Residual stresses in polycrystalline Cu/Cr multilayered thin films

2000 ◽  
Vol 15 (3) ◽  
pp. 756-763 ◽  
Author(s):  
A. Misra ◽  
H. Kung ◽  
T. E. Mitchell ◽  
M. Nastasi
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Layer Thickness ◽  
Growth Stresses ◽  
Cu Films ◽  
Bilayer Films ◽  
Order Of Magnitude ◽  
Substrate Curvature

Residual stresses in sputter-deposited Cu/Cr multilayers and Cu and Cr single-layered polycrystalline thin films were evaluated by the substrate curvature method. The stresses in the multilayers were found to be tensile and to increase in magnitude with increasing layer thickness (h) to a peak value of ∼1 GPa for h = 50 nm. For h > 50 nm, the residual stress decreased with increasing h but remained tensile. The same trends were observed in single-layered Cu and Cr thin films, except that the maximum stress in Cu films is 1 order of magnitude lower than that in Cr. Transmission electron microscopy was used to study the microstructural evolution as a function of layer thickness. The evolution of tensile growth stresses in Cr films is explained by island coalescence and subsequent growth with increasing thickness. Estimates of the Cr film yield strength indicated that, for h ≥ 50 nm, the residual stress may be limited by the yield strength. Substrate curvature measurements on bilayer films of different thicknesses were used to demonstrate that a non-negligible contribution to the total stress in the multilayers arises from the interface stress.

Evaluation of the residual stress in stainless steel 304L hydraulically expanded joints

2020 ◽  
pp. 095440892096401
Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
The Finite Element Method ◽  
Power Stations ◽  
Stainless Steel 304 ◽  
Initial Clearance

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

Influence of deposition parameters on the residual stresses of WC-Wo sputtered thin films

MRS Advances ◽  
2020 ◽  
Vol 5 (23-24) ◽  
pp. 1215-1223
Author(s):  
R.R. Phiri ◽  
O.P. Oladijo ◽  
E.T. Akinlabi
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Residual Stresses ◽  
Substrate Surface ◽  
Tribological Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Deposition Parameters ◽  
Cobalt Thin Films

AbstractControl and manipulation of residual stresses in thin films is a key for attaining coatings with high mechanical and tribological performance. It is therefore imperative to have reliable residual stress measurements methods to further understand the dynamics involved. The sin2ψ method of X-ray diffraction was used to investigate the residual stresses on the tungsten carbide cobalt thin films deposited on a mild steel surface to understand the how the deposition parameters influence the generation of residual stresses within the substrate surface. X-ray spectra of the surface revealed an amorphous phase of the thin film therefore the stress measured was of the substrate surface and the effects of sputtering parameters on residual stress were analysed. Compressive stresses were identified within all samples studied. The results reveal that as the sputtering parameters are varied, the residual stresses also change. Optimum deposition parameters in terms of residual stresses were suggested.

X-Ray Diffraction and TEM Studies of the Delamination of Copper Thin Films from Glass and Silica Substrates

1989 ◽  
Vol 167 ◽  
Author(s):  
Alan G. Fox ◽  
Rowland M. Cannon
Keyword(s):  
Thin Films ◽  
Residual Stresses ◽  
Bragg Diffraction ◽  
Slight Reduction ◽  
X Ray Diffraction ◽  
Dislocation Generation ◽  
X Ray ◽  
Cu Films ◽  
Glass Substrates ◽  
Tensile Strains

AbstractThe events associated with fractures along interfaces between copper thin films and glass substrates were investigated by X-ray diffraction and transmission electron microscopy (TEM). In the as-bonded films the Bragg diffraction lines were shifted and broadened (relative to pure strain-free copper) due to residual in-plane tensile strains arising from the differences in thermal contraction between the copper and the substrates; TEM studies of these films in cross-section showed that the residual stresses had been relieved somewhat by dislocation densities as high as 1010 lines/cm2 in Cu/SiO2 films.The passage of a crack along the Cu/glass interfaces led to a significant reduction in the line shift and a slight reduction in the line broadening. Thus dislocations generated by the fracture events ‘plastically relaxed’ the residual stresses present in the as-bonded Cu by superposing a compressive component onto the pre-existing in-plane tensile strains. This dislocation generation was confirmed by TEM studies. In addition, it was found that the greater the strength of an interface, the greater was the reduction in mean strain due to the fracture; this is consistent with a larger crack-tip plastic zone and the generation of greater numbers of dislocations in the Cu films by fracture along interfaces of higher toughness (i.e. bond strength).

Abrasive Waterjet Peening With Elastic Prestress: Subsurface Residual Stress Distribution

2007 ◽  
Author(s):  
Balaji Sadasivam ◽  
Alpay Hizal ◽  
Dwayne Arola
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Field ◽  
Yield Strength ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Abrasive Waterjet ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Compressive Residual Stresses

Recent advances in abrasive waterjet (AWJ) technology have resulted in new processes for surface treatment that are capable of introducing compressive residual stresses with simultaneous changes in the surface texture. While the surface residual stress resulting from AWJ peening has been examined, the subsurface residual stress field resulting from this process has not been evaluated. In the present investigation, the subsurface residual stress distribution resulting from AWJ peening of Ti6Al4V and ASTM A228 steel were studied. Treatments were conducted with the targets subjected to an elastic prestress ranging from 0 to 75% of the substrate yield strength. The surface residual stress ranged from 680 to 1487 MPa for Ti6Al4V and 720 to 1554 MPa for ASTM A228 steel; the depth ranged from 265 to 370 μm for Ti6Al4V and 550 to 680 μm for ASTM A228 steel. Results showed that elastic prestress may be used to increase the surface residual stress in AWJ peened components by up to 100%.

The cracking and decohesion of thin films

1988 ◽  
Vol 3 (5) ◽  
pp. 1043-1049 ◽  
Author(s):  
A. G. Evans ◽  
M. D. Drory ◽  
M. S. Hu
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Yield Strength ◽  
Film Thickness ◽  
Elastic Properties ◽  
Fracture Resistance ◽  
Critical Values ◽  
Substrate Thickness ◽  
The Status ◽  
Ductile Substrates

The cracking and decohesion of thin films can be characterized by critical values of a nondimensional parameter governed by the residual stress, the film thickness, and a fracture resistance. This article reviews the status of understanding concerning the magnitude of this number for various types of adherent film on either brittle or ductile substrates. Important effects of elastic properties, substrate thickness, and yield strength are described.

Measuring the elastic modulus and residual stress of freestanding thin films using nanoindentation techniques

2009 ◽  
Vol 24 (9) ◽  
pp. 2974-2985 ◽  
Author(s):  
Erik G. Herbert ◽  
Warren C. Oliver ◽  
Maarten P. de Boer ◽  
George M. Pharr
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Expansion ◽  
Elastic Modulus ◽  
Dimensional Analysis ◽  
Experimental Verification ◽  
Cu Films ◽  
Proposed Model ◽  
The Difference

A new method is proposed to determine the elastic modulus and residual stress of freestanding thin films based on nanoindentation techniques. The experimentally measured stiffness-displacement response is applied to a simple membrane model that assumes the film deformation is dominated by stretching as opposed to bending. Dimensional analysis is used to identify appropriate limitations of the proposed model. Experimental verification of the method is demonstrated for Al/0.5 wt% Cu films nominally 22 µm wide, 0.55 µm thick, and 150, 300, and 500 µm long. The estimated modulus for the four freestanding films match the value measured by electrostatic techniques to within 2%, and the residual stress to within 19.1%. The difference in residual stress can be completely accounted for by thermal expansion and a modest change in temperature of 3 °C. Numerous experimental pitfalls are identified and discussed. Collectively, these data and the technique used to generate them should help future investigators make more accurate and precise measurements of the mechanical properties of freestanding thin films using nanoindentation.

Finite Element Welding Residual Stress Analysis of CRDM Penetration Nozzles

2021 ◽  
Vol 144 (1) ◽  
Author(s):  
Seung-Jae Kim ◽  
Eui-Kyun Park ◽  
Hong-Yeol Bae ◽  
Ju-Hee Kim ◽  
Nam-Su Huh ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Reactor Vessel ◽  
Welding Residual Stress ◽  
Alloy 600 ◽  
Stress Distributions ◽  
Control Rod ◽  
Residual Stress Analysis

Abstract This article investigates numerically welding residual stress distributions of a tube with J-groove weld in control rod drive mechanisms of a pressurized nuclear reactor vessel. Parametric study is performed for the effect of the tube location, tube dimensions, and material's yield strength. It is found that residual stresses increase with increasing the inclination angle of the tube, and the up-hill side is the most critical. For thicker tube, residual stresses decrease. For material's yield strength, both axial and hoop residual stresses tend to increase with increasing the yield strength of Alloy 600. Furthermore, axial stresses tend to increase with increasing yield strength of Alloys 82/182.

Residual Stress in Thin Films of Rf-Sputtered Aluminum by X-ray Multtaxial Stress Measurement

1995 ◽  
Vol 39 ◽  
pp. 433-438
Author(s):  
Shoukhi Ejiri ◽  
Zheng Lin ◽  
Tosihiko Sasaki ◽  
Yukio Hirose
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Multiaxial Stress ◽  
Argon Gas ◽  
X Ray

Residual stress in thin films of RF-sputtered aluminum coated on substrate of glass was measured by X-ray multiaxial stress measurement. The films were manufactured under the various conditions such as temperature of substrate ranged from 473K to 573K, and pressure of argon gas range from 0.0093Pato 13.3Pa respectively. These results brought comprehension that residual stress existed in tri-axial and that was influenced by temperature of substrate and pressure of argon gas. Residual stresses were unstable in range of less than 1.33Pa of pressure of argon gas.

Evolution of Residual Stresses in Thin Films Deposited on Mechanically Strained Substrates

1990 ◽  
Vol 203 ◽  
Author(s):  
G. Sheikh ◽  
A. Berger ◽  
I. C. Noyan
Keyword(s):  
Thin Films ◽  
Simple Model ◽  
Residual Stresses ◽  
Vapor Phase ◽  
X Ray Diffraction ◽  
Total Stress ◽  
X Ray ◽  
Cu Films ◽  
Residual Film ◽  
Nickel Substrates

ABSTRACTA simple model for the formation of residual stresses in thin films deposited on elastically strained substrates was derived and experimentally tested. In the experiments, Cu thin films were deposited on elastically stretched nickel substrates. These Cu films were2 to 4.m thick and were deposited through vapor phase evaporation or electroplating. The loads applied during the deposition were then relaxed, and the total stress in both the film and the substrate were monitored (by x-ray diffraction) during this relaxation. It was seen that the final (residual) film stresses were significantly different for bothdeposition methods. The causes of such differences are discussed.

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