Distribution Of Residual Stress Field Research Articles

Evidence of microstructural evolution linked to non-monotonic distribution of micromechanical properties induced by shot peening

The residual stress field induced by surface strengthening processes such as mechanical shot peening and other forms of plastic deformation does not generally exhibit a simple “monotonic” distribution trend. Some researchers have analyzed this fact from a mechanical perspective based on Hertz theory. However, the micro/nano-scale microstructural changes corresponding to the distribution of residual stress fields still appear to be lacking. In this study, we focused on a widely used material in aviation manufacturing, namely nickel-based superalloy GH4169, as our experimental material. We subjected GH4169 alloy to mechanical strengthening treatment using a shot peening intensity of 0.25 mmA, followed by quantitative testing of micromechanical performance indicators such as microhardness and residual stress. To thoroughly investigate the relationship between micromechanical properties and microstructure changes, we utilized transmission electron microscopy (TEM) to observe and analyze shot-peened materials at different depths. Our findings revealed that the most severe microstructural distortion induced by mechanical shot peening in GH4169 alloy was likely to occur within a depth range of 25 to 75 μm. This observation aligns with the actual phenomenon that the maximum microhardness and maximum residual compressive stress did not manifest on the outermost surface of the material. By presenting a detailed analysis of deformation defects such as dislocations, stacking faults, and twinning in different depths of mechanically strengthened layers, our study contributes to a deeper understanding and practical application of post-processing technologies based on plastic deformation.

Simulation study on effect of flame cutting speed on temperature field and residual stress distribution

Due to the advantages of flame cutting in thick plate cutting and cutting cost, it is widely used in the metal cutting process of shipbuilding and machinery manufacturing. But at the same time, the local heating of flame cutting will cause residual stress inside the steel plate. Residual stress is an important reason for deformation and cracking of components. The change of temperature field is the premise of affecting the distribution of residual stress. Cutting speed has an important effect on the distribution of temperature field and residual stress field. In this paper, ABAQUS is used to create a finite element model for flat flame cutting of Q345D low-alloy steel. Based on the working principle of flame cutting, the model of flame cutting composite heat source is established and the subprogram of composite heat source is written. The thermal-mechanical direct coupling method is used to simulate and analyze the effect of different cutting speeds on the temperature and residual stress field distribution of the flat flame cutting process, to provide a reference for the subsequent processing.

Effect of surface strengthening by ultrasonic shot peening on TC17 alloy

This paper investigates the effects of ultrasonic shot peening (USP) on surface morphology, microstructure, and residual stress field distribution of TC17 alloy under different process parameters. The aim is to reveal the surface strengthening mechanism of TC17 alloy caused by USP. The results suggest that the use of the 2.5 mm projectile diameter leads to an increase in surface roughness, plastic deformation, and a deeper grain refinement layer compared to the 1.5 mm projectile diameter. Additionally, it results in a greater depth of the compressive residual stress layer and maximum compressive residual stress. The crack initiation sites under two projectile diameters are located below the compressive residual stress layer. The USP treatment introduces compressive residual stress on the surface, inhibiting the initiation of surface cracks, and the deeper compressive residual stress layer offsets the early fatigue failure caused by higher roughness.

Two laser beam modulation of microstructure and residual stress field in cold sprayed Al alloy for recovering fatigue performance

The cold spray (CS) process has been demonstrated to be an attractive additive manufacturing technology for the development of freeforms and coatings from temperature-sensitive materials. However, owing to the lower bonding strength and inhomogeneous residual stress field distribution, the fatigue performance of CS deposition cannot satisfy the requirements of numerous engineering conditions. This study proposes a novel and promising approach to recover the fatigue performance of CS-repaired Al alloy components using two laser beam modulations. In the treatment, a millisecond laser is used during the CS process to heat the impact location in situ, by which the bonding mode is transformed from mechanical bonding to metallurgical bonding, and massive Al2O3 reinforcements of nano/micro size are formed in the coating. Thus, the bonding strength is significantly improved. Next, another nanosecond laser is used as a post-treatment to act on the area except the repaired region of the sample, which optimised the residual stress distribution around the repaired zone by the mechanical effects of the laser-induced ultra-high shock waves. Through the combination of these two lasers, the fatigue performance of CS-repaired Al alloy samples is successfully restored to its original condition. This study demonstrates that this compound process of CS technology and laser processing presents a wide range of possibilities for further development of advanced repair technology.

Heterostructure effect at the interface of maraging steel deposited upon carbon steel via directed energy deposition

To study the mechanical behavior of the interface region that appears when dissimilar metals are deposited by additive manufacturing process, maraging steel was deposited on S45C carbon steel via directed energy deposition. A 3.3 mm-thick plate obtained from the deposition containing four different regions in the vicinity of the interface (substrate/HAZ/dilution layers/feed material) was subjected to uniaxial tensile deformation parallel to the interface. The strength of the layered structure exceeded the theoretical strength calculated through the rule of mixture, while elongation to failure was almost the same as the carbon steel and yield point phenomena disappeared. The synergetic heterostructure effect of the layered structure was attributed to the formation of strain gradient and back stress strengthening effect due to the mechanical incompatibility between each region in the layered structure. Applying 220 °C preheating reduced the layered structure's elongation by assigning different strengths and residual stresses to each layer. The current result suggested that the mechanical incompatibility between domains in the interface region, including the residual stress field distribution, should be carefully controlled to improve the mechanical behavior of the interface region.

Effect of Residual Stresses on Wheel Fatigue Life and Experimental Validation

Steel wheels, consisting of rims and spokes, are important load-bearing parts of vehicles, and the fatigue fractures’ life estimation accuracy directly determines the stability and safety when applied in the transportation industry. The most common form of failure is fatigue fracture. The strong elastic–plastic deformation during the rim roll-forming process generates a residual stress field in its surface layer, which changes the actual stress distribution in the rim when it is loaded and thus affects the fatigue life of the steel wheel. In this paper, ABAQUS software was used to establish a rim-rolling simulation model to obtain the residual stress field distribution after forming and compare it with the actual residual stress on the formed surface of the rim to verify the reliability of the model. On the basis of this model establishment, the service hazard areas and maximum stresses of steel wheels with or without superimposed residual stress fields were calculated separately, and their fatigue lives were predicted separately using the local stress-strain method. The simulation results show that the maximum stress of the rim before and after the superimposed residual stress occurs in the area of the bottom of the groove, which is consistent with the actual failure location. However, the maximum stress after superposition increased from 120.7 MPa to 332.9 MPa, and the corresponding calculated life decreased from 158,340,000 to 459,500 cycles, which is closer to the actual test results. The results of the study can provide a theoretical basis for the lightweight design and process improvement of automotive steel wheels.

Numerical investigation of the effect of hole reaming on fatigue life by cold expansion

The reaming process of a 6061 aluminum alloy plate after cold expansion with a split sleeve was simulated by the finite element (FE) method based on Abaqus/CAE, and the relationship between the reaming depths and the distribution of residual stress fields was obtained by analysis. The fatigue lives of the plates under different reaming depths were calculated using the fatigue analysis software FE-SAFE and verified by fatigue tests. The results showed that reaming after expansion increased the residual compressive stress at the hole edge on the entrance surface. In addition, the fatigue life of the specimens increased with increasing reaming depth, and the best fatigue gain of the specimen was obtained when the reaming depth was 0.5 mm.

Examination of Dynamic Strain Ageing Effects during Rapid Quenching of Inconel 718 Superalloy Disc

In this work, an experimental measurement, contour method, is implemented for an after quenching IN718 forging specimen to obtain the distribution of residual stress field. A sequentially coupled thermal mechanical finite element model is developed with the similar 3D geometry of the experimental specimen and implemented the same heat transfer boundary of the rapid quenching with the experimental condition. A thermal mechanical rate dependent continuum plasticity model for IN718 alloy, with the dynamic strain ageing (DSA) effect incorporated, is developed to study the impact of DAS effect on the evolution of residual stress during rapid quenching. The modelling predictions of residual stress are in good agreement with the contour method measurements. The impact of DSA effect is further quantified, indicating that an annular high plastic strain rate region in the core part of the disc is captured during the simulation of the quenching process.

Optimization of residual stress field in ultrasonic assisted burnishing process

Surface compressive residual stress and its penetration depth are of important characteristics of burnishing process. The higher values compressive residual stress in the surface of the treated sample can delay the fatigue crack initiation; also, the further penetration depth restricts fatigue crack propagation. However, achieving both of performance at same time needs careful selection of burnishing parameter. In the present study an optimization approach is made to maximize the value of surface compressive residual stress subjected to specified penetration depth. The analytical model of residual stress previously developed by the author is firstly modified with a cubic interval function and then used to find how the ultrasonic assisted burnishing factors i.e. static force, vibration amplitude, ball diameter and material influence the residual stress field distribution. Then the model was then incorporated with particle swarm optimization algorithm to find optimal parameter setting. Results showed that it isn't possible to maximize both the surface compressive residual stress and its penetration depth at same time. Furthermore, to have maximum value of compressive residual stress magnitude at the surface with the penetration depth of 0.5 mm, it is required to use tungsten carbide ball with 3 mm diameter; also, the static load and vibration amplitude should be selected at the values of 120 N and 14 μm. The compressive surface residual stress in optimized condition is about 110 MPa that is compatible well with the 98 MPa obtained by confirmatory experiment. Also, the maximum depth compressive residual stress for optimum condition measured by experiment is 0.7 mm while it is predicted 0.8 mm by analytical approach.

Analytical modeling of ultrasonic surface burnishing process: Evaluation of residual stress field distribution and strip deflection

Ultrasonic surface burnishing (USB) process is a promising surface enhancement technique that improves fatigue life of components by exerting work hardening and compressive residual stress of the surface layers. However, USB is a complex process in practice, and there is not an analytical model published to facilitate the design and comprehension of the process. In the present paper an analytical elastic-plastic model was developed to correlate USB process factors to residual stress field (RSF). Also, deformation of strip samples was determined in the analytical approach. Parameters such static force, ultrasonic vibration amplitude, ball material and its diameter as well as ultrasonic vibration frequency were included in the model to find how they influence the residual stress variation and strip deflection. Two types of material constitutive equation i.e. Johnson-Cook (JC) that is sensitive to strain rate as well as Chaboche hardening that is influenced by cyclic loading were considered to find which material behavior is more consistent with experimental results. The experiments have been carried out on two different materials with various initial state of residual stress field (IRSF). It was obtained from the results that residual stress field variation and strip deflection obtained by experiments are consistent well with the values derived from analytical model. Therefore, the model was comprehensively used to find how the USB process factors influence the RSF and strip deflection.

Equivalent parameters-based residual thermal stress fields modeling and design for square coated indexable cutting inserts

Residual stresses may cause coating indexable inserts to delaminate during machining. To meet the demands of long tool life, low costs, high efficiency, and accuracy in industry, it is critical to know the magnitude and distribution of residual stress fields. An equivalent parameters-based modeling method is proposed to predict residual thermal stress fields for square coated indexable cutting inserts. The parameter equivalent formulas are deduced and the finite element implementation is described. The effectiveness of the approach is verified using inserts with a single coating (e.g., titanium carbide (TiC) and titanium nitride (TiN)) and multilayer coatings (e.g., TiC/TiN) by comparison with theoretical values and experimental results. In addition, some important techniques in coated inserts design and manufacturing for coated inserts were obtained by studying influence parameters via the method. A key feature of the method is that it can provide details on all stress components to facilitate a better understanding of the stress induced during cooling of square coated indexable cutting inserts. Moreover, it would provide an important theoretical basis for the design, manufacture, and selection of coated indexable inserts, and the prediction results can be considered as the initial stress fields to evaluate the performance of inserts in high-speed machining more accurately.

Parameter optimisation analysis of laser shock processing based on Ansys LS-Dyna

Laser shock processing (LSP) treatment of Q345 steel under various parameters (peak pressure, spot diameter, number of shocks and laser pulse width) was simulated with Ansys LS-Dyna by using a variable-controlling approach to optimisation. It can be concluded that the influence of LSP on surface roughness is proved to be quite weak according to the simulation results of surface morphology. The influence of different parameters on LSP is discussed based on the residual stress field distribution of the model. The optimal effect can be achieved with a single LSP impact at a peak pressure of 3–4 GPa. By increasing the spot diameter, the residual stress field is improved mainly on the top surface, but feebly in depth. Given the hardening phenomenon of the target material, the residual stress field tends to be saturated after three impacts. Thus, three LSP impacts is the most reasonable number, and the best effect can be achieved at a laser pulse of 30 ns.

Surface integrity evolution and fatigue evaluation after milling mode, shot-peening and polishing mode for TB6 titanium alloy

Surface integrity is closely related to the service life of parts and components. Effects of four kinds of integration processes on surface integrity and fatigue life are studied. These four integration processes are M (milling), MP (milling and polishing), MPS (milling, polishing and shot-peening), and MPSP (milling, polishing, shot-peening and polishing). When roughness, micro-hardness, residual stress, micro-structure and fatigue were considered after the four integration processes, research results show that MPSP process can obtain the best surface topography and roughness, micro-hardness, and residual stress field distribution; MPSP process has the longest fatigue life, and the fatigue life of MPSP process is about 68 times of M process, 56 times of MP process, and 48 times of MPS process; The fatigue fracture of the specimen after MPSP process is flat, and the depth of the crack initiation site for MPSP specimen is approximately 150μm below the surface.

Investigation on surface residual stress distribution and evaluation of engineering ceramics in rotary ultrasonic grinding machining

Residual stress of engineering ceramics is one of surface integrity evaluation indexes affecting the parts’ strength properties. Rotary ultrasonic grinding machining is the most powerful machining method for engineering ceramics with better surface integrity. The residual stress field distribution is changed due to micro cracks which are inevitable in the process. A residual stress distribution model of machined surface micro crack tip has been established in the paper. And the experimental results enable us to obtain surface residual stress distribution of engineering ceramics in rotary ultrasonic grinding machining. Then, we propose an evaluation parameter called confidence stress tolerance to evaluate surface residual stress characteristic. Preliminary results indicate that surface residual stress distribution is in line with the normal distribution. Confidence stress tolerance is an effective parameter to improve the evaluation reliability. Furthermore, precision and affecting factors of confidence stress tolerance evaluation have also been investigated.

Effect of high-pressure rolling followed by laser processing on mechanical properties, microstructure and residual stress distribution in multi-pass welds of 304L stainless steel

Multi-pass fusion welding by a filler material (wire) is normally carried out to join thick steel sections used in most engineering applications. Multiple thermal cycles from a multi-pass weld resulted in a variable distribution of residual stress field across the weld and through the thickness. Presence of tensile residual stresses can be detrimental to the integrity and the service behaviour of the welded joint. In addition to a complex distribution of residual stress state, multi-pass welds also form dendritic grain structure, which are repeatedly heated, resulting in segregation of alloying elements. In this research, microstructural refinement with modification of residual stress state was attempted by applying post-weld cold rolling followed by laser processing and then cold rolling. The residual stress was determined non-destructively by using neutron diffraction. Post-weld cold rolling followed by laser processing was carried out to induce recrystallization of the cold rolled grains. Microstructural characterisation indicates a significant grain refinement near the capping pass. However, post-weld cold rolling followed by laser processing reinstates the lock-in stress. In this study, it was demonstrated that a complete recrystallized microstructure with compressive state of stress can be formed when a further cold rolling is applied on the laser processed, recrystallized microstructure.

Research on residual stress in SiCfreinforced titanium matrix composites

This study aimed to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites. The analytical solution of residual stress field distribution was obtained by using coaxial cylinder model, and the numerical solution was obtained by using finite element model (FEM). Both of the above models were compared and the thermal residual stress was analyzed in the axial, hoop, radial direction. The results indicated that both the two models were feasible to theoretical calculate the thermal residual stress in continuous SiC fiber reinforced titanium matrix composites, because the deviations between the theoretical calculation results and the test results were less than 8%. In the titanium matrix composites, along with the increment of the SiC fiber volume fraction, the longitudinal property was improved, while the equivalent residual stress was not significantly changed, keeping the intensity around 600 MPa. There was a pronounced reduction of the radial residual stress in the titanium matrix composites when there was carbon coating on the surface of the SiC fiber, because carbon coating could effectively reduce the coefficient of thermal expansion mismatch between the fiber and the titanium matrix, meanwhile, the consumption of carbon coating could protect SiC fibers effectively, so as to ensure the high-performance of the composites. The support of design and optimization of composites was provided though theoretical calculation and analysis of residual stress.

Numerical modeling of residual stress induced by laser shock processing

Laser shock processing (LSP) is proving to be a competitive technology to traditional surface enhancement techniques in engineering products. The LSP develops a significant residual compressive stress deep into the surface of a metal alloy, which is beneficial for fatigue, wear and corrosion. In this paper, a comprehensive three-dimensional model is presented to predict the development, magnitude and distribution of residual stress field induced by LSP. In order to verify the FEA model, a benchmark simulation is performed verified with available experimental results. The predicted residual stress field for single laser shock processing is well correlated with experimental data. With the aid of the model, the influences of LSP parameters such as full width at half maximum (FWHM), power density, spot size, number of shots and overlapped shots have been analyzed. Some optimized parameters of LSP can be made by employing the presented models and results of the parametric investigations.

Distribution of residual stress fields in TC6 blade by LSP

The aim was to analyse distribution rule of residual stress fields in a TC6 titanium alloy blade with multiple impacts and different spot overlapping ratios by comparing the numerical simulation and laser shock processing (LSP) experiments results. A dynamic model based on the finite element method was presented to simulate multiple impacts and different spot overlapping ratios by single sided LSP with round laser spot, and the distribution rule of residual stress fields based on different process condition was described. Further, LSP experiments of multiple impacts and different spot overlapping ratios were executed to compare the simulation results by measuring and fractographic observation. The results indicated that simulated values were reasonable with experimental values, and the compressive residual stresses were greatly increased and driven deeper below the blade surface with multiple impacts and high spot overlapping ratios on the same spot.

Simulation of Induction Quenching on the Work Area of Reading Arm in Electronic Dobby Shedding Device

Reading arm is a key component of the high-speed looms, thin-walled parts, 3mm thick, easy to be deformation during heat treatment.The hardness HRC60 of workeded area is required and uniform distribution.Temperature field of induction hardening process and distribution of residual stress field were simulated by ANSYS software.The decarburization of induction hardening region was also simulated by Deform software. Heat treatment process was optimized by the simulated results.

Residual stress field induced by shot peening based on random-shots for 7075 aluminum alloy

High-strength 7075-T651 aluminum alloy was selected as the research object, and the random-shots FE model was developed; the influences of shots number and spatial location on residual stress field (RSF) were discussed; the influence of analysis step time (AST) on the stability of RSF was analyzed, and the influences of coverage rate and surface roughness of component on the distribution of RSF were investigated. The results indicate that the generated RSF is seriously affected by subsequent shots number and location; RSF tends to be stable when AST adds to 0.075 ms for 45 shots FE model, and the AST values of 15, 25, 65 and 85 shots FE model are 0.065, 0.0683, 0.0817 and 0.0883 ms respectively. For shot peening with different coverage rates, σsrs and σmcrs increase with the variation of shots number from 15 to 65, then decrease when shots number is 85, variation of Zm is not obvious, Z0 increases with the increment of shots number. For shot peening of component with different surface roughness Ra, variation of σsrs has no obvious regularity, and σmcrs, Zm and Z0 decrease with the increment of Ra.