Magnitude Of Residual Stresses Research Articles

Residual stress analysis of plasma sprayed coatings through the weak magnetic field testing method

A proposed technique for swiftly evaluating coating stress variations involves utilizing weak magnetic detection under geomagnetic field conditions. This method examines the surface magnetic induction strength on uncoated test specimens, analyzing the magnetic induction change pre- and post-spraying. Employing the Almen test method, the assessment of specimen deflection and residual stress magnitude affirms the viability of weak magnetic detection for assessing coating residual stress. The experimental findings establish a direct link between the rate of magnetic induction intensity change and residual stress magnitude through polynomial fitting, suggesting that weak magnetic detection can preliminarily analyze coating stress variation.

Composite effects of residual stress and hardness gradient on contact fatigue performance of rough tooth surfaces and optimization design of detailed characteristic parameters

Residual stress and hardness gradient significantly affect the contact fatigue failure process of rough tooth surfaces, and the meticulous design of their characteristic parameters can help improve the fatigue resistance of gears. In this paper, an efficient computational method for rough tooth surface contact is established based on the reconstruction modeling of asperities and mixed lubrication analysis. By comprehensively considering the effects of residual stress and hardness gradient, the Dangvan multiaxial fatigue criterion is adopted to predict and analyze the contact fatigue life of the gear surface. The correlation between the surface residual stress, maximum residual stress depth, surface hardness, and effective hardening layer depth, among other characteristic parameters, and the contact fatigue performance of tooth surfaces is established. The results show that: (1) Increasing the magnitude of surface residual compressive stress and surface hardness can significantly reduce the risk of fatigue failure in the near-surface layer of the gear. To achieve the same fatigue performance, there is a linear negative correlation between the design values of the two parameters. (2) Affected by the double stress peaks in the rough tooth surface stress field, the maximum residual stress depth significantly affects the depth at which the highest failure risk occurs. With changes in roughness, the optimal design value of the maximum residual compressive stress depth changes from about 0.5 times the Hertzian contact half-width depth in the subsurface layer (Sa < 0.2 μm) to about 15 μm in the near-surface layer (Sa > 0.4 μm). (3) Considering both process cost and gear surface fatigue resistance, the design threshold for the effective hardening layer depth should be greater than the Hertzian contact half-width. This paper establishes a composite correlation between the meticulous characteristic parameters of residual stress, hardness gradient, and the contact fatigue performance of tooth surfaces, providing theoretical support for optimal design of tooth surface anti-fatigue performance.

Prediction of thermal shock induced cracking in multi-material ceramics using a stress-energy criterion

Impact of residual stresses on the thermal shock resistance of alumina–zirconia multi-layer ceramics is investigated within the framework of finite fracture mechanics, using astress-energy criterion. The critical temperature difference (ΔTc) for crack formation is strongly dependent on the magnitude of residual stress and the material’s strength. The predicted minimal spacing between cracks, critical time for crack initiation, and initial depth of the induced cracks are compared and discussed for different designs. An increase of up to ∼40 % in ΔTc is predicted for multi-material ceramics with athin alumina surface layer with compressive stresses, compared to bulk reference alumina.

Full-field measurement of residual stress in single-crystal diamond substrates based on Mueller matrix microscopy

In this work, a method has been proposed for fast-measuring full-field residual stress of diamond substrates based on Mueller Matrix (MM) microscopy. The measurement system features a polarization camera and a fixed compensator at 45° orientation, and real-time birefringence imaging can be performed. The magnitude and orientation of residual stress have been characterized by the stress-optical law. Optical-grade synthetic diamond substrates after laser-cutting and grinding have been measured. After laser-cutting samples exhibit a central region where stress orientation is shifted by −90° from the x-axis. After double-sided fine grinding, the average stress value is relatively low at 0.094 GPa, while single-sided fine grinding yields average stress of 0.142 Gpa, whereas double-sided rough grinding leads to 0.157 Gpa. Full-field stress distributions obtained from Raman images show consistent patterns. The research indicates that the MM-based method is a promising technique for detecting diamond substrate birefringence and characterizing its stress variation during fabrication.

Modelling of residual stress during curing of a polymer under autoclave conditions and experimental validation

This study develops a multi-scale predictive framework to study the cure kinetics of a polymeric resin under autoclave conditions. The novelty of the study includes evaluation of the cure performance such that the influence of porosity on the residual stress can be interpreted. A representative volume element based finite element model is developed which captures the cure rate and degree of cure under periodic boundary conditions. Resin cure kinetics and heat generation are coded in Fortran via user defined subroutines to capture the non-linear cure response. The autoclave system is simulated as a pressure and thermal load on the resin domain. It is found that an increase of porosity by up to 5%, decreases the level of residual stress by 35% when compared to an ideal configuration, i.e., a no porosity content. The magnitude of residual stress is further validated with XRD results and found to lie within 8%. The proposed model is robust to capture the cure phenomenon of a given thermoset polymer, given the cure kinetic parameters.

Experimental and numerical investigation on residual stress and deformation of welded I-section curved steel beams

This paper presents an experimental and numerical investigation on welding-induced residual stresses and deformations of in-plane curved welded I-section steel beams. Two welded curved beams with different curvatures were investigated. After welding the curved beam, the residual deformations were measured by a 3D scanner. The residual stresses were subsequently obtained through a high-precision sectioning method. The effects of curvature on the magnitude and distributions of residual deformations and stresses at the specific sections were analysed with the test results. It was found that the residual deformation gradually increased from the weld region to both ends of the flange plate, and the torsion in the web plate became severe with a decrease in curvature of the curved beam. Moreover, the welding process of the curved beam was simulated using the finite element (FE) method. The developed FE model was validated against the test results, and thereafter, parametric analyses were conducted to assess the influence of welding sequence, welding speed, and curvatures of the curved beam on the welding residual stresses and deformations. The numerical results demonstrated that the residual stresses and deformations were significantly influenced by welding speeds, but the influence from curvature of the curved beam was relatively small. Finally, a reasonable welding sequence, welding speed, and curvature of the curved beams were recommended.

Correlation of microstructure, mechanical properties, and residual stress of 17-4 PH stainless steel fabricated by laser powder bed fusion

17-4 precipitation hardening (PH) stainless steel is a multi-purpose engineering alloy offering an excellent trade-off between strength, toughness, and corrosion properties. It is commonly employed in additive manufacturing via laser powder bed fusion owing to its good weldability. However, there are remaining gaps in the processing-structure-property relationships for AM 17-4 PH that need to be addressed. For instance, discrepancies in literature regarding the as-built microstructure, subsequent development of the matrix phase upon heat treatment, as well as the as-built residual stress should be addressed to enable reproducible printing of 17-4 builds with superior properties. As such, this work applies a comprehensive characterisation and testing approach to 17-4 PH builds fabricated with different processing parameters, both in the as-built state and after standard heat treatments. Tensile properties in as-built samples both along and normal to the build direction were benchmarked against standard wrought samples in the solution annealed and quenched condition (CA). When testing along the build direction, higher ductility was observed for samples produced with a higher laser power (energy density) due to the promotion of interlayer cohesion and, hence, reduction of interlayer defects. Following the CA heat treatment, the austenite volume fraction increased to ∼35 %, resulting in a lower yield stress and greater work hardening capacity than the as-built specimens due to the transformation induced plasticity effect. Neutron diffraction revealed a slight reduction in the magnitude of residual stress with laser power. A concentric scanning strategy led to a higher magnitude of residual stress than a bidirectional raster pattern.

Quantitative evaluation of residual stress and microstructural effects on the surface hardness of machined Ti-6Al-4 V alloy with microscopic characterization techniques

The surface hardness of machined Ti-6Al-4 V components has a significant influence on the service performance and fatigue life. It’s acknowledged that the hardness value of machined surface is dependent on microstructure and residual stress, however, the quantification of their influence levels on surface hardness is still an unresolved issue, which limits the potential for further enhancing the mechanical property of machined parts. Furthermore, it’s difficult for current studies to fully reveal the mechanism of hardness fluctuation due to release of residual stress. To address these gaps, this study presents a novel method for quantitatively evaluating residual stress and microstructural effects on the machined surface hardness using microscopic characterization techniques. The microstructures of machined Ti-6Al-4 V workpiece were characterized by electron backscatter diffraction (EBSD), and the microstructural hardening effects were analyzed. The residual stresses release and evaluation were performed by the Focused Ion Beam-Digital Image Correlation (FIB-DIC) ring core method, then the surface hardening originated from residual stress and microstructural effects can be assessed by nano-indentation measurements. The results show that the surface hardness increase induced by the combined effects of compressive residual stress and microstructure, where the microstructural hardening can be strengthening by obtaining smaller grain size and high proportion low grain boundary, and the higher magnitudes of compressive residual stress can also enhance the hardness increase. The surface softening induced by compressive residual stress relaxation with no obvious microstructural alterations was observed and the maximum softening reached 14.54% in this study. The findings are beneficial for understanding the mechanical property strengthening mechanism of the machined parts.

Investigating the relationship between residual stress and micromechanical properties of blood vessels using atomic force microscopy.

The magnitude of vascular residual stress, an inherent characteristic exclusive to the vasculature, exhibits a strong correlation with vascular compliance, tensile resistance, vascular rigidity, and vascular remodeling subsequent to vascular transplantation. Vascular residual stress can be quantified by evaluating the magnitude of the opening angle within the vascular ring. For decellularized vessels, the vascular ring's opening angle diminishes, consequently reducing residual stress. The decellularization process induces a laxity in the vascular fiber structure within decellularized vessels. To investigate the interrelation between the magnitude of residual stress and the microstructure as well as mechanical properties of elastin and collagen within blood vessels, this study employed fresh blood vessels, stress-relieved vessels, and sections of decellularized blood vessels. Structural scanning and force map experiments on the surface of the sections were conducted using atomic force microscopy (AFM). The findings revealed well-organized arrangements of elastin and collagen within fresh vessels, wherein the regularity of collagen and elastin exhibited variability as residual stress declined. Furthermore, both stress-relieved and decellularized vessel sections exhibited a reduction in the mean Young's modulus to varying extents in comparison to fresh vessels. The validity of our experimental results was further corroborated through finite element simulations. Hence, residual stress assumes a crucial role in upholding the structural stability of blood vessels, and the intricate association between residual stress and the microstructural and micromechanical properties of blood vessels holds significant implications for comprehending the impact of vascular diseases on vascular structure and advancing the development of biomimetic artificial blood vessels that replicate residual stress. RESEARCH HIGHLIGHTS: In this inquiry, we scrutinized the interconnection amid vascular residual stress and the microscale and nanoscale aspects of vascular structure and mechanical function, employing AFM. We ascertained that residual stress assumes a pivotal role in upholding vascular microstructure and mechanical attributes. The experimental outcomes were subsequently validated through finite element simulation.

The prediction of residual stress of welding process based on deep neural network

The welding process has been an efficient method for producing essential and complex manufacturing parts in various industrial design fields. The post-weld residual stress can have detrimental effects on welded components. Therefore, systematic studies of residual stress are essential for evaluating welding behaviors and mechanisms in welded structures. They can provide a valuable reference and optimization for addressing residual stress relief. Numerical finite element analyses based on thermal-mechanical models offer a comprehensive approach to simulate real welding, providing a reliable means to determine and quantify the distribution of residual stress based on welding parameters and material properties. Furthermore, the finite element analysis is capable of generating adequate and dependable datasets in relation to the classical experiment. However, the finite element simulation is not considered an efficient method for predicting the magnitude and distortion of residual stress due to its high computational cost. A deep learning framework with powerful automatic learning abilities could potentially be used as an alternative method to efficiently predict residual stress. The purpose of the current study is to propose an innovative modeling approach for accurately and effectively predicting residual stress. A deep network model with Convolutional Neural Network using Adam optimization is integrated with numerical finite element analyses of a single-pass beam weld in SUS304 stainless steel. Finite element analysis is used to generate extensive residual stress datasets, which are partly used to train the deep network model and partly used for model validation. The deep network model aligns closely with the finite element analysis results, with a root-mean-square error (RMSE) of less than 12, an absolute fraction of variation (R2) of greater than 0.95, a mean absolute error (MAE) of less than 6.8 and a mean absolute percentage error (MAPE) of less than 1.1. Furthermore, this study highlights the potential advantage of using a deep network model with strong memory capabilities to directly predict residual stress for identical structural components and welding processes.

Residual Stress Generation in Additive Manufacturing of Complex Lattice Geometries

Residual stresses developed during additive manufacturing (AM) can influence the mechanical performance of structural components in their intended applications. In this study, thermomechanical residual stress simulations of the laser powder bed fusion (LPBF) process are conducted for both simplified (plate and cube-shaped) geometries as well as five complex lattice geometries fabricated with Inconel 718. These simulations are conducted with the commercial software package Simufact Additive©, which uses a nonlinear finite element analysis and layer-by-layer averaging approach in determining residual stresses. To verify the efficacy of the Simufact Additive© simulations, numerical results for the plate and cube-shape geometries are analyzed for convergence and compared to experimental residual stress results available in the literature. Numerical residual stress results are subsequently compared for five complex lattice geometries. Results suggest that lattice geometry can play a significant role in the distribution and magnitude of residual stresses, which are significant in some applications.

Heat-Treated Inconel 625 by Laser Powder Bed Fusion: Microstructure, Tensile Properties, and Residual Stress Evolution

AbstractThis work investigates the impact of different heat treatments on the evolution of the microstructure, tensile properties, and residual stresses of Inconel 625 (IN625) processed by laser powder bed fusion (LPBF). Applying a heat treatment is an essential step to mitigate the high residual stresses in the components produced by LPBF and, simultaneously, to design the mechanical properties of the components. A high magnitude of residual stress can involve deformation and reduce the fatigue resistance of the components. In the current work, heat treatments performed at 600, 800, and 870 °C provided minimal modification on the dimensions of the grains but involved the formation of new phases, which increased the tensile strength. The results showed mitigation of the residual stresses at 800 and 870 °C correlated with the formation of Cr-rich M23C6 carbides and δ phases, respectively. Finally, the solution annealing at 1150 °C triggered recrystallization with the formation of sub-micrometric carbides, reducing the residual stresses. The solution annealing treatment involved an improvement of the ductility and a reduction in tensile strength. This work provides a guide to understanding the microstructure, residual stress, and mechanical properties evolution of the IN625 alloy under heat treatments.

Investigation on the damage mechanism of micro-cutting surface layer of aluminum alloy 7075 with different heat treatment processes

This paper investigates the machinability and microscopic surface damage mechanisms of aluminum alloy 7075 subjected to different heat treatment processes during micro-cutting. Focusing on T6 and T73 heat-treated aluminum alloy 7075, the study employs a combination of experiments and simulations to analyze micro-cutting surface morphology, cutting forces, microstructure evolution, residual stress, and damage characteristics. The findings reveal that micro-cutting of aluminum alloy 7075 after T6 heat treatment exhibits no apparent speed sensitivity in the primary cutting force, while T73 heat treatment demonstrates noticeable speed sensitivity. The surface microscopic damage during micro-cutting is influenced by both cutting speed and depth, resulting in distinct forms and degrees of damage under varying conditions. An analysis of the residual compressive stress field indicates that the magnitude of residual compressive stress on the micro-cutting surface determines crack initiation, and the maximum depth of residual compressive stress dictates crack propagation. Microscopic damage in T6 heat-treated aluminum alloy 7075 predominantly occurs in the second and third deformation zones, while T73 heat treatment leads to most damage in the third deformation zone. Notably, crack propagation is evident in T6 heat treatment at any cutting speed with a cutting depth of 150 μm, whereas it is inconspicuous in T73 heat treatment at cutting speeds below 540 m/min. Furthermore, at cutting speeds below 540 m/min and a cutting depth of 150 μm, T6 heat-treated micro-cutting is prone to oxidative wear. In contrast, at a cutting speed of 72 m/min and a cutting depth of 150 μm, the predominant wear form in T73 heat-treated micro-cutting is oxidation wear. This study underscores the intricate interplay between heat treatment processes, cutting conditions, and microscopic damage in aluminum alloy 7075 micro-cutting. The nuanced insights provided contribute to a deeper understanding of the machining characteristics of this alloy, paving the way for improved processing methodologies.

Research of the vacuum thermocyclic nitrogen process in a plasma pulsing glow discharge

As a result of the studies, the regularities of the influence of vacuum thermocyclic nitriding in a pulsating glow discharge plasma parameters on the microhardness, the diffusion saturation depth, the magnitude and distribution of residual stresses in the hardened layers of steel surfaces are established. Based on the use of expert assessment methods and the results of a series of screening experiments, optimization criteria (endurance limit and corrosion resistance) and controlled factors for mathematical modeling of the formation of strengthened ion-nitrated surface layers are determined. A mathematical model of the technology of the formation of reinforced surfaces of the vacuum thermocyclic nitriding in a pulsating glow discharge plasma according to the criteria of endurance and corrosion resistance is obtained. An analysis of the studies showed that there are no general conclusions and recommendations on the selection of optimal technological parameters of the vacuum thermocyclic nitriding in a pulsating glow discharge plasma that would be used for the practical application of this technology. These circumstances confirm the need for further study of the vacuum thermocyclic nitriding in a plasma of a pulsating glow discharge of vacuum thermocyclic nitriding in a pulsating glow discharge plasma technology and the feasibility of its optimization.

Finite-element simulation of residual stresses induced by laser shock peening in TC4 samples structurally similar to a turbine blade

This study is devoted to the investigation of residual stresses distribution (RSD) in a TC4 sample treated with laser shock peening. The study placed special emphasis on analyzing the RSD at the part of the samples structurally similar to a turbine blade, which is more frequently subjected to damage during service according to the aircraft statistics. Results of simulation showed that low power density of 1.11 GWt/cm2 could not induce compressive residual stress on the surface of a treated object. Furthermore, increasing the overlapping of laser spots does not improve the situation and still fail to induce surface compressive residual stress at a laser intensity of 1.11 GWt/cm2. The compressive stresses occur only with the rise in power density. Reducing the spot size from 3 mm to 1 mm for the power density of 10 GWt/cm2 results in a 20% increase in the magnitude of compressive residual stress in the area of interest. Moreover, applying 35% overlapping further enhances this value. In addition to increasing the magnitude of residual stress, this approach also leads to a more homogeneous RSD of the treated material.

Determination of the Effect of Heat Input during Laser Welding on the Magnitude of Residual Stresses in the Refurbishment of Al Alloy Casting

The paper presents the results of research on the evaluation of the quality of coating layers made by a laser. The base material, which was Dievar steel (1.2343), was coated with a single layer using additional materials in the form of a wire with a diameter of ø 1.0 mm. As additional material, wires with chemistry corresponding to steels 1.2343 and 1.6356 were used. The primary objective was to verify the possibilities of innovative use of additive materials based on maraging steels, which were chosen from the production of two manufacturers with slightly different chemical compositions. The experiment verified the influence of the cladding parameters on the residual stress values around the fabricated maraging layers. Metallographic analysis by light microscopy was carried out in order to identify the individual structures as well as to assess the occurrence of internal defects in the coatings. The effect of the mixing of the coating metal with the base material was also assessed by means of a low-load hardness assessment, which was carried out in accordance with EN ISO 4063-2. Based on the results, it can be concluded that, in terms of residual stresses, the measured values were approximately the same for all the additive materials used; however, due to the desired mechanical properties of the additively formed layers, it is possible to recommend additive materials based on medium- and high-alloy steels for additive manufacturing.

Equivalent single layer approach for ultimate strength analysis of box girder under bending load

The objective of this study is to assess the ultimate strength of box girder using equivalent single layer (ESL) approach. Box girders, composed of stiffened panels, are subjected to a four-point bending load for the ultimate strength analysis. The results of ESL were validated using FEM and experiments. Modeling of ESL includes a single plate with the same stiffness as the actual stiffened panel topology, as opposed to traditional FEM modeling and test specimen, where the stiffener is explicitly modeled. For ESL approach, VUGENS subroutine in Abaqus software is used to define the non-linear stiffness properties. Material and geometric non-linearities were considered during simulations. The ESL stiffness matrix was derived from unit cell simulations under six loading conditions. In this case, a unit cell is a periodic structure that represents the entire stiffened panel model. Contact interaction is utilized to simulate the controlled movement of a hollow cylinder contacting a box girder, a precise modeling approach essential for comprehensive analysis. The explicit dynamic analysis is used to allow the large deformation and non-linear material behavior on stiffened panels. The effect of initial imperfection, residual stress, and stiffener slenderness on the ultimate strength was studied. The ultimate strength of a box girder is determined by its maximum bending moment. According to the results, the ESL model achieves results similar to the traditional FEM model and experiment. The accuracy of ESL to FEM in the ultimate strength assessment varies depending on the magnitude of residual stress and initial imperfection applied to the stiffened panel.

Влияние внутренних напряжений на интенсивность коррозионных процессов конструкционной стали

Introduction. The behavior of metal in a corrosive environment can be ambiguous, which is due to the peculiarities of the corrosion process. Both external and internal factors influence the corrosion process. External factors are determined by temperature, humidity, type of corrosive medium, etc., while internal factors depend on the parameters of the system (material): the presence of inclusions, phase composition, structure, and the magnitude of internal residual stresses. Internal factors ambiguously affect the behavior of the material in a certain aggressive medium, which ultimately affects the time of corrosion damage of the material and, as a consequence, the time of operation of objects made of this material. Therefore, differentiation of the influence of various internal factors on the rate of corrosion process in an aggressive environment is a priority area of research. The purpose of the present work is to consider the influence of the magnitude of internal residual stresses on the rate of corrosion process in an aggressive medium — 5% sulfuric acid solution. The object of research conducted in the work is sheet rolled steel St3 as received after different magnitude of plastic deformation, from which the specimens under study were made. The methods of investigation: microstructural study of deformed specimens was carried out on optical microscope Olympus GX53; software SIAMS 800 was used to compare the structure of the obtained material with the atlas of microstructures, determine the score of grain structure, determine the anisotropy of the structure after deformation of the material; X-ray diffractometer DRON-7 was used to register diffraction patterns and determine internal stresses; laboratory scales SHIMADZU UW620h was used to measure the mass of the specimens under study; tensile strength of the material’s specimens was measured. Results and Discussion. The obtained results show that the plastic deformation of the material in the rolling direction has an ambiguous effect on the structure anisotropy. When the degree of plastic deformation increases, there is an ambiguous change in the grain anisotropy value, which is associated with the internal effects of the processes occurring in the material structure during plastic deformation, such as: sliding of the crystal lattice in the {111} &lt;110&gt; directions; the occurrence of reverse residual internal stresses due to the presence of inclusions in the steel structure. However, the degree of plastic deformation correlates quite well with the magnitude of internal residual stresses. The increase in the magnitude of internal residual stresses leads to an increase in the corrosion rate of structural steel St3 in 5 % hydrochloric acid solution. The obtained dependence is described by a linear equation with a high coefficient of determination, which indicates that there is a strong relationship between the magnitude of internal residual stresses and the rate of corrosion of the material. At the same time, the coefficient of influence of internal stresses on the corrosion rate is equal to 0.72, which additionally proves the existence of interrelation between the considered parameters.

Effects of pre-tension and fatigue loadings on the evolution of welding residual stresses in welded plates

Welding-induced residual stresses evolve under external loading and fatigue actions. This paper examines the effects of a variety of influencing factors on the residual stress evolution, such as the pre-tension, load ratio, variable amplitude loading, overloading, plate thickness, and crack depth, for which a comprehensive understanding is yet to be nurtured. The experimental and numerical findings demonstrate that the variable amplitude loading and overloading impose significant effects on the evolution of residual stresses during the cyclic loading test. Based on the experimental observations and numerical analysis, this paper presents four evolution forms of residual stresses and reveals their mechanical principles by the effective stress-strain curves in both the undamaged specimens and the fatigue-cracked specimens. The interaction between the positions with different incremental plastic strains changes the magnitude of residual stress and thus dominates the residual stress evolutions.

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

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