite for the use of this measurement method is that the amplitude and geometry of the Barkhausen noise are adequately correlated to the specific values of the state of stress depending on the tested steel grade or other metals. In this study, a method for calibrating measuring sensors for the residual stress measurements is presented, as developed by the authors. The method involved conducting bending tests in both numerical modeling and experimental tests. During the bending tests, changes in the magnetic field (Barkhausen noise waveform) were recorded, taking into account the state of elastic stresses. Correlating the results of the numerical calculations and Barkhausen noise measurements made it possible to determine the quantitative values of the residual stresses in the steel sheets. Thanks to the method used, very accurate measurement is possible, and the obtained results are repeatable.

Validation of Hole-Drilling Residual Stress Measurements in Workpieces of Various Thickness

BackgroundA recent revision to the ASTM E837 standard for near-surface residual stress measurement by the hole-drilling method describes a new thickness-dependent stress calculation procedure applicable to “thin” and “intermediate” workpieces for which strain versus depth response depends on workpiece thickness. This new calculation procedure differs from that of the prior standard, which applies only to thick workpieces with strain versus depth response independent of thickness.ObjectiveHerein we assess the new calculation procedures by performing hole-drilling residual stress measurements in samples with a range of thickness.MethodsNear-surface residual stress is measured in a thick aluminum plate containing near-surface residual stress from a uniform shot peening treatment, and in samples of different thickness removed from the plate at the peened surface. A finite element (FE) model is used to assess consistency between measured residual stress across the range of sample thickness.ResultsMeasured residual stress varies with sample thickness, with thinner samples exhibiting smaller near-surface compressive stress and a larger gradient of subsurface stress. These trends are consistent with both observed bending (curvature) of the removed samples and the trend in FE-calculated expected residual stress. The measured and expected residual stresses are in good agreement for samples of intermediate thickness, but the agreement decreases with sample thickness. Measured residual stress is invariant with gage circle diameter.ConclusionThe new thickness-dependent stress calculation procedure for hole-drilling provides meaningful improvement compared to thick-workpiece calculations.

Enhanced adhesion and corrosion resistance through the modulation of a metallic Ti underlayer thickness

In this investigation, TiCN/TiN thin solid film was selected as a protective coating and deposited onto AZ31 alloy through reactive magnetron sputtering. To mitigate the potential failure resulting from the significant physical disparity between the ceramic film and the metal substrate, a Ti thin film was employed as a base layer. Following the deposition process, an analysis was conducted on the structural features, residual stress, fracture morphology, adhesion strength, and corrosion characteristics of the film/substrate system utilizing X-ray diffraction, scanning electron microscopy, scratch testing, and electrochemical workstation. The findings indicate that the incorporation of a Ti metallic underlayer significantly improves the adhesion and corrosion resistance of the TiCN film. However, when the thickness of the Ti layer surpasses 0.37 μm (deposition of 15 min), it leads to the formation of a distinct columnar crystal microstructure, increased residual stress, and diminished adhesion and corrosion resistance. Additionally, this study delves into the corrosion failure mechanisms in a chloride environment and explains the principles of residual stress measurement through XRD.

Microstructural and mechanical properties analysis of SS 316L structure fabricated using CMT-wire arc additive manufacturing

Integrating robotic arm technology with cold metal transfer (CMT) has revolutionized wire arc additive manufacturing (WAAM). The research work consists of the fabrication of SS 316L WAAM using the CMT technique. Investigations of mechanical and microstructural properties, i.e. residual stress measurement (RSM), microhardness (MH), ultimate tensile strength (UTS), percentage elongation (PE), and microstructure of WAAM sample and cold rolled (CR) plate, results were compared. WAAM attained an UTS of 590 MPa, with an average yield strength (YS) of around 302 MPa, exceeding the CR plate’s UTS of 557 MPa while maintaining a similar YS of 305 MPa. WAAM and the CR plate exhibited nearly identical PE, with 64% and 62% values, respectively. Residual stress analysis revealed that the WAAM sample showed an average compressive residual stress of 124 MPa, accounting for 87% of the average residual stress observed in the CR plate, which measured 142 MPa. The MH profile of WAAM revealed an average value of 230 HV0.5, accounting for 88% of the MH observed in the CR plate at 260 HV0.5. The performance of WAAM closely matched that of the CR plate in terms of residual stress and MH.

Reduction in residual stress and distortion of thin-walled inconel 718 specimens fabricated by selective laser melting: Experiment and numerical simulation

Residual stresses were induced in the fabrication of thin-walled Inconel 718 specimens through selective laser melting (SLM) due to rapid heating and cooling, which yield distortion and have a detrimental impact on their mechanical performance. Reducing the process-induced residual stress and distortion is of great importance for practical applications. For achieving this aim, accurate measurement of residual stress and distortion is required. In the present work, residual stresses of SLMed samples were measured through hole drilling method (HDM), taking into account their anisotropic features. The distortion induced by the release of residual stress after manufacturing was measured using digital image correlation (DIC). The effect of thickness of thin-walled samples on residual stress and distortion was investigated. The results indicate that by reducing the thickness of sample, the residual stress could be reduced, whereas the distortion was increased. Furthermore, it was revealed that by manufacturing a pair of side samples in one printing job, the distortion and residual stress of the thin-walled component fabricated by SLM can be evidently reduced. The obtained results were clarified by using thermal-mechanical simulations of SLM.

Measurement of Internal Residual Stress of Three-Directional Components and Estimation of Inherent Strain in Carburized Steel for Large Rolling Bearings by Combining the Contour Method and XRD Method

Measurement of Internal Residual Stress of Three-Directional Components and Estimation of Inherent Strain in Carburized Steel for Large Rolling Bearings by Combining the Contour Method and XRD Method