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Nickel alloys are widely used in aerospace and defense industries due to their excellent high-temperature characteristics. In order to increase fatigue resistance and oxidation corrosion resistance, aerospace curved surface parts always need to be strengthened using laser shock peening technology on five-axis machines. However, it is easy to generate dense laser spots in certain regions during the process, which might lead to an uneven distribution of residual stress on surfaces of the component. To address this issue, the study investigates the problem of excessive spot overlap rate at large curvature positions caused by a mismatch between the surface curvature of curved components and the dynamic performance of equipment, then proposes an optimization algorithm for motion control based on linear interpolation principles. By analyzing the relationship between the feed rate of the program segment and the actual feed rate, the speed of each axis of the machine tool is confirmed and adjusted, and the control flow of the optimization algorithm is established. The feasibility of the algorithm is preliminarily verified by comparing the changing trend of feed rate before and after optimization through simulation. In actual laser shock peening experiments on nickel alloy spherical shell elements, the laser spot distribution on the surface of the component is uniform, and the relative error range between the actual overlap ratio and the theoretical value can be controlled within 5%, demonstrating the correctness of the optimization algorithm. This study can significantly improve the surface machining quality of curved components and have practical applications. [ABSTRACT FROM AUTHOR]

This article explores the use of deep learning, specifically artificial neural networks, to optimize the parameters of laser shock peening in the Ti-6Al-4V alloy. Laser shock peening is a technique that introduces compressive residual stresses to improve the fatigue properties of materials. The authors develop a neural network model that accurately predicts residual stresses and depth of the modified layer. The model can be used to identify optimal processing parameters for achieving maximum depth and compressive stresses. The study concludes that the neural network predictions align with experimental results. [Extracted from the article]

The high‐temperature fretting fatigue damage characteristics of dovetail specimens strengthened by nanosecond laser (NL) and nanosecond combined femtosecond laser (F‐NL) were investigated. The results show that the fretting fatigue life of the NL strengthened sample (NL sample) is improved by 211.2% compared to the base metal samples (BM sample). The lifetime of the nanosecond combined femtosecond strengthened sample (F‐NL sample) was increased by 319.6%. It was attributed to the strengthening introducing hardened layers, residual compressive stress field, and high density of dislocations. The combined strengthening process reduces the surface roughness of the NL strengthened surfaces, while the strengthening influence layer is further increased. The fracture morphology shows that the crack source of the strengthened specimen has changed from multi‐source sprouting to single‐source sprouting, and the crack source sprouted on the subsurface. The fatigue strip morphology similarly confirms that a reduction in the crack propagation rate occurs. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this paper is to study the effect of laser shock peening (LSP) on mechanical behaviour of the laser-directed energy deposition (LDED)-based printed 15-5 PH stainless steel with U and V notches. The study specifically concentrates on the evaluation of effect of scan strategy, machining and LSP processing on microstructural, texture evolution and fatigue behaviour of LDED-printed 15-5 PH steel. Design/methodology/approach: For LSP treatment, 15-5 PH steel was printed using LDED process with bidirectional scanning strategy (XX [θ = 0°) and XY [θ = 90°]) at optimised laser power of 600 W with a scanning speed of 300 mm/min and a powder feed rate of 3 g/min. Furthermore, LSP treatment was conducted on the V- and U-notched fatigue specimens extracted from LDED-built samples at laser energy of 3.5 J with a pulse width of 10 ns using laser spot diameter of 3 mm. Post to the LSP treatment, the surface roughness, fatigue life assessment and microstructural evolution analysis is performed. For this, different advanced characterisation techniques are used, such as scanning electron microscopy attached with electron backscatter diffraction for microstructure and texture, X-ray diffraction for residual stress (RS) and structure information, Vicker's hardness tester for microhardness and universal testing machine for low-cycle fatigue. Findings: It is observed that both scanning strategies during the LDED printing of 15-5 PH steel and laser peening have played significant role in fatigue life. Specimens with the XY printing strategy shows higher fatigue life as compared to XX with both U- and V-notched conditions. Furthermore, machining and LSP treatment led to a significant improvement of fatigue life for both scanning strategies with U and V notches. The extent of increase in fatigue life for both XX and XY scanning strategy with V notch is found to be higher than U notch after LSP treatment, though without LSP samples with U notch have a higher fatigue life. As fabricated sample is found to have the lowest fatigue life as compared to machines and laser peened with both scan strategies. Originality/value: This study presents an innovative method to improve the fatigue life of 15-5 PH stainless steel by changing the microstructure, texture and RS with the adoption of a suitable scanning strategy, machining and LSP treatment as post-processing. The combination of preferred microstructure and compressive RS in LDED-printed 15-5 PH stainless steel achieved with a synergy between microstructure and RS, which is responsible to improve the fatigue life. This can be adopted for the futuristic application of LDED-printed 15-5 PH stainless steel for different applications in aerospace and other industries. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is a formidable cold working surface treatment that provides high-energy precision to enhance the mechanical properties of materials. This paper delves into the intricacies of the LSP process, offering insights into its methodology and the simulation thereof through the finite element method. This review critically examines various points, such as laser energy, overlapping of shots, effect of LSP on residual stress, effect of LSP on grain refinement, and algorithms for simulation extrapolated from finite element analyses conducted by researchers, shedding light on the nuanced considerations integral to this technique. As the significance of LSP continues to grow, the collective findings underscore its potential as a transformative technology for fortifying materials against mechanical stress and improving their overall performance and longevity. The discourse encapsulates the evolving landscape of the LSP, emphasizing the pivotal role played by finite element analysis in advancing our understanding and application of this innovative surface treatment. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is a relatively novel and promising surface hardening method. An absorbing layer, which is needed to protect the specimen surface from undesirable thermal effects caused by laser irradiation, should be considered as one of many varying parameters. The physical characteristics of the coating and its adhesion to the specimen surface can significantly influence the result of LSP. In this study, three commonly used absorbing coatings, namely black polyvinylchloride tape with a sticky layer, aluminum foil, and black alkyd paint were used to cover three-millimeter-thick plates of the Ti-6Al-4V titanium alloy with globular or lamellar microstructures. LSP of one side of the plates was carried out with a power density of 10 GW/cm2. The hole drilling method was used to evaluate residual stresses. The aluminum foil was found to be the optimal option for LSP of the Ti-6Al-4V titanium alloy. Microstructural investigations carried out using EBSD analysis suggested that no significant reduction in grain size, twinning, or dislocation density growth occurred as a result of LSP irrespective of the initial structure. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the laser beam overlap rate on the mechanical properties of Al3003 aluminum alloy arc weldment with laser peening. To determine the optimal laser beam overlap rate for laser peening of the weldment, peening experiments were conducted on bead-welded and butt-welded specimens with varying overlap rates, and the effect of the beam overlap rate was analyzed. As the overlap rate increased, the residual stress changed from tensile to compressive, with the highest level of compressive residual stress at the overlap rate of 75%. Laser peening was performed on the aluminum weldment of the prototype, applying the optimal peening conditions identified earlier. As a result of comparing the residual stress, hardness, and tensile strength of the weld before and after laser peening, it was found that the tensile residual stress in the weldment was improved to a compressive residual stress of about −50 MPa or more. The hardness and tensile strength of the weld increased after peening, and the mechanical properties were also improved. [ABSTRACT FROM AUTHOR]

By means of microstructure observation and mechanical property tests, the influence of the laser pulse energy of the laser shock processing (LSP) on the surface residual stress, microstructure, microhardness and fatigue limits of the M50 steel was studied. Results show that when the laser pulse energy increases from 4, 6 to 8 J, the surface damage of the sample becomes more and more pronounced, which gradually changes from pits to long-strip ravines. LSP increases the hardness of the steel, the maximum hardness occurs on the impact surface, and the microhardness gradually decreases as the distance from the impact surface increases. When the laser pulse energy rises from 4 to 8 J, the maximum hardness of the surface increases from 741 to 845 HV1, which are 2.90 and 11.33% higher than the steel matrix respectively. The depth of the hardened layer of the samples produced by LSP is also deepened when the laser pulse energy increases. The hardened layer depth is approximately 0.3 mm when the laser pulse energy is 4 and 6 J, which reaches 0.5 mm when the laser pulse energy is 8 J. LSP generates residual compressive stresses of − 423, − 565 and − 809 MPa on the surface of the samples when the laser pulse energy are 4, 6 and 8 J respectively. The residual compressive stresses can inhibit the expansion of cracks, so that the steel is less prone to fracture, and thereby the fatigue limit of the steel is increased by 45.95% from 740 MPa of the sample without LSP to 1080 MPa after LSP with the laser pulse energy of 8 J. [ABSTRACT FROM AUTHOR]

The present study reports the effect of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of the shear cut surfaces of type 304L stainless steel. The LSP is carried out on as shear cut surface of SS 304L steel at a fixed laser power density of 3.53 GW cm−2 with multiple passes, i.e., double and triple. The preliminary investigation showed that as shear cut surfaces of SS 304L possess a very high tensile residual stresses of the order of 450-700 MPa and hardness 400 HK0.1. The LSP treatment with double and triple pass led to the generation of high compressive residual stress of the order of − 200, and − 250 MPa as compared to as cut shear surfaces. Microscopic analysis revealed that the shear cut surfaces, after double and triple LSP treatment exhibited significantly reduced susceptibility to the SCC in chloride environment after 8-hour test. The results of the present study recommend that LSP treatment can acts as protector of the product and components of austenitic stainless steel with sheared cut surfaces stored for long time in susceptible corrosive environment. This way a huge loss to the nuclear and process industries can be minimized. [ABSTRACT FROM AUTHOR]

Lightweight thin-walled parts are widely used in the aviation and aerospace industries, and with the further increase in the complexity of their features, the traditional manufacturing process can no longer fully meet the high requirements of industrial component manufacturing. In this work, thin-walled parts are processed by Laser based powder bed fusion of metals (PBF-LB/M), and the effects of process parameters on residual stress, hardness, mechanical properties and microstructure of thin-walled parts are systematically investigated. The simulation results show that the maximum equivalent residual stresses are distributed in the combination of the solid and the substrate, and the minimum equivalent residual stresses are mainly distributed in the top two ends and the middle part of the solid, and the stress distribution is symmetrical. In addition, the maximum equivalent residual stress increases with the increase of laser power, and decreases with the increase of scanning spacing or scanning speed. The experimental results show that with the increase of laser energy density, the tensile strength and yield strength of thin-walled parts show a tendency of increasing first and then decreasing. Finally, high-quality thin-walled parts were successfully fabricated by the optimized process parameters, and their tensile and yield strengths were increased by 6.1% and 15.9%, respectively. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is a technique similar to shot peening that improves the mechanical properties, such as fatigue performance of metallic structures, by introducing compressive residual stresses. This study aims to present a 3D finite element simulation for simulating residual stress field after laser shock peening without absorbent coating (LSPwC) in real applications. Also, the residual stress distribution induced by LSPwC in a Rene 80 Ni-based superalloy was obtained via X-ray diffraction and hole drilling measurements. The excellent correlation between the simulated residual stress values and experimental test results proved this model reliable. Laser peening Rene-80 superalloy samples with single LSP impact at a laser power density of 6 GW/cm2 led to a significant increase in the compressive residual stress (-405 MPa) compared to the unpeened sample. The yield strength of laser-peened samples was improved by ~ 16% and a reduction of ~ 12% in the failure strain compared to the baseline sample. Similarly, the laser peening increased microhardness by 26% compared to the untreated samples. Scanning electron microscopy (SEM) was also utilized to interpret the failure mechanism of samples examined before and after LSP. [ABSTRACT FROM AUTHOR]

Low-plasticity burnishing (LPB) is usually used for finishing of material to enhance service performance by improving the roughness and inducing compressive residual stress to surface and underneath layers. However, processing of nickel-based superalloys by burnishing is usually challenging because of resistance of material against plastic deformation. Therefore, the material should be burnished following multiple pass that results increase of production time. In the present work, a plausible solution, namely electric-current-assisted burnishing (ECAB), is introduced to be used as post-treatment for Inconel 718 material produced by laser powder bed fusion process. The surface integrity aspects, i.e., roughness, hardness, residual stress, microstructure change and fatigue life after LPB and ECAB under different pass number, were compared by as-built material to identify the efficiency of the introduced methodology. The results indicated that for conventionally burnished sample, after second pass, no more improvement in fatigue life of the sample is observed and even it decreases at third pass. On the other hand, it was found that for the ECABed samples, after only a single pass, the fatigue life and surface integrity aspects reach maximum values of conventionally burnished sample implying ECAB causes reduction of production time to one third. Moreover, it was found that in contrast to conventional burnishing process, in ECAB process, due to electroplasticity effect, contribution of pass number in improvement of fatigue life and surface integrity will be more substantial where continuous enhancement is seen up to three pass. Current is applied to the process, the pass number is more influential fatigue life and surface integrity aspects are. [ABSTRACT FROM AUTHOR]

To investigate the effects of laser peening (LP) on the surface and bending fatigue properties of carburized steel (JIS SCM420), surface roughness measurements, residual stress measurements, retained austenite measurements, and four-point bending fatigue tests were conducted. After LP, the compressive residual stress was applied on the surface, with the effect extending to a depth of more than 1 mm. Due to the high compressive residual stress, the bending fatigue strength of LP specimen was 1.46 times higher than that of the gas carburized specimen even though the surface roughness was increased by LP. Notably, the amount of retained austenite was 10.9% at the outermost surface of LP specimen, and high-density twins were observed in the lath martensite structure. This can be attributed to high strain rate deformation by LP. [ABSTRACT FROM AUTHOR]

In order to investigate the laws of the laser peening forming process and the effects of laser peening on the surface quality and tensile properties of 5083 aluminum alloy, experiments were conducted utilizing various laser peening paths, energies, and plate thicknesses. Subsequently, laser peening forming experiments were performed on S-shaped and different shapes of aluminum alloy substrates. The impact of different laser peening durations on surface morphology and tensile properties was then analyzed. Results indicated that the largest bending deformation perpendicular to the laser peening path reached 12.5 mm. In cases where the laser peening path was inclined relative to the horizontal direction, torsional deformations were observed in the aluminum alloy plate. For laser energy levels of 5 J, 6 J, and 7 J, deformation amounts were 3.8 mm, 4.9 mm, and 5.4 mm, respectively. Plates with thicknesses of 4 mm exhibited convex deformation, while those with 2 mm thickness showed concave deformation. Furthermore, following one and two laser peening cycles, the residual stresses in the alloy plates were −80 MPa and −107 MPa, the surface hardness increased by 16 HV and 31 HV, the roughness increased by 2.495 μm and 3.615 μm, and the tensile strength increased by 9.5 MPa and 18.5 MPa, respectively. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is a powerful technique for improving the fatigue performance of metallic components by customizing compressive residual stresses in the desired near-surface regions. In this study, the residual stress distribution characteristics of 6061-T6 aluminum alloy induced by LSP were identified by the X-ray diffraction method, and their dependent factors (i.e., LSP coverage, LSP energy, and scanning path) were evaluated quantitatively by numerical simulations, exploring the formation mechanism of LSP residual stresses and the key role factor of the distribution characteristics. The results show that LSP is capable of creating anisotropic compressive residual stresses on the specimen surface without visible deformation. Compressive residual stresses are positively correlated with LSP coverage. The greater the coverage, the higher the residual stress, but the longer the scanning time required. Raising LSP energy contributes to compressive residual stresses, but excessive energy may lead to a reduction in the surface compressive residual stress. More importantly, the anisotropy of residual stresses was thoroughly explored, identifying the scanning path as the key to causing the anisotropy. The present work provides scientific guidance for efficiently tailoring LSP-induced compressive residual stresses to improve component fatigue life. [ABSTRACT FROM AUTHOR]

With the development of laser deposition technology, the Invar alloy matrix materials is a kind of potential laser deposited coating because of low expansion coefficient, which is favor to decrease the residual stress in the coating and get the crack-free coating. But the poor tribology properties of the pure Invar alloy limit the application of invar alloy matrix coating. In this work, the enhanced tribology properties induced by eutectic microstructure strengthening and in-situ reinforce in composite coating is obtained by adjusting the Ti/B ratio in the composites. Furthermore, the dependence of the eutectic microstructure and in-situ reinforcement on the tribology properties is discussed. As the Ti/B ratio increased, the content of the primary γ-Fe phase gradually rises, the content of γ-Fe/Ni2B eutectic microstructure decreases in matrix, and the volume fraction of in-situ TiB2 particles progressively increase. With an increased Ti/B ratio, the hardness of the coating has a peak value, but the friction coefficient and wear volume have a minimum value at same time. When eutectic microstructure strengthening and in-situ reinforcing coexist in composite coating, the good tribology properties can be obtained. This work provides a new approach for obtaining new materials with good tribology properties by the use of eutectic strengthening and in-situ reinforcing. [ABSTRACT FROM AUTHOR]

In view of the difficulties such as coarse microstructure, performance degradation and excessive residual stress during the preparation of Ti-6Al-4V layers by laser cladding, the microstructure and mechanical properties of such a Ti-6Al-4V coating were optimized and improved based on the plastic deformation effect caused by laser shock peening (LSP). The characteristics of phase composition, changes in microstructure and morphology, grain plastic deformation and the influence of mechanical properties of the laser clad Ti-6Al-4V coating were studied pre- and post-LSP. The results indicate that the α/α' phase content increases and the β phase content decreases after LSP. The β phase and acicular martensite α' phase is refined significantly and divided, and the basket structure presents a more dense and staggered distribution after LSP. Laser cladding causes the grains in the Ti-6Al-4V coating to undergo plastic strain and the degree of grain refinement was significantly improved following LSP. The microhardness at the top of the laser clad Ti-6Al-4V coating increases from 23 to 30% compared after LSP. At the same time, the LSP promotes the transformation of residual tensile stress to compressive stress on the surface of the laser clad Ti-6Al-4V coating, with an average residual compressive stress value of about 339 MPa. This study provides theoretical and methodological references for optimizing the microstructure and properties of Ti-6Al-4V coatings. [ABSTRACT FROM AUTHOR]

This study, based on the Simufact Welding analysis software, established a three-dimensional finite element computational model according to actual welding conditions. Using a combined volumetric heat source, we analyzed the magnitude and distribution of residual stress after laser arc composite welding of dissimilar aluminum alloys, and validated the results with experimental data. The influence of different preheating temperatures on the variation rule of residual stress in each part of the weldment was explored. The results showed that the calibration results of the combined volumetric heat source model were ideal, and that the simulation results of transverse and longitudinal residual stress were in good agreement with the actual results. The average residual stress in the heat-affected zone (HAZ) of the 5083-H112 aluminum alloy was about 190 MPa, which is close to the yield strength of the base metal at room temperature (193 MPa); the average residual stress at the weld seam was about 230 MPa; and the average residual stress in the HAZ of the 6063-T6 aluminum alloy was about 80 MPa. In addition, preheating before welding has a positive effect on reducing residual stress after welding. The optimal preheating temperature for the 5083-H112 aluminum alloy is about 170°C, and for 6063-T6 aluminum alloy it is about 220°C. [ABSTRACT FROM AUTHOR]

The influence of laser-alloyed stainless steel coatings on the properties of the surfaces of cast iron discs, such as friction-induced vibration and noise, friction coefficient, residual stress, hardness, and corrosion resistance, was investigated in this study. The experimental results show that after laser alloying, the surface hardness of the cast iron discs increased significantly. The residual stresses on the surfaces of the laser-alloyed discs changed from tensile to compressive residual stresses, while any compressive residual stresses increased by more than six times. Most of the laser-alloyed discs demonstrated better performance in friction-induced vibration and noise damping and friction reduction. Metallographic observation and XRD (X-ray diffraction) analysis results show that the laser-alloyed layer is mainly a mixture of acicular martensite and dendritic material, while the phase composition of laser-treated discs is mainly martensitic, [Fe, Ni], Fe3Si, Cr23C6, and austenite, which plays a significant role in the improvement of the properties of the laser-alloyed cast iron in physics, tribology and corrosion resistance. This research has significance for the laser surface treatment of various cast irons and steels, which is an increasingly important manufacturing technology in the vehicle friction brake industry. [ABSTRACT FROM AUTHOR]

The manufacture of damping alloy parts with stable damping properties and high mechanical performances in the selective laser melting (SLM) process is influenced by temperature evolution and residual stress distribution. Choosing an appropriate scanning strategy, namely the specific trajectory along which the laser head scans powders within given area, is crucial, but clearly defined criteria for scanning strategy design are lacking. In this study, a three-dimensional finite element model (FEM) of the SLM process for manufacturing a WE43 alloy component was established and validated against the published experimental data. Eleven different scanning strategies were designed and simulated, considering variables such as scanning track length, direction, Out–In or In–Out strategy, start point, and interlayer variation. The results showed that scanning strategy, geometry, and layer number collectively affect temperature, melt pool, and stress outputs. For instance, starting scanning at a colder part of the powder layer could lead to a high peak temperature and low melt pool depth. A higher layer number generally results in lower cooling rate, a lower temperature gradient, a longer melt pool life, and larger melt pool dimensions. Changing the start point between scanning circulations helps mitigate detrimental residual stress. This work highlights the potential of analyzing various scanning strategy-related variables, which contributes to reducing trial-and-error tests and selecting optimal scanning strategies under different product quality requirements. This article can assist in the design of appropriate scanning strategies to prevent defects such as element loss due to evaporation, poor bonding, and deformation or cracking from high residual stress. Additionally, identifying stress concentration locations and understanding the effects of geometry and layer number on thermal and mechanical behaviors can assist in geometry design. [ABSTRACT FROM AUTHOR]

Aluminum alloy plates are widely used to manufacture large-scale integral structure parts in the field of aerospace. During the forming and processing of aluminum alloy plates, different degrees of residual stress are inevitably produced. Fast and accurate detection of residual stress is very essential to ensuring the quality of these plates. In this work, the longitudinal critically refracted (LCR) wave detection method based on a one-transmitter and double-receiver (OTDR) transducer and the finite element simulation were employed to obtain the residual stress. Aluminum alloy plates with different deformation amounts were fabricated by rotary forging to obtain different residual stress states. Results reveal that the plate formed by rotary forging is in a stress state of central tension and edge compression. As the deformation increases from 20% to 60%, the peak residual tensile stress increases from 156 MPa to 262 MPa, and there is no significant difference in the peak compressive stress. When the deformation reaches 60%, the difference in the residual stresses at different depths is less than 13%, which indicates that the plastic deformation zone basically penetrates the entire longitudinal cross-section of the plate. The maximum deviation between measurement and FE is 61 MPa, which means the experimental data are in good agreement with the FE results. [ABSTRACT FROM AUTHOR]

In the present study, the effect of laser intensity on the microstructure, residual stress, microhardness, and corrosion resistance property of laser shock peened Ti6Al4V using an Nd: YAG laser has been investigated. The applied laser intensity varied from 1 to 8 GW/cm2. During the processing, the pulse density was 574 pulses/cm2, and water was used as a confining layer. Due to laser shock peening, there is refinement of microstructure and presence of oxides on the surface. The residual stress on the surface was found to vary from + 130.12 to − 138.16 MPa and varied with process parameters. There is an increase in microhardness which also varied with process parameters. Due to laser surface processing, there is a significant improvement in corrosion resistance. A detailed structure–property correlation has been established. [ABSTRACT FROM AUTHOR]

Residual stress and plastic strain in additive manufactured materials can exhibit significant microscopic variation at the powder scale, profoundly influencing the overall properties of printed components. This variation depends on processing parameters and stems from multiple factors, including differences in powder bed morphology, non-uniform thermo-structural profiles, and inter-layer fusion. In this research, we propose a powder-resolved multilayer multiphysics simulation scheme tailored for porous materials through the process of selective laser sintering. This approach seamlessly integrates finite element method (FEM) based non-isothermal phase-field simulation with thermo-elasto-plastic simulation, incorporating temperature- and phase-dependent material properties. The outcome of this investigation includes a detailed depiction of the mesoscopic evolution of stress and plastic strain within a transient thermo-structure, evaluated across a spectrum of beam power and scan speed parameters. Simulation results further reveal the underlying mechanisms. For instance, stress concentration primarily occurs at the necking region of partially melted particles and the junctions between different layers, resulting in the accumulation of plastic strain and residual stress, ultimately leading to structural distortion in the materials. Based on the simulation data, phenomenological relation regarding porosity/densification control by the beam energy input was examined along with the comparison to experimental results. Regression models were also proposed to describe the dependency of the residual stress and the plastic strain on the beam energy input. [ABSTRACT FROM AUTHOR]

The service performance of hot stamped ultra-high strength steel after die punching was evaluated in this paper through typical experiments, including tensile tests, bending tests, and hydrogen embrittlement tests, as well as characterization analysis. The tested samples were prepared through a specially designed tool by considering different die clearances, punch corner radii, and punch shapes. The results showed that the tensile properties are closely related with the selected punching parameters, while the bending properties and hydrogen embrittlement susceptibility are less sensitive to parameters. Furthermore, the laser cutting method was also involved to produce holes on hot stamped parts and compared with the punching samples. It was found that the laser cutting samples performed better in terms of tensile properties and hydrogen embrittlement susceptibility, which were due to the effects of annealing treatment during laser cutting that decreases the material hardness and brings compressive residual stress near the cutting surface, while the bending properties are insensitive to different drilling methods. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has shown advantages to fabricate complex components in an efficient way. However, it has some limitations related to imperfections on the as-built parts that may limit its mechanical behavior and performance. The aim of this paper is to investigate the effect of laser shock peening (LSP) as a post-processing technique of components produced by AM. Porosity, microstructure, residual stresses, and fatigue life of Inconel 718 samples manufactured by laser powder bed fusion (LPBF) and then treated by LSP have been evaluated. For the laser shock peening (LSP) treatment, a Nd:YAG pulsed laser operating at 10 Hz with 1064 nm of wavelength was used; pulse density was 2500 pulses/cm2. The LSP setup was the waterjet arrangement without protective coating. Residual stress distribution as a function of depth was determined by the hole-drilling method. Fatigue specimens were LSP treated on both sides and then cyclic loading was applied with R = 0.1. Residual stress profiles of as-built specimens showed tensile residual stresses while specimens with LSP exhibited compressive residual stresses. Fatigue life in specimens with stress relief heat treatment plus LSP showed an increase of 18–22% with respect to that of as-built specimens. Porosity levels were lower than 1% in the tested specimens, while surface microhardness increased due to LSP. It is shown that LSP is a viable alternative to improve the performance of IN718 components processed with AM. [ABSTRACT FROM AUTHOR]

Small-hole structures, such as the millions of fastener holes found on aircraft, are typical stress-concentration structures prone to fatigue failure. To further improve the strengthening process of this small-hole structure, we make up for the limitations of laser shock processing (LSP) of small holes by combining it with the ultrasonic extrusion strengthening (UES) process to form a new strengthening method—laser shock and ultrasonic extrusion strengthening (LUE). The influence of the LUE process sequence and process parameters on residual stress distribution was studied through FEM, and the gain of fatigue life of specimens after LUE strengthening was also explored through tests. The results show that when using LUE technology, the friction force decreases with the increase in amplitude and decreases by 3.2% when the amplitude is maximum. The LUE process eliminates the thickness effect generated by LSP, which can achieve good stress distribution of small-hole components under smaller laser shock peak pressure, and reduces equipment power. LUE can significantly improve the fatigue life of small-hole components, and the maximum fatigue life gain can be up to 310.66%. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion is a promising technique that can produce complex-shaped and integrated part. However, distortion and residual stress are two issues that may decrease the precision and performance of built parts. Classical thermal gradient mechanism offers a basic interpretation toward distortion and residual stress. The evolutions of distortion and residual stress in laser powder bed fusion remain unclear. In this study, we used a physical model with an assumption of constraining force to illustrate the evolutions of distortion and residual stress during the additive process. Based on the model, we are able to understand the phenomenon of X-directional shrinkage, Z-directional distortion, and "tensile-compressive-tensile" distribution of X-directional stresses at the same time. It can be concluded that the shrinkage, distortion, and X-directional residual stress all result from the constraint between previously deposited layer and newly deposited layer, which has a strong shrinkage tendency when cooling. The distortion of part increases with deposition height, especially during first several layers. The "tensile-compressive-tensile" distribution of X-directional stresses can be maintained during the additive process. The magnitude of top tensile stress remains stable, while the tensile stress at bottom increases with the deposition height. This work provides a comprehensive understanding toward the evolutions of distortion and residual stress in laser powder bed fusion. [ABSTRACT FROM AUTHOR]

The role of the initial residual stresses (IRS) induced by the milling on the efficacy of laser shock peening (LSP) was investigated numerically on IN718 specimens. Three milling conditions exhibiting high (3.5 μm), medium (1.1 μm), and low (0.6 μm) surface roughness were considered for LSP. Experimentally measured (from XRD) milling-induced sub-surface (up to 60 μm depth) residual stresses were introduced into the simulations of LSP as predefined fields. The role of spot diameter with the IRS on the LSP-induced residual stress was studied systematically. For most cases, the tensile IRS from milling caused a significant decrease in the magnitude of maximum compressive residual stresses induced by LSP. [ABSTRACT FROM AUTHOR]

Due to the high manufacturing cost, the failure or wear of FGH4096 superalloy parts can be quickly repaired through laser melting deposition (LMD). However, the repeated local rapid heating and cooling processes can increase residual stresses (RS), which reduce the service life of remanufactured parts and even cause cracking. This study analyzed the microstructure and formability of FGH4096 under different laser energy densities and scanning strategies and investigated the RS along the height direction through x-ray diffraction. The results showed that the process parameters had no effect on the phases in the deposited layer, and relatively higher energy density was conducive to obtaining denser samples, while the scanning strategies had little effect on the relative density of the samples. The RS at the top of the cladding layer exhibited tensile stress, while it exhibited compressive stress at the bottom or heat-affected zone. The maximum stress values were related to the process parameters, and lower energy density and an inclined scanning strategy were conducive to reducing the maximum RS and increasing the thickness of the low-stress layer. The research can help design or optimize LMD process parameters for FGH4096 to maximize the relative density of cladding layers while minimizing RS. [ABSTRACT FROM AUTHOR]

Laser beam powder bed fusion (LB-PBF) is an edge additive manufacturing technology that allows complex near-net shape components to be produced. The freedom of design of the LB-PBF process makes it possible to produce optimized geometries, driving the application of this process in sectors in which high performance is fundamental such as aerospace and automotive. However, the building process inherently generates residual stresses in the part and the use of support structures become essential to anchor the part to the building platform and avoid problems in the downfacing surfaces that may warp or collapse during the production process. In this paper, different support densities obtained using different geometries of support structures are investigated to evaluate how they affect the residual stress distribution in the supported part. Two families of support structures were considered, linear-type and volumetric-type, including also a hybrid support structure that combined a massive volume topped by a linear support structure. Results highlighted that the combined choice of support density and geometry influences the magnitude and the distribution of sub-superficial residual stresses near the support-part interface and that appropriate design is essential to prevent excessive distortion or failure. [ABSTRACT FROM AUTHOR]

Mg5Zn0.2Ca is a promising alloy for medical tools owing to its excellent biocompatibility and biodegradability. This study presents the impact of surface mechanical attrition treatment (SMAT) parameters, explicitly colliding balls velocity (1, 5, and 10 m/s), and surface coverages (500, 1000, and 2000%), on the microstructure, hardness, and residual stress. SMAT forms a layer with a gradient in hardness, crystallite size, and twins. The surface hardness, which ranges between 68 and 118 HV0.05, increases with increased ball velocity and surface coverage. High ball velocity (10 m/s) and surface coverage (2000%) induce high compressive residual stress of about −175.5 MPa at ~600 µm depth. The specimens SMATed with a ball velocity of 5 m/s exhibit the higher surface compressive residual stress for all surface coverages. The maximum compressive residual stress of about −153.5 MPa is observed at the surface for the specimens SMATed at 5 m/s ball velocity and 500% coverage. The overall analysis reveals that the specimen treated at 10 m/s ball velocity and 2000% surface coverage exhibits the most refined grain structure, finely and densely distributed twins, maximum SMAT-induced thickness (~3000 µm), highest surface hardness (~2.1 times the non-SMATed specimen's hardness), and maximum compressive residual stress. [ABSTRACT FROM AUTHOR]

Surface integrity parameters are the major aspect in the extension of the fatigue life of aero- engine components. In this study, a modified burnishing surface treatment (low plasticity burnishing) with reduced cold work was proposed to improve surface integrity characteristics such as surface finish and hardness, and to induce stable, advantageous compressive residual stress in a cylindrical Ti-6Al-4 V specimen (as-received). In this process, a rolling rigid spherical tungsten carbide ball is pressed across a Ti-6Al-4 V specimen at an appropriate fluid pressure generated by the hydraulic unit. The low plasticity ball burnishing tooling system supported by a hydraulic unit of capacity 30 MPa is designed and developed in this study. By using a suitable specimen holding fixture, the ball burnishing with a small amount of plastic strain was carried out on the Ti-6Al-4 V cylindrical specimen. This research examined the effect of burnishing process variables namely tool pass and burnishing fluid pressure on compressive residual stresses, surface roughness, and hardness in Ti-6Al-4 V. The explicit dynamic analysis was carried out by using FE-Analysis software ABAQUS 6.17 as a part of numerical simulation. Hydraulic burnishing pressure and burnishing passes are the most influential parameters in generating favourable compressive residual stress, qualitative surface finish with less cold work in Ti-6Al-4 V turned specimen. [ABSTRACT FROM AUTHOR]

This article discusses a method for estimating residual stresses in metal samples produced by additive manufacturing, specifically focusing on steel cylindrical bars produced by laser powder bed fusion (LPBF). The method involves making a partial longitudinal cut in the bar using electrical discharge machining (EDM) and measuring the resulting deflection to assess the contribution of residual stresses. The study combines experimental analysis with numerical simulation using finite element modeling (FEM). The proposed method allows for the estimation of residual stresses in the laboratory without the need for special equipment. The article also provides a list of references that cover various topics related to residual stresses and mechanical properties of additively manufactured stainless steel, which can be useful for further research. [Extracted from the article]

Stress corrosion cracking (SCC) failures of austenitic stainless steel (ASS)-based dry storage canister (DSC) weld joints are a potential safety hazard in nuclear applications. The present study aims to provide deeper insights into the effect of novel laser shock surface patterning (LSSP) on the SCC resistance of DSC weld joints. The LSSP experiments were performed with varying intensity, covering the fusion zone (FZ), heat-affected zone (HAZ), and base material (BM). The SCC testing was conducted in boiling MgCl2 on U-bend specimens. The laser-induced shock wave developed during LSSP simultaneously caused strengthening and patterning effects by forming an array of micro-indentations. LSSP leads to austenitic to strain-induced martensitic (α′-phase) transformation, residual compressive stress (RCS), and grain refinement. In addition, surface hardness was improved, and surface roughness and volume fraction of α′-phase reduced significantly. The SCC testing on LSSP'ed U-bend specimens revealed enhanced SCC resistance compared to the unpeened U bends, which can be attributed to the presence of RCS in the subsurface and the minimal effect of surface roughness and volume fraction of α′-phase. [ABSTRACT FROM AUTHOR]

In this work, the possibility of employing shot peening and laser peening as pre‐treatments to a tartaric–sulfuric anodizing process on the fatigue behavior of 7050‐T7451 aluminum alloy components was investigated. The surface modifications and stress fields induced by the combination of the peening and anodizing processes were evaluated by scanning electron microscopy and residual stress assessment methodologies based on diffraction techniques, respectively. It was found that the anodizing process alone results in a significant reduction in fatigue life compared to the as‐machined condition especially in the high‐cycle fatigue (HCF) region of the S–N diagrams due to the presence of defects within the anodic layer that act as stress concentrators facilitating the initiation of fatigue cracks. The application of both shot and laser peening treatments is demonstrated to offset the negative effects induced by anodizing, offering greater safety margins useful for the design of critical aeronautical structures. Highlights: The possibility to employ peening processes as pre‐treatments to anodizing was studied.No significant influence of anodizing on residual surface stresses was observed.SP and LP provide significant benefits in the fatigue behavior of anodized components.Thicker anodic layers result in greater susceptibility to fatigue crack nucleation. [ABSTRACT FROM AUTHOR]

Aluminum alloy 6082-T6 is an important material for manufacturing the outer skin of high-speed trains, and laser shock forming can realize the rapid forming of complex-shaped plates. In order to improve the efficiency of the simulation modeling of laser shock forming for aluminum alloy 6082-T6, Python scripting language was used for the secondary development of Abaqus. A plugin was utilized to simulate and analyze the laser shock forming process of aluminum alloy 6082-T6. The coordinates of the plate after laser impact molding were measured using a coordinate measuring machine to calculate the arc bow height of the plate. The accuracy of the simulation model was verified by comparing with the simulation results. The deformation characteristics of plastic strain and arc height of aluminum alloy 6082-T6 under different laser process parameters were analyzed. The simulation plugin has a concise interface, high operability, and accurate results with the other parameters unchanged. When the laser energy is 5 J, 6 J, and 7 J, the corresponding arc heights are 5.9 mm, 6.6 mm, and 7.2 mm, respectively. As the thickness of the sheet increases, the deformation changes from concave at 1 mm to convex at 2 mm, 3 mm, 4 mm, and 5 mm. As the spot size increases from 1 mm to 5 mm, the transmission mode of the shock wave gradually changes from spherical wave to planar wave, and the arc height of the sheet increases from 4.6 mm to 8.2 mm. With the increase in the spot overlap rate, the impact area accumulates residual stress, and the arc height of the sheet is 5.7 mm, 6.6 mm, 7.3 mm, and 8.5 mm, respectively. The secondary development of ABAQUS 2021 using Python 3.6 scripting language has improved the efficiency of simulation modeling and provided reference for rapidly predicting the deformation characteristics of aluminum alloy 6082-T6 under different laser process parameters. [ABSTRACT FROM AUTHOR]

Adjustable Ring Mode (ARM) laser technology combined with Beam Oscillation optics module was introduced to effectively enhance weld quality in joining aluminium alloys. This study developed a three-dimensional (3-D) thermo-mechanical finite element (FE) model to analyze the distribution of thermally induced residual stresses in laser-welded 3003 aluminium alloy. The accuracy of model was validated through comparisons with experimental weld cross-sections and further reinforced by X-ray diffraction residual stress measurements. The transient temperature field and stress distribution during the welding process were investigated using the verified model. Additionally, the hardness and microstructure of the welded samples were examined through micro-hardness tests and scanning electron microscopy. Results showed that welding with beam oscillation resulted in less penetration but higher hardness and finer columnar grain size in the fusion zone. Additionally, the influence of varying standoff distances between two sequential weld beads on residual stress distribution was investigated. Numerical findings revealed that higher residual stress concentrations were located at the weld seam and dominated by tensile longitudinal residual stress and compressive transverse residual stress. As the distance between weld beads increased, transverse and equivalent residual stresses decreased, while longitudinal residual stress away from the bead increased. [ABSTRACT FROM AUTHOR]

To select the optimal treatment mode of Ti64 alloy specimens with a stress concentrator, several laser shock peening (LSP) modes are studied. The effectiveness of the modes was determined by two criteria: indirect, based on the residual stress (RS) profile formed immediately after LSP (the depth of the layer with compressive RS and its maximum value), and direct, based on the number of cycles to failure during fatigue testing of Ti64 alloy flat specimens after hardening by LSP. The most effective LSP mode, which improves the fatigue properties of the specimens with the concentrator of the studied geometry, has been determined. To study the physical RS generation mechanisms, structural studies of the specimens after LSP have been carried out using the Electron Backscatter Diffraction (EBSD) method. The obtained data include the spread of the grain orientation, the average grain misorientation, and the change in the number of defects in the grains under different LSP modes. The results of the microstructure studies correlate with the profiles of the residual stresses caused by LSP. [ABSTRACT FROM AUTHOR]

We consider the effect of laser shock peening without coating (LSPwC) on the structure and stress state of the AMg6 Aluminum alloy with a thickness from 4 to 14 mm before and after preliminary thermal annealing. The roughness parameters Ra and Rz after LSPwC are determined. The magnitude, depth, and profile of compressive residual stresses (CRS) are found to depend on the thickness of the material and preliminary heat treatment. The layer-by-layer X-ray diffraction analysis shows a correlation between the parameters of the crystal structure and the profile of residual stresses for the processed samples. We find homological distortions of the crystal lattice in the CRS zone and observe the formation of significant (up to - 100 MPa) residual stresses on the unprocessed side of the samples. Also, we determine the surface CRS magnitudes for double unilateral and bilateral processing. [ABSTRACT FROM AUTHOR]

Railway wheels are usually attached to axles by press-fitting; therefore, the mechanical processes taking place during operation can result in failure, with fatal consequences for the axle seats. This manuscript describes the effect of laser hardening on the residual stress state, microstructural parameters (lattice defects—dislocations, crystallites, microstrains, etc.), and mechanical properties of laser-hardened EA1N steel railway axles under fatigue life conditions. Differences were found between ground, single-track, and multi-track hardened surfaces. Tensile residual stresses, low dislocation densities and hardnesses, and different microstructures (tempered cubic martensite) were found at the overlapped tracks and at the boundary of the heat-affected zone and bulk surface compared with the hardened zone. As a result, the surface treatment of axle seats by laser hardening improved the fatigue failure resistance compared with untreated seats. Optimal properties of the integrity of the axle seat surface were achieved, including fatigue resistance, which seems to be positively influenced mainly by sufficient hardness and the appropriate microstructure. The influence of the other investigated parameters was not evident, and was reduced by the presence of fretting corrosion and press-fitting. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) increases fatigue strength and life while reducing crack propagation by creating compressive residual stress on the material's surface. The shock pressure generated by the laser and the target material surface is directly proportional to the laser power density. As the peak pressure induced by the laser pulse exceeds a threshold, a drop in compressive residual stress at the center of the round spot known as a "residual stress hole" is observed due to reverse plastic deformation. In the present paper, a numerical investigation is carried out to speculate the array type LSP (ALSP) with round spots for compressive residual stress generation. 3-D explicit numerical simulations with non-reflecting boundaries have been employed to study the influence of ALSP on the residual stress hole generation and compare it to the residual stress field induced by conventional LSP. The investigation included 1-D and 2-D arrays with different gaps between the spots and spot sizes. It is found that, with proper parameter selection, including the gap between spots, array dimension, and spot size, ALSP has the potential to reduce residual stress hole generation. The influence of ALSP with a large impact radius (R = 1 mm) is limited to no gap cases, but more pronounced for different array configurations with a small impact radius (R = 0.25 mm) ALSP. [ABSTRACT FROM AUTHOR]

JIS SUJ2 steel is most widely used in bearing steel. The advantages are good hardenability, excellent fatigue, wear resistance and comprehensive mechanical properties. The wear resistance and fatigue resistance of this steel are attracting more attention, and the residual stress state and its distribution on the surface of the heat affected zone are critical factors affecting the fatigue life and wear resistance of the parts. In this study, SUJ2 is used as a material by which to study the surface residual stress and retained austenite distribution of induction-hardened steel. Quenching and tempering treatments were used to obtain different microstructures and an induction method was used to re-quench the case region. After the heat treatment, the residual stress and retained austenite volume on the surface were analyzed by X-ray diffraction and analyses of the microstructure and the hardness were also conducted. The results show that the microstructure after heat treatment contains unsolved carbides, tempered martensite and retained austenite. In the induction-hardened area, the residual stress is all compressive, and the values are more than −750 MPa. In conclusion, the microstructures of the specimens before induction hardening have a significant impact on the effective case depth for the same output power condition and the surface residual stress changes from a tensile to a compressive state. In the induction-hardened area, the maximum of the residual compressive stress was increased as the austenitized temperature of quenching increased. [ABSTRACT FROM AUTHOR]

Residual stresses pose significant challenges in the powder bed fusion of metals using a laser (PBF-LB/M), impacting both the dimensional accuracy and mechanical properties. This study quantitatively analyzes deformation and residual stresses in additively manufactured Inconel 625. Investigating both as-built and stress-relieved states with varied scanning strategies (90°, 67°, strip, and 90° chessboard) in PBF-LB/M/IN625, distortion is evaluated using the bridge curvature method. Quantitative measurements are obtained through 3D laser surface scanning on pairs of bridge specimens—one measured before and after detachment from the build plate, and the other undergoing stress-relieving heat treatment at 870 °C for 1 h. The findings reveal that, among as-built specimens, the 90° and 90° strip strategies induce the least distortion, followed by the 67° and chessboard 90° strategies. Furthermore, stress-relief treatment significantly reduces residual stress levels. After post-treatment, the deformation in X-axis samples with 90° and 90° strip strategies decreases by 39% and 42%. In contrast, the samples with the 67° and 90° checkerboard strategies exhibit more pronounced reductions of 44% and 63%, respectively. These quantitative results contribute useful insights for optimizing PBF-LB/M/IN625 processes in additive manufacturing. [ABSTRACT FROM AUTHOR]

To investigate the effect of laser shock peening (LSP) on the fatigue crack propagation behavior of 316L stainless steel fabricated by directed energy deposition (DED), three‐dimensional finite element models of DED and compact tensile specimens before and after LSP are developed. The residual stress fields induced by DED and LSP are simulated, as well as the effects of different residual stresses on the stress intensity factor and effective stress ratio based on the contour integral method are also analyzed. The microstructure of the LSP region is observed by scanning electron microscope. When the crack length increases from 12 to 22.5 mm, the average effective stress ratio of the DED specimen is 0.133, and the average effective stress ratio of the DED specimen after LSP decreases to 0.110, which decreases by 17.3%. The fatigue lives of the DED specimen before and after LSP are 62.7% and 105.2% of that of the hot‐rolled plate. After LSP treatment, the fatigue life of the DED specimen is increased by about 1.68 times. The fracture morphology in the transient fracture zone changes from ductile and brittle mixed fracture to ductile fracture. [ABSTRACT FROM AUTHOR]

This article explores the use of laser shock peening (LSP) to enhance the fatigue life of turbine blades in the aerospace industry. LSP involves applying high-energy laser pulses to a metal surface, creating compressive residual stress in the subsurface layer. The article presents numerical simulation models that examine the effects of LSP on turbine blades, including the propagation of elastic-plastic waves and the formation of residual stress. The study also investigates the impact of peening parameters such as laser intensity and spot size on the distribution of residual stress. Experimental tests and finite element simulations were conducted on TC4 titanium alloy samples, similar in structure to turbine blades, confirming the effectiveness of LSP in inducing compressive residual stresses. The study was supported by the Government of Perm Krai and the Ministry of Education and Science of Russia. [Extracted from the article]

• Advancements in laser shock peening (LSP) for Mg and its alloys are introduced. • Process-microstructure relationships of LSP and Mg alloys are presented. • Relationship of LSP on residual stress and surface roughness formation is discussed. • LSP on mechanical, tribological, corrosion and wear-corrosion behaviors are studied. • Ongoing advances, scientific gaps, and suggestions for future trends are provided. Among the existing series of softer metals, magnesium (Mg) has attracted much attention due to its impressive strength-to-weight ratio. However, due to its ease of deformability, Mg tends to suffer from rapid degradation in a wide variety of abrasive and electrochemical environments. One method of improving its surface properties is through surface modification techniques. Among the existing techniques, laser shock peening (LSP) has been one of the most widely utilized processes due to its surface-hardening-like effects. Despite this understanding, a comprehensive review has yet to exist that encapsulates the strengthening mechanism of LSP for Mg and its influence in degradation environments. This review aims to encapsulate the existing research around the LSP field for Mg. Specifically, an understanding of the surface-strengthening effects in relation to its mechanical, tribological, corrosion, and tribo-corrosion characteristics is elucidated. Additionally, the feasibility of LSP for Mg materials in critical industries is also discussed. Through this work, a novel understanding of LSP for Mg can be understood, which can provide a future direction for research in this field. [ABSTRACT FROM AUTHOR]

Current methods for modeling hybrid additive manufacturing are computationally inefficient for use in optimization algorithms. An analytical tool is needed to understand how cycling thermal and mechanical loads via 3D printing and cold working reshapes cumulative residual stress within a build volume. A novel analytical model was developed that couples beam theory and superposition to rapidly predict cumulative residual stress. Modeling results were experimentally validated on AlSi10Mg after laser shock peening prescribed layers during powder bed fusion. Results demonstrated a vertically translating heat-affected zone, and the use of beam-based superposition accurately accounted for residual stress redistribution from cyclic printing and peening. [ABSTRACT FROM AUTHOR]

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High-strength steels offer potential for weight optimization due to reduced wall thicknesses in modern constructions. Additive manufacturing processes such as Wire Arc Additive Manufacturing (WAAM) enable the resource-efficient production of structures. In the case of defects occurring in weld seams or WAAM components due to unstable process conditions, the economical solution is local gouging or machining and repair welding. It is important to understand the effects of machining steps on the multiaxial stress state in conjunction with the design-related shrinkage restraints. Research into how welding and slot milling of welds and WAAM structures affects residual stresses is still lacking. For this reason, component-related investigations with high-strength steels with yield strengths ≥790 MPa are carried out in our research. In-situ digital image correlation (DIC) and ex-situ X-ray diffraction (XRD) were used to analyze the stresses and strains induced on specimens during and after milling. The systematic analyses revealed a significant interaction of the stiffness and microstructure of the specimens with the initial residual stresses induced by welding. Subsequent repair welds can result in significantly higher residual stresses. [ABSTRACT FROM AUTHOR]