Residual Stress Distribution Research Articles

Numerical Study to Analyze the Influence of Process Parameters on Temperature and Stress Field in Powder Bed Fusion of Ti-6Al-4V

This paper presents a comprehensive numerical investigation to simulate heat transfer and residual stress formation of Ti-6Al-4V alloy during the Laser Powder Bed Fusion process, using a finite element model (FEM). The FEM was developed with a focus on the effects of key process parameters, including laser scanning velocity, laser power, hatch space, and scanning pattern in single-layer scanning. The model was validated against experimental data, demonstrating good agreement in terms of temperature profiles and melt pool dimensions. The study elucidates the significant impact of process parameters on thermal gradients, melt pool characteristics, and residual stress distribution. An increase in laser velocity, from 600 mm/s to 1500 mm/s, resulted in a smaller melt pool area and faster cooling rate. Similarly, the magnitude of residual stress initially decreased and subsequently increased with increasing laser velocity. Higher laser power led to an increase in melt pool size, maximum temperature, and thermal residual stress. Hatch spacing also exhibited an inverse relationship with thermal gradient and residual stress, as maximum residual stress decreased by about 30% by increasing the hatch space from 25 µm to 75 µm. The laser scanning pattern also influenced the thermal gradient and residual stress distribution after the cooling stage.

Effect of shot peening on microstructural features, residual stress behavior, and hardness of aluminum alloy 2014

Abstract The current study investigates the effect of shot peening on the microstructural features, residual stress distribution, and surface hardness of aluminum alloy 2014, which is essential for applications in aerospace, automobile, and structural components requiring improved fatigue life and wear resistance. Microstructural analysis reveals significant grain refinement (6.6 µm) in the treated specimen and fragmentation of Al₂Cu precipitates, reducing their size from 1.9 µm in the untreated specimen to 0.6 µm in the treated specimen. X-ray diffraction confirms grain refinement and increased dislocation density in the shot-peened alloy, evidenced by enhanced peak intensities and slight broadening. Residual stress measurements show a shift from near-neutral stresses in the untreated alloy to compressive stresses in the shot-peened layer, with a peak stress of -313.1 MPa at the surface, transitioning to tensile stresses at deeper layers. Surface hardness analysis shows a substantial increase to 131.5 HV near the surface, compared to 115 HV in the untreated specimen, due to work hardening, grain refinement, and induced compressive stresses.

Multiscale Mechanical Study of Proanthocyanidins for Recovering Residual Stress in Decellularized Blood Vessels.

Decellularized artificial blood vessels prepared using physical and chemical methods often exhibit limitations, including poor mechanical performance, susceptibility to inflammation and calcification, and reduced patency. Cross-linking techniques can enhance the stiffness, as well as anti-inflammatory and anti-calcification properties of decellularized vessels. However, conventional cross-linking methods fail to effectively alleviate residual stress post-decellularization, which significantly impacts the patency and vascular remodeling following the implantation of artificial vessels. This study enhances vascular residual stress through varied conditions of proanthocyanidin (PC) cross-linking on decellularized vessels. Microstructural analysis and mechanical investigations across various scales of fresh, decellularized, and residual stress-recovered vessels are performed using atomic force microscopy (AFM), scanning electron microscopy (SEM), and uniaxial tensile testing. Results demonstrate substantial alterations in the morphology of elastic and collagen fibers post-decellularization, which remarkably resemble fresh vessels following residual stress recovery. Furthermore, both the micro- and macro-mechanical characteristics of vessels post-residual stress recovery, including Young's modulus, viscoelasticity, and adhesion, closely resemble those of fresh vessels. Finite element modeling (FEM) confirms the distribution of residual stress and its role in enhancing vascular mechanical integrity. This experimental investigation provides a theoretical foundation at both micro and macroscopic levels for the development of biomimetic blood vessels.

Study of residual stress and residual deformation of T-joints by continuous simultaneous double-sided welding

This paper investigates both the magnitude and distribution of temperature field, residual stress and deformation of DH36 steel fillet welded T-joints through the numerical simulation method. A thermal elastic-plastic finite element analysis is performed to investigate the heat transfer and deformation mechanisms during the welding process, employing a DFLUX subroutine developed in ABAQUS based on the double-ellipsoidal heat source model. The effects of welding speed and power on residual stress and deformation are further investigated. The finite element simulation results show good agreement with experimental measures regarding temperature distribution, melt pool morphology, residual stress, and deformation distribution. The results show that welding speed and power significantly affected the temperature variation during the welding process, which further influence the distribution of residual stress and residual deformation. The results indicate that high power at low welding speeds producing high temperatures leads to bottom fusion, while low power at high welding speeds resulted in insufficient fusion depth. Therefore, selecting appropriate welding speed and power is crucial for ensuring weld quality.

Simulation of residual stress and distortion evolution in dual-robot collaborative wire-arc additive manufactured Al-Cu alloys

ABSTRACT The aim of this study is to evaluate the residual stress and deformation distribution of large thin-walled Al-Cu alloy components produced by a dual-robot collaborative system in wire-arc additive manufacturing. Finite element models of single-robot and dual-robot systems were developed and experimentally validated using infrared thermography and structured light sensors. The dual-robot achieved significantly lower maximum temperature gradients in both deposition (0.47 × 105 ℃/m vs. 0.68 × 105 ℃/m) and height directions (0.94 × 105 ℃/m vs. 1.03 × 105 ℃/m) compared to the single robot, indicating more uniform temperature distribution. The stress evolution process and distribution between the single robot and dual-robot systems differs, but both exhibit approximately symmetric distributions. Moreover, the dual-robot reduced vertical displacement in the substrate by approximately 29% (15.2 vs. 21.4 mm), attributable to more uniform stress distribution and reduced temperature gradients. The additive manufacturing of a commercial aircraft load-bearing frame validated the application potential of this technology in the industry.

Crack Arrest Analysis of Components With Compressive Residual Stress

ABSTRACTA finite element analysis and fracture mechanics methodology for determining the autofrettage pressure required to cause crack arrest in components under varying pressure loading are presented. Superposition of the autofrettage residual stress distribution and working load stress distribution is combined with ANSYS Separating Morphing and Adaptive Remeshing Technology (SMART) to determine the effective stress intensity factor as the crack grows. The condition for crack arrest is identified by comparison with a crack arrest model defining the crack propagation threshold stress intensity factor range for microstructurally short, physically short, and long cracks. The crack propagation threshold models of El Haddad and Chapetti are implemented and applied to fatigue analysis of stainless steel and low carbon steel double notch tensile test specimens with preinduced compressive residual stress. Based on comparison with fatigue test results, the Chapetti model is selected for use in the analysis of a 3D aluminum alloy valve body. The calculated minimum autofrettage pressure required to give crack arrest under a given working load cycle is found to be in good agreement with experimental observations from the literature.

Control of the size and distribution of residual macronapples by rolling rollers

Abstract. To increase the fatigue strength of parts, surface plastic deformation (SPD) is used by rolling. This creates a residual stress state that affects the fatigue strength of parts. This paper shows the possibility of controlling the level and distribution of residual macrostresses in the surface layer of parts by rolling. This makes it possible to optimize the modes of PPD for critical, heavily loaded parts subjected to cyclic loads during operation. Problem. Controlling the magnitude and distribution of residual macro-stresses, which will increase their stability during cyclic loading of parts and, as a result, increase the fatigue strength of parts after hardening of the PPD. Goal. Study of the formation of residual stress state and control of the magnitude and distribution of residual macro-stresses. Methodology. To solve this problem, macrostresses were determined by the X-ray method. The advantage of this method is its localization, the ability to analyze the distribution of residual stresses in depth. It is the use of this advantage of the method that made it possible to identify features in the distribution of residual stresses on the surface and in the depth of the hardened layer of parts after rolling. Originality. The ability to control the level of residual stresses in the surface layer. Practical value. By changing the pumping modes, it is possible to ensure the required level of residual stresses on the surface and create the required residual stress distribution pattern over the depth, there by increasing the efficiency of the SPD.

Dimensional Analysis and Validity of Uniaxial Residual Stress Distribution for Welded Box Sections

This paper investigates the residual stresses induced by metal inert/active gas (MIG/MAG) welding in normal strength steel box sections, focusing on the validity of uniaxial residual stress assumption. Advanced manufacturing simulations are conducted using deterministic uncoupled transient thermomechanical analysis with a double-ellipsoidal heat source model, employing 8-node solid elements and material models calibrated for extreme temperatures per EN 1993-1-2. A comprehensive parametric analysis investigates the effects of primary welding variables, such as heat source power and welding speed, alongside geometric parameters of the heat source model using random Latin hypercube sampling technique in the analyzed parameter set. The relationship between the size and shape of the characteristic isotherms, i.e., the aspect ratio and the Rosenthal number, underscores that the analyzed welding heat sources are in the fast regime with the validity of uniaxial residual stresses based on the analytical assumption (minimal values are AR = 9.94 and Ro = 30.47). The validity and limitations of uniaxial residual stress assumptions for 59 welded and 51 heated box sections are critically evaluated by using the finite element model-based stress triaxiality parameter. Results confirm that longitudinal residual stresses dominate typical MIG/MAG welding applications, supporting the application of uniaxial residual stress models in advanced structural design by neglecting in-plane and through-thickness residual stresses. Conversely, three-dimensional residual stress state dominates under conditions such as preheating or thermal straightening.

Effects of Vibratory Stress Relief on Microstructure and Mechanical Properties of Marine Welded Structures

Dissimilar steel welded structures are commonly used in the marine engineering field. Owing to the scarcity of in-depth investigation into the intricate pattern of residual stress distribution in welding within 316L/Q345 dissimilar steel welded joints and methods for reducing this stress, a platform-based vibratory stress relief (VSR) experimental system was established to comprehensively study the effects of VSR on the mechanical properties and microstructure of 316L/Q345 welded structures. Scanning electron microscopy (SEM) was used to examine the fracture morphology and explore the intrinsic mechanisms by which VSR enhances the mechanical properties of welded joints. The findings suggest that VSR is capable of significantly homogenizing and diminishing the welding residual stress within the heat-affected area of 316L/Q345 mismatched steel welded specimens. The significant reduction in residual stress after VSR can primarily be attributed to the combination of alternating stress applied by the VSR platform and the welding residual stress, which exceeded the yield limit of the metal materials. Furthermore, the significant reduction in residual stress, refinement of second-phase particles, and changes in fracture mechanisms are the main reasons for the increased strength observed after VSR. This study has significant engineering application value, providing a theoretical basis for the use of VSR treatment to enhance the reliability of the safe operation of marine engineering equipment.

Analysis and Simulation Research on Static Softening Mechanism Following Multistage Hot Deformation of 1.3 GPa Grade Bulb Flat Steel

In this study, the flow stress behavior of 1.3 GPa grade bulb flat steel (BFS) is studied under different deformation temperature and strain rate using the Gleeble‐3800 thermomechanical simulator, and the Arrhenius‐type constitutive equation is established. A static recrystallization kinetics model of 1.3 GPa grade BFS is established based on double‐pass hot compression tests. The established constitutive equation and static recrystallization kinetics model are embedded into the finite‐element model of the hot‐rolling process, and the static recrystallization and residual stress distribution between each pass are analyzed. In the results, it is indicated that static softening happens rapidly after the end of the pass, and then the speed gradually slows down. Reasonably controlling the interval time between each pass helps to fully utilize the effect of static softening relaxation residual stress. After the K12–K8 and K7–K2 passes, the rolled pieces can undergo fully static recrystallization after being heated for 5 and 8–11 s, respectively, eliminating residual stresses during hot rolling and reducing the impact on plate shape. The results give data support for the optimization of the hot‐rolling process of 1.3 GPa grade BFS. It provides a new way to control the shape accuracy of hot‐rolling‐section steel.

Residual Stress Characteristics in Spot Weld Joints of High-Strength Steel: Influence of Welding Parameters

This study examines the residual stress characteristics of spot welding in newly developed high-strength steel for automotive body construction through experimental and numerical methods. The effects of sheet thickness, nugget size, and the presence or absence of spacers on residual stress distribution and fracture stability were evaluated. Measurements using XRD and HDR revealed tensile residual stress below the yield strength at the nugget center. A numerical analysis system corroborated experimental findings, demonstrating that larger nugget sizes reduce tensile residual stress at the nugget center, enhancing fracture stability. However, for nugget sizes of 3 (t: thickness), high tensile stress at the nugget edge compromised stability, while sizes of 3.5 or larger improved fracture resistance. The study also found that thicker sheets increased fracture safety with larger nugget sizes, and the presence of spacers induced tensile stress through spring-back effects, which shifted to compressive stress as the nugget size increased. These results provide critical insights into optimizing welding parameters to improve the structural integrity of automotive components.

High-speed laser-directed energy deposition of crack-free wear-resistant and anti-corrosive Al/Cu bimetal components

ABSTRACT Al/Cu bimetal components (BMCs) possess higher thermal conductivity, better wear resistance and corrosion resistance than Al and Al alloys. It is a big challenging task to fabricate a high-performance Al/Cu BMC by a conventional infrared (IR) laser-directed energy deposition (L-DED) process due to the crack formation and high IR laser reflectivity. A novel high-speed L-DED process was proposed to successfully fabricate a crack-free Al/Cu BMC by controlling the residual stress distribution and brittle intermetallic compounds (IMCs) formation. The damaging effect of the reflective IR laser rays on the laser equipment can also be suppressed. Compared with the Al base metal, the microhardness, wear and electrochemical corrosion performances of the Al/Cu BMC were significantly improved. The residual stress distribution was predicted and measured. The IMC formation mechanism was revealed based on element distributions, the formation energy and the effective heat of formation of each IMC. The study would provide the basis for manufacturing crack-free and high-performance multi-material components in many applications in different industries.

Thermal and residual stress analysis of multi-pass welded stainless steel pipes using DEFLUX and FILM subroutine

This study presents an in-depth investigation of the influence of welding parameters (welding speed and number of passes) on the residual stress distribution in AISI 304 (Z7CN18-09) austenitic stainless-steel tubes. A three-dimensional finite element modeling (FEM), developed in ABAQUS, was implemented to simulate the circumferential welding process. The DFLUX and FILM subroutines were implemented to model the double ellipsoid mobile heat source and thermal boundary conditions, respectively. Model validation was performed by comparing weld bead profiles and thermal cycles with experimental results, showing excellent correlation (deviation < 5%). The coupled thermal and mechanical analyses allowed evaluation of the spatiotemporal evolution of the temperature field for different welding speeds (80-160-240 mm/min) and the distribution of axial and circumferential residual stresses as a function of tube thickness. The numerical results demonstrate a significant influence of these parameters on the amplitude and distribution of residual stresses, with a notable reduction in maximum stresses for optimized welding speeds and better stress homogenization with multi-pass welding.

Deep Rolling Process Modeling Using Finite Element Analysis in Residual Stress Measurement on Rail Head UIC860 Surface

This study investigates the effects of deep rolling parameters, pressure, speed, and offset, on the residual stress distribution and material deformation in UIC 860 Grade 900A railway rails. We will model deep rolling to simulate the process and predict the residual stress profile in railway rails. Subsequently, we will rigorously compare and analyze the FEM simulation results with experimental data to optimize deep rolling parameters for improved residual stress distribution. Using both experimental methods and finite element analysis via ANSYS 2023 R1, the study varied deep rolling parameters. Experimental deep rolling pressure was set at 150 bar, speed at 1800 mm/min, and offset at 0.1 mm, while FEA simulations predicted corresponding pressures of 157 bar and speed of 1796.52 mm/min. These parameter settings were chosen to induce significant surface compressive stresses that could enhance the material’s mechanical performance. The experimental results showed an average compressive residual stress of 498.9 MPa, closely aligning with the FEA-predicted value of 502.5 MPa. A paired t-test revealed no statistically significant difference between the two results, with a T-value of −0.22 and a p-value of 0.833, validating the reliability of the FEA model. The consistent deformation observed in both experimental and FEA simulations, especially with a 0.1 mm offset, confirmed that the rolling parameters were effective in producing uniform stress distribution, albeit with a slightly extended processing time due to the small offset. Overall, the findings confirm that optimizing the deep rolling parameters of pressure, speed, and offset leads to favorable residual stress distributions and improved material properties. The results indicate that FEA is a reliable tool for predicting the outcomes of deep rolling, and this study provides a strong foundation for further refinement of the process to enhance performance in practical applications, such as railway rail treatments.

Numerical Study of the Effects of Residual Stress in Welded Pipe Joints

In general, welding processes can be understood as the establishment of the union of parts, generally metallic, using a heat source to promote the fusion of materials, with or without the presence of pressure efforts. Studies related to the distributions and levels of residual resistance arising from the thermal cycles involved in welding processes are of vital importance for evaluating and guaranteeing the integrity of welded pipes. This work proposes the implementation of a routine in PYTHON language to automate the production of thermomechanical coupling welding models using the ABAQUS® CAE finite element tool, considering the heat distribution model of the welding source according to Goldak et al. (1984), better known as the double ellipsoid model. The studies are produced considering an ambient temperature of 20 °C and another with preheating of the tubes to 300 °C. The results achieved by this study are related solely to analyzes of the residual stress fields in a thin walled tube joint manufactured in AISI 304 stainless steel, welded using TIG (Tungsten Inert Gas) processes in a single pass. Thus, this study seeks to analyze the hoop and axial residual stress distributions on the internal or external walls of post-welded tubes in angular positions 0°, 90°, 180° and 270°, whether or not there is uniform preheating of the pre-welding pipes. The results show that, in general, residual stresses differ slightly with the angular position, being relatively high when compared to the yield stress of the steel, and therefore have a considerable impact on reducing the mechanical strength of the welded joint. It should also be noted that when considering the preheating of the pipes there is a significant decrease in the peak temperatures reached in the transfer process, in the cooling rates and in the residual stress levels of the joints, especially in the most critical regions, located in the proximity from the center of the weld beads.

Effect of scanning strategy on the thermo-structural coupling field and cracking behavior during laser powder bed fusion of Ti48Al2Cr2Nb alloys

Laser powder bed fusion (LPBF) is characterized by complicated non-equilibrium processing characteristics, involving extremely high temperature gradient and cooling rate within the mesoscopic dynamic molten pool, which brings great challenges to the forming of metal materials with high crack sensitivity (such as γ-TiAl alloy). In this paper, based on the LPBF forming process of Ti48Al2Cr2Nb alloy, a corresponding multi-track and multi-layer thermal-structure sequential coupled finite element model was constructed, and the influence of four different scanning strategies on the temperature and stress evolution behavior in the powder bed forming region was quantitatively studied, and the crack initiation criterion was also established according to the relationship between nodal flow stress and equivalent stress. It was found that island scanning strategy could induce the higher molten pool temperature and attendant larger molten pool size compared with the non-island linear scanning strategy. Besides, island scanning strategy was conducive to relieving the thermal stress inside the division region but also inducing the stress concentration in the sub-island overlap region. Specially, the strip island scanning strategy exhibited the lowest residual stress and most homogeneous stress distribution. By the experimental measurements, the strip island scanning strategy contributed to the lowest crack density of 0.33mm/mm2.

Microstructure and residual stress distribution of dissimilar joints of SS321 to Hastelloy C-276 using CO2 Laser Beam Welding: An experimental validation

This study applies a 3D model built for butt dissimilar joints welded using a laser beam. The thermo-mechanical study of SS321 and Hastelloy C-276 uses a volumetric Gaussian heat source model. Ansys parametric design language code is executed in ANSYSTM software for the simulation. Using the CO2 laser beam welding procedure, the simulation’s parameters serve as the experimental input procedures. We employ x-ray diffraction methods to quantify residual stresses in the weldments and evaluate the joint quality. The thermal results show that the fusion zone experiences maximum temperature, and the conduction occurs on the SS321 side. The residual stresses are tension at the fusion zone for simulation and experimentation. The welds exhibited full penetration and a consistent “Y” shape across all samples, indicating good structural integrity without internal defects. The factor of safety from the Finite Element Analysis (FEA) is 1.73, and the experimentation is 2.20. The residual stress varies by 21% from measured and FEA. Studies were carried out to characterize the weldments for their mechanical and metallurgical properties. Tensile tests confirmed that the weld zone’s strength is higher than the parent metals.

Residual stress distributions of trapezoidal corrugated web I-members: Experimental and numerical study

This study utilized the hole-drilling method to determine the residual stress distribution in the sections of trapezoidal corrugated web I-members (TCWM). Then, using ABAQUS software, welding simulations and a parameter study of the longitudinal residual stress distribution for TCWM sections are conducted. Finally, a distribution model of the longitudinal residual stress for TCWM sections are proposed. The research findings indicate that the existing residual stress distribution models for flat web I-sections are unsuitable for predicting the residual stress distribution in TCWM sections. Moreover, the longitudinal residual stress distribution in the flanges of TCWMs varies with the position of trapezoidal corrugated webs (TCW). Specifically, the maximum residual tensile stress in the flanges with the parallel web fold surpasses that of the inclined web fold by approximately 10 %. With an increase in corrugation angle, the range of residual tensile stress in the flanges increases. Unlike the flat web of I-sections, there is almost no longitudinal residual stress in the middle area of the TCWs. The proposed models of residual stress distribution for TCWM sections consider the influence of corrugation and cross-sectional dimensions and align well with both experimental and numerical results.

Influence of Initial Yield Strength Weighting on Residual Stresses in Quenched Cylinders Using Finite Element Analysis.

Using the quenching process to create a specific residual stress distribution in steel parts is a key method for improving their strength. Although finite element simulation can overcome the time-consuming and labor-intensive limitations of experimental measurements, accurately predicting the residual stress distribution in quenched steel parts remains a challenge for researchers and manufacturers. The initial yield strength weighting scheme used in finite element simulations has a significant impact on the results. To investigate the influence of initial yield strength weighting on the residual stress distribution in quenched steel cylinders, finite element models with different yield strength weightings have been developed. The results show that the large hardness difference between austenite and martensite can cause significant deviations between the residual stress predicted using linear weighting and the experimental results. The linear weighting scheme commonly used by researchers overestimates the yield strength of the austenite phase in the mixed-phase material during cooling, leading to an overestimation of residual stress. Employing nonlinear yield strength weightings, such as Leblond weighting, can significantly improve the computational accuracy of finite element models, yielding more reliable and consistent predictions. This improved accuracy in predicting residual stress using finite element simulation offers a powerful tool for optimizing the quenching process.

Formation of Residual Stress Diagram after Quenching in a Magnetic Field

Introduction. After hardening, a product has residual stresses: structural and thermal. The magnitude of the total stresses in the finished part determines its crack resistance under the influence of operational loads. Quenching in a constant magnetic field affects the process of martensite nucleation, and the kinetics of martensite transformation, as well as the processes of martensite decomposition. However, there is currently no data available on how these changes in structure affect the stress diagram in a heat-treated product. The aim of this study was to investigate the influence of a constant magnetic field during hardening of iron-carbon alloys on the stress distribution across the cross-sectional area of parts.Materials and Methods. The studies were conducted on samples of technical iron, steel 45, and ferritic malleable cast iron. Cylindrical samples with a diameter of 16 mm and ring samples with an outer diameter of 20 and 55 mm were used. The samples were heated in an electric furnace or an induction heating lamp generator LZ-13, and quenched in water or mineral oil. A constant magnetic field with strength of 768 to 1600 kA/m during hardening was created in the bore of a FL-1 electromagnet. Residual stresses were determined using the original method developed by V.A. Blinovskii based on measuring bending deformations in hollow bodies of revolution.Results. The change in temperature on the surface, in the core, and the temperature difference across the cross-section of a cylindrical sample during cooling in water with and without a magnetic field was obtained. The distribution of stresses over the cross-section after quenching with and without a field for industrial iron in still water was studied. The stress distribution over the cross-section was studied after quenching in a field and without a field in calm water, as well as during spray cooling of steel 45 and ferritic ductile cast iron at different rates.Discussion and Conclusion. The obtained calculated and experimental data allowed us to evaluate possible changes in the residual stress diagrams under the influence of a magnetic field after quenching with volumetric and surface heating. A study of the kinetics of cooling in water under the influence of a magnetic field showed that the temperature difference across the cross-section remained practically unchanged, but there was a decrease in the cooling capacity of the water, which contributed to a reduction in the level of thermal stress. Hardening in a magnetic field led to a reduction of residual stresses in iron-carbon alloys. The change in the distribution of total residual stresses during magnetic tempering was due to a change in their structural component. The magnetic field influenced the distribution of structural, thermal and total residual stresses. The reason for the observed effects was the change in the structural state of steel and cast iron and the cooling ability of water-based quenching liquids under the influence of a magnetic field. The reduction of the level of residual stresses during heat treatment in a magnetic field reduced the likelihood of brittle fracture and cracking, led to a decrease in deformation and warping of hardened steels, and created favorable conditions for the operation of parts under conditions of alternating loads and abrasive friction.