Effect Of Residual Stress Distribution Research Articles

Effect of Residual Stress Distribution on the Rotating Bending Fatigue Properties of Shot Peening Treated Carburized Steel

Effect of Residual Stress Distribution on the Rotating Bending Fatigue Properties of Shot Peening Treated Carburized Steel

Effect of Residual Stress Distribution on the Formation, Growth and Coalescence of Voids of 27Cr White Cast Iron under Impact Loading

Effect of Residual Stress Distribution on the Formation, Growth and Coalescence of Voids of 27Cr White Cast Iron under Impact Loading

溶接継手の性能評価における残留応力分布の影響の考慮とその課題

溶接継手の性能評価における残留応力分布の影響の考慮とその課題

Effect of residual stress distribution in a log on lumber warp due to sawing: a numerical simulation based on the beam theory

When a squared lumber such as a beam and/or a bearer is produced from a log, they often show warps. Warp of the sawn lumber is practically not serious when the pith is located at the center of the cross-section, as in the lumber-with-pith, but causes serious problems in the lumber-without-pith. In the present study, a mechanical model was introduced to explain lumber warping based on beam theory, and a numerical simulation using the introduced model examined how the magnitude and type of the residual stress distribution would affect the warps of the lumbers sawn from the four-sided cants with various sizes and shapes in their cross-sections, and how the different sawing patterns would affect the production efficiency of the straight lumber, which is manufactured from the four-sided cant by quartering and subsequent correction sawing. As a result, the following suggestions were obtained. The warp of the sawn lumber is affected by the type and the magnitude of the inherent strain distribution in the log and furthermore by the cross-sectional shape and/or size of the four-sided cant. Production efficiency of the straight lumbers differs depending on the sawing patterns. In the present study, two types of sawing patterns (a) and (b) were assumed. The sawing pattern (a) gave better production efficiency than the sawing pattern (b) in the sense that straight lumbers are produced with higher volumes as well as with less variation in dimension of the cross-section.

Effects of Residual Stress Distribution on Interfacial Adhesion of Magnetron Sputtered AlN and AlN/Al Nanostructured Coatings on a (100) Silicon Substrate.

The present study investigated the influence of nanoscale residual stress depth gradients on the nano-mechanical behavior and adhesion energy of aluminium nitride (AlN) and Al/AlN sputtered thin films on a (100) silicon substrate. By using a focused ion beam (FIB) incremental ring-core method, the residual stress depth gradient was assessed in the films in comparison with standard curvature residual stress measurements. The adhesion energy was then quantified by using a nanoindentation-based model. Results showed that the addition of an aluminum layer gave rise to additional tensile stress at the coating/substrate interface, which can be explained in terms of the differences of thermal expansion coefficients with the silicon substrate. Therefore, the coatings without the Al layer showed better adhesion because of a more homogeneous compressive residual stress in comparison with the coating having the Al layer, even though both groups of coatings were produced under the same bias voltage. Results are discussed, and some general suggestions are made on the correlation between coating/substrate property combinations and the adhesion energy of multilayer stacks. The results suggested that the Al bond layer and inhomogeneous residual stresses negatively affected the adhesion of AlN to a substrate such as silicon.

Effects of case hardening properties on the contact fatigue of a wind turbine gear pair

Contact fatigue is an important issue in gear industry as it influences the reliabilities of mechanical equipment. Case-hardening processes could provide better mechanical properties by increasing the surface hardness and generating compressive residual stress. Yet these processes still cannot avoid contact fatigue problems and careful modeling is required. These processes generate gradients of mechanical properties below the surface, increasing complexities of contact analysis and fatigue life prediction. A numerical model is proposed to study the effect of the hardening layer on the carburized gear contact fatigue behavior. The gradients of the residual stress and the hardness are measured and the contact fatigue risk is evaluated using the concept of the material exposure. The effects of residual stress distribution, effective case depth, and surface-core hardness discrepancy on the contact fatigue performance of the gear are investigated. Results show that the contact fatigue of subsurface and the case- core transition area should both be evaluated to estimate the risk of pitting and tooth flank fracture.

Rolling contact fatigue of case carburized steels

Case carburized steels are widely used in high performance ball and rolling element bearings. They are characterized by the hardened exterior and gradient in the material properties as a function of depth. In this investigation, an elastic-plastic finite element model based on micro-indentation tests was developed to investigate the rolling contact fatigue of case carburized steels. A series of micro-indentation tests were conducted to obtain the hardness gradient in the case carburized 8620 steel. The results demonstrated that the hardness varies linearly from the surface to the core of the material. The finite element modeling approach employs Mises based plasticity model with kinematic hardening to incorporate the effect of material plasticity. The hardness gradient in the material was modeled by changing the yield strength as a function of depth. Linear relationship between hardness and yield strength was assumed. The FE model was coupled with continuum damage mechanics approach to capture material degradation due to fatigue damage. It considers both; stress and accumulated plastic strain based damage evolution laws for fatigue failure initiation and propagation. The residual stress distribution due to carburization process was modeled by modifying the damage evolution law. Material dependent parameters used in the damage evolution laws were determined using the SN results for torsional fatigue of the bearing steel. The effects of topological randomness in the material microstructure are accounted in the model through the use of Voronoi tessellations.The model was used to compare the rolling contact fatigue (RCF) lives of through hardened and case carburized bearing steel with different case depths at contact pressures ranging from 2 to 3.5GPa. The effect of residual stress distribution on RCF lives was also investigated. The results show that there is an optimum case depth for which maximum RCF lives can be attained. The spall shapes and the depth below the surface where damage initiates were found to be dependent on the case depth. The model was also used to study the effect of initial material imperfections. The fatigue lives and their dispersion quantified by Weibull slopes obtained from the model correlate well with the experiments.

転がり軸受の疲労特性に及ぼす残留応力分布の影響

転がり軸受の疲労特性に及ぼす残留応力分布の影響

Residual stress variation due to piping processes of austenitic stainless steel

In nuclear power plants, stress corrosion cracking (SCC) has been observed near the heat affected zone (HAZ) of the primary loop recirculation pipes made of austenitic stainless steel type 316L. Residual stress is a major cause of SCC. In the joining process of pipes, butt-welding is conducted after machining. Machining is performed to match the inside pipe diameter. Residual stress is generated by both machining and welding. In the case of welding after machining in manufacturing processes of pipes, it appears that residual stress due to machining is varied by the welding thermal cycle. In this study, residual stress variation caused by manufacturing processes was investigated. Residual stress variation was examined by the X-ray diffraction method. The residual stress distribution generated by welding after machining has a local maximum point in the HAZ. The Vickers hardness distribution also has a local maximum point. By the EBSD method, it is clarified that recovery and recrystallization due to welding heat do not occurred in the local maximum point. Residual stress distribution results from the superposition effect of hardening due to machining and welding. The location and value of the local maximum stress are varied by welding conditions. The region of the local maximum stress corresponds to the region where SCC has been observed. Therefore, in addition to a part of the manufacturing processes such as welding or machining, evaluation of all parts of the processes is important to investigate the effect of residual stress distribution on SCC.

OS0827 SCCの発生位置とき裂進展評価に用いる残留応力の扱いに関する検討

Effects of residual stress distribution on crack growth evaluation were confirmed by crack growth analyses for stress corrosion cracking (SCC) occurred in a butt welded pipe intended for primary loop re-circulation pipings in BWRs. In order to calculate stress intensity factor (SIF) for SCC growth evaluation, a semi-elliptical surface crack in a plate modeling shown in the JSME Code, Rules on Fitness-for-Service for Nuclear Power Plants, was applied. Weld residual stress and stress due to internal pressure were considered. SCC crack growth evaluation was conducted for a variety of crack positions which mean applied weld residual stress is different for each position. Comparisons of these results show rigorous measurement of a crack position is insignificant for crack growth evaluation.

Study on effect of residual stress distributions on kinetics of static strain aging after cold rolling

In the present research, the effect of residual stress distribution on the static strain aging (SSA) phenomenon in cold rolled steel was investigated. A three-dimensional model was employed to evaluate the residual stress distributions within the rolled strips, and hole drilling experiments were also performed to verify the data obtained from the mathematical model. Hardness and tensile tests were then performed on the cold rolled samples at different temperatures and aging periods, and the results of these tests were utilised to assess SSA behaviour after different rolling programs. The results show that SSA occurs within the cold rolled steel in the employed aging period, and its kinetics is affected by residual hydrostatic stresses. Additionally, the variation in residual hydrostatic stress distribution due to deformation path, e.g. single- and two-pass rolling layouts, slightly affects the activation energy of SSA and changes the kinetics of SSA after cold rolling.

The Effects of Residual Stress Distribution and Component Geometry on the Stress Intensity Factor of Surface Cracks

The stress intensity factor estimated by the appropriate modeling of components is essential for the evaluation of crack growth behavior in stress corrosion cracking. For the appropriate modeling of a welded component with a crack, it is important to understand the effects of residual stress distribution and the geometry of the component on the stress intensity factor of the surface crack. In this study, the stress intensity factors of surface cracks under two assumed residual stress fields were calculated. As residual stress field, a bending type stress field (tension-compression) and a self-equilibrating stress field (tension-compression-tension) through the thickness were assumed, respectively. The geometries of the components were plate and piping. The assumed surface cracks for those evaluations were a long crack in the surface direction and a semi-elliptical surface crack. In addition, crack growth evaluations were conducted to clarify the effects of residual stress distribution and the geometry of the component. Here, the crack growth evaluation means simulating increments of crack depth and length using crack growth properties and stress intensity factors. The effects of residual stress distribution and component geometry on the stress intensity factor of surface cracks and the appropriate modeling of cracked components are discussed by comparing the stress intensity factors and the crack growth evaluations for surface cracks under residual stress fields.

Effects of residual stress distribution on the cracking of thick freestanding diamond films produced by DC arc jet plasma chemical vapor deposition operated at gas recycling mode

Chemical vapor deposited diamond thick films for electronic and optical applications must be released without cracks from substrates as freestanding wafers. In the present investigation, the residual stress distribution of diamond thin films deposited by DC arc jet plasma chemical vapor deposition (CVD) at gas recycling mode was analyzed based on wave number shifts in their Raman spectra. The results show that residual compressive stress concentrates at the film's edge, and this residual stress increases with the increase in deposition temperature. Experimental observation also showed that cracks initiated at the edge of the diamond thick wafer and then propagated towards the center. Effects of the residual stress distribution on diamond thick films detachment were discussed. To release the residual stress, sandwich structure was designed and the metal interlayer was inserted between the diamond films and the substrate. Thick freestanding diamond films (more than 1 mm thick, 60 mm in diameter) were produced by DC arc jet plasma CVD process using Mo substrate with Ti interlayer.

表面き裂の応力拡大係数とき裂進展挙動に及ぼす残留応力分布および部材形状の影響―溶接残留応力場におけるＳＣＣき裂進展評価（第２報）―

Stress intensity factor estimated by using an appropriate modeling of components is essential for evaluation of crack growth behavior in stress corrosion cracking. For the appropriate modeling of welded components with a surface crack, it is important to understand the effects of residual stress distribution and the geometry of component on the stress intensity factor of the crack. In this study, stress intensity factors of surface crack under two assumed residual stress fields were calculated. As the residual stress fields, bending type stress field (tension-compression) and self-equilibrating stress field (tension-compression-tension) through the thickness were assumed. The geometries of welded components were set to plate and piping. The assumed surface cracks for evaluations were long crack in the surface direction and semi-elliptical surface crack. Furthermore, the crack growth evaluations were conducted to understand the effects of residual stress distribution and the geometry of component. From the comparison of stress intensity factors and crack growth evaluation for surface crack under residual stress fields, the effects of residual stress distribution and the geometry of component on the stress intensity factor of surface crack and on the appropriate modeling of cracked components were discussed.

Morphological aspects of fatigue crack propagation Part II—effects of stress biaxiality and welding residual stress

In order to maintain structural integrity of welded structures, it is of great importance to evaluate the fitness for serviceability of the structural components, in which fatigue cracks are found during in-service inspections. Crack propagation paths are sometimes prerequisite for the proper estimation of fatigue crack propagation, because curved crack paths and sharp crack turning could occur at the intersections of structural members mainly due to stress biaxiality of repeated loads. In order to investigate this fatigue crack-growth behavior, fatigue crack-propagation tests and numerical simulation are carried out under various biaxial stress range ratios. Morphological mode transitions of fatigue failures are observed in experiments and also by computer simulation. Although simulated modes of failures are in fairly good agreement with the experimental results, discrepancies are sometimes observed for the crack-propagation lives. In order to investigate this problem, the welding residual stresses in the test specimens are measured, and the fatigue crack-propagation lives are quantitatively examined in terms of the combined effects of residual stress distribution and crack paths.

Effect of flow rate on fatigue crack growth behaviour of A533B steels in high temperature pressurized water: Ktada, Y., Nagata, N. and Stoh, S. J. Soc. Mater. Sci. Jpn (Nov. 1992) 41 (470), 1648–1654 (in Japanese)

Case carburized steels are widely used in high performance ball and rolling element bearings. They are characterized by the hardened exterior and gradient in the material properties as a function of depth. In this investigation, an elastic-plastic finite element model based on micro-indentation tests was developed to investigate the rolling contact fatigue of case carburized steels. A series of micro-indentation tests were conducted to obtain the hardness gradient in the case carburized 8620 steel. The results demonstrated that the hardness varies linearly from the surface to the core of the material. The finite element modeling approach employs Mises based plasticity model with kinematic hardening to incorporate the effect of material plasticity. The hardness gradient in the material was modeled by changing the yield strength as a function of depth. Linear relationship between hardness and yield strength was assumed. The FE model was coupled with continuum damage mechanics approach to capture material degradation due to fatigue damage. It considers both; stress and accumulated plastic strain based damage evolution laws for fatigue failure initiation and propagation. The residual stress distribution due to carburization process was modeled by modifying the damage evolution law. Material dependent parameters used in the damage evolution laws were determined using the SN results for torsional fatigue of the bearing steel. The effects of topological randomness in the material microstructure are accounted in the model through the use of Voronoi tessellations.The model was used to compare the rolling contact fatigue (RCF) lives of through hardened and case carburized bearing steel with different case depths at contact pressures ranging from 2 to 3.5 GPa. The effect of residual stress distribution on RCF lives was also investigated. The results show that there is an optimum case depth for which maximum RCF lives can be attained. The spall shapes and the depth below the surface where damage initiates were found to be dependent on the case depth. The model was also used to study the effect of initial material imperfections. The fatigue lives and their dispersion quantified by Weibull slopes obtained from the model correlate well with the experiments.

炭素鋼同種摩擦圧接継手接合部の疲労き裂進展抵抗について

In order to evaluate the resistance to growth of fatigue cracks propagating along the weld interface of friction welded butt joints composed of carbon steel/carbon steel, a series of fatigue crack growth tests were carried out on S25C/S25C and S45C/S45C joints under three different cyclic load conditions. To investigate the effect of residual stress distribution in the specimen introduced in friction welding process on the crack growth behavior, two types of CCT plate specimens with a thickness of 2mm were prepared for respective carbon steel joints; one was the specimen as welded and another was the residual stress relief treated specimen. And the results of these joint specimens were discussed in comparison with those of the annealed CCT base metal plate specimens. First of all, whole crack growth behavior was investigated under increasing ΔK condition, and then the dependence of crack growth rate on the weld interface location was studied under a constant ΔK condition, and finally the ductility of the weld interface was evaluated indirectly through the observation of crack growth retardation behavior induced by the application of single static over-load during crack growth under constant ΔK. The results indicate that the residual stress does not play an important role on the fatigue crack growth of the joints, and metallurgical feature of the weld interface governs the fatigue crack growth behavior of the joints. And, the decrease in crack growth rate of the joint specimens by the application of the over-load is less than that of respective base metals, which indicates that the ductility of the weld interface of both joints is less than that of respective base metals.

Evaluation of the Strength of Carburized Spur Gear Teeth Based on Fracture Mechanics : 1st Report, Stress Intensity Factor Considering the Effect of Residual Stress Distribution in the Case

A method is presented to calculate the stress intensity factor of carburized spur gear teeth considering the effect of residual stress in the case. The crack at the fillet is assumed to be straight along the face width and a two-dimensional finite element method is used for the calculation. The residual stress is estimated based on the assumption that the main cause of residual stress is the volume difference between the case and core due to the martensitic transformation in cooling. The result demonstrates that the stress intensity factor is consideraly influenced by the residual stress. especially for the loading condition corresponding to the fatigue strength of gears. The present method is applied to the prediction of the position of crack initiation by assuming the existence the initial short cracks in the decarburized layer along the fillet.

On the Effect of Residual Stresses on Column Strength

The subject of inelastic buckling of columns and flat plates has been studied by several investigators.1) Residual stresses have considerable effects on the inelastic buckling strength of columns, and several researches have hitherto been reported on this problem.3)4) Especially, Osgood made a clear analysis on the column with a simple rectangular cross section, assuming an ideally plastic material and an unfavorable distribution of residual stress, which showed a remarkable reduction of column strength.2)The authors extended the analysis to the case of favorable distribution of residual stress, and also to the case of material with a linear strain-hardening characteristic. Although the analysis failed to give an explicit expression of the column strength, the column curves could be drawn by taking successively arbitrary values for the amount of spread of the plastic region. The theoretical column curves showed a noteworthy difference between the two cases of favorable and unfavorable distributions of residual stress.Experiments were carried out to verify the analysis. Two sorts of materials, low and medium carbon steels, were used as specimens. The dimension of the cross section was 6×9mm, the length being variously changed to give the slenderness ratios from about 40 to 100. The specimens were tested in a special device prepared for this purpose. The transverse deflection as well as the axial diaplacement were measured by two dial gages, respectively. As the treatment introducing residual stresses, low temperature quenching (quenched from 700°C into ice-water) and machining by a shaper (depth of cut was 1mm) were adopted, of course, the former giving unfavorable and the latter favorable distributions of residual stress. The residual stress distribution was measured by the X-ray film method, using CrKα beams. Thin layers were etched off successively from both sides of the specimen, and the surface residual stress was measured each time by the sin2ψ method. The original distribution of residual stress was obtained by using the correction formula.5) The experimental results showed considerably lower values as compared with the theoretical ones, due probably to the eccentricity of axial loading and the initial curvature of the column etc., however, a marked effect of residual stress distribution on the column strength was verified.