Mechanical Characterization of Photoresist Polymer Coatings as a Function of Processing History

1991 ◽  
Vol 226 ◽  
Author(s):  
Kun Tong ◽  
Jeffery F. Taylor ◽  
Richard J. Farris
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Practical Importance ◽  
Uv Curing ◽  
Polymer Coatings ◽  
Curing Temperature ◽  
Processing Conditions ◽  
Stress Development ◽  
History Of ◽  
Different Origins

AbstractPhotoresist polymer coatings in the film-substratum systems usually generate selfinduced residual stress during processing. It is believed that the residual stress is the driving force for buckling, cracking and delamination of the polymer coatings. Analysis of the residual stress development during processing is of great interest and practical importance.Holographic interferometry technique has been developed for the direct measurements of general 2-dimensional stresses in thin films.[l] It turns out that it is a powerful technique to analyze residual stress development in polymer coatings during processing. By directly measuring the residual stress for each processing stage, the history of residual stress evolution can be closely followed and the residual stresses generated from different origins can be separated. By varying UV curing dosage, thermal curing temperature and the sequence of thermal and UV curing procedures, different residual stresses from various processing conditions can be comprehensively analyzed. Combining these data with mechanical properties of the coating offers valuable information for better understanding of the processing mechanism and enables one to optimize processing conditions for the best product capability.

Processing Optimization of Optical Lens in the Injection Molding

2013 ◽  
Vol 813 ◽  
pp. 161-164 ◽  
Author(s):  
Chao Ming Lin ◽  
Chih Kun Wang
Keyword(s):  
Residual Stress ◽  
Refractive Index ◽  
Residual Stresses ◽  
Processing Parameters ◽  
Processing Conditions ◽  
Fringe Order ◽  
Optimal Method ◽  
Optical Lens ◽  
Injection Molded ◽  
Processing Optimization

The processing conditions during the manufacturing have critical effects on the optical performances of the molded lenses including the refractive index, isochromatic fringe order, and the fringed pattern. The objective of this work is to investigate numerically some effects of the molding conditions on the residual stresses of injection molded lenses, and then to optimal the processing parameters for reducing the residual stresses using the Taguchi method. The results show the optimal method is able to improve the residual stress and to produce a good fringed pattern.

Residual Stresses and Workpiece Deformation Due to Polishing and Plating of Computer Hard Disk Substrates

1999 ◽  
Vol 121 (1) ◽  
pp. 32-40 ◽  
Author(s):  
B. E. Klamecki
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Residual Stresses ◽  
Processing Conditions ◽  
Bending Moments ◽  
Stress Distributions ◽  
Material Deformation ◽  
Removal Processes ◽  
Insight Into ◽  
Shape Data

Residual stress distributions due to plating and polishing were determined for nickel-phosphorus plated aluminum alloy disks. Knowledge of these stresses provides insight into the material deformation and removal processes, information as to the effects of processing conditions on residual stress magnitude and can also serve as a basis for development of models of material deformation and removal in polishing. Measured disk shape data was fitted to an analytical solution for plate displacement due to bending moments, and residual stresses were calculated. Plating and polishing residual stresses were separated. Polishing residual stress is compressive indicating differential plastic deformation between the surface and interior regions of the workpiece. Residual stresses produced in polishing operations in which process motions were constrained so that polishing was unidirectional were measured. The results show large differences between amounts of deformation in the polishing direction and the direction perpendicular to it.

scholarly journals Effect of Phase Transformations on Scanning Strategy in WAAM Fabrication

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7871
Author(s):  
Muhammad Hassaan Ali ◽  
You Sung Han
Keyword(s):  
Residual Stress ◽  
Additive Manufacturing ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Manufacturing Industry ◽  
Welding Process ◽  
Stress Generation ◽  
Temperature History ◽  
History Of ◽  
Wire Arc Additive Manufacturing

Due to its high production rates and low cost as compared to other metal additive manufacturing processes, wire arc additive manufacturing (WAAM) has become an emerging technology in the manufacturing industry. However, the residual stress generation and part distortion hinder its widespread adoption because of the complex thermal build-histories of WAAM parts. One of the ways to alleviate this problem is to consider the effects of scan strategies as it directly influences the thermal history of the built part. Since WAAM itself is an evolved welding process and even though it is evident from welding studies that phase transformations directly affect the residual stresses in welded parts, it remains unclear how the consideration of phase transformations for different scan strategies will affect the residual stresses and distortions in the WAAMed parts. A FEM study has been performed to elucidate the effects of phase transformations on residual stresses and the distortion for different deposition patterns. The current findings highlight that for the fabrication of low-carbon martensitic steels: The consideration of phase transformations for line-type discontinuous patterns (alternate and raster) do not significantly affect the residual stresses. Consideration of phase transformations significantly affects residual stresses for continuous patterns (zigzag, in–out and out–in). To accurately simulate complex patterns, phase transformations should be considered because the patterns directly influence the temperature history of the built part and will thus affect the phase transformations, the residual stresses and the warpage. During the fabrication of WAAM parts, whenever possible, discontinuous line scanning patterns should be considered as they provide the part with uniform residual stress and distortion. The alternate line pattern has been found to be the most consistent overall pattern.

On the Stress Development in SA508 Autogenous Weld

2014 ◽  
Vol 783-786 ◽  
pp. 2123-2128 ◽  
Author(s):  
Hamidreza Abdolvand ◽  
Mike Keavey ◽  
H. Dai ◽  
Alison Mark ◽  
N. O’Meara ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Phase Transformations ◽  
High Speed ◽  
Elevated Temperatures ◽  
Kinematic Hardening ◽  
Stress Development ◽  
Wide Range ◽  
Martensitic Phase Transformations ◽  
Welding Processes

Considering the significant role that residual stresses play in determining the lifetime-service of materials, it is mandatory to have a good understanding of and a means of predicting those that develop during welding processes. For this purpose, a User MATerial subroutine (UMAT) is developed to study the effects of various parameters that influence solid state phase transformations and residual stress evolution during welding of SA508 ferritic steel. The temperature dependent elastic and kinematic hardening parameters for each of the individual phases that can potentially develop during cooling from elevated temperatures are measured and are used for calculating stress development during low (75 mm/min) and high (300 mm/min) speed gas-tungsten arc welding (GTAW) on SA508 grade 3. These two speeds are selected to cover a wide range of cooling rates in the heat affected zone so that different phase proportions would be present. The results of the numerical simulations for residual stresses are compared against those measured by neutron diffraction. It is shown here that a low speed weld results in bainite formation whereas a high speed weld results in bainitic as well as subsequent martensitic phase transformations where each welding rate results in different residual stress development.

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.

scholarly journals Effects of Roughness on Stresses in an Oxide Scale Formed on a Superalloy Substrate

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 479
Author(s):  
Yang Zhao ◽  
Fan Sun ◽  
Peng Jiang ◽  
Yongle Sun
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Residual Stresses ◽  
Oxide Scale ◽  
Rough Surface ◽  
Alumina Scale ◽  
Growth Stress ◽  
Oxide Growth ◽  
Substrate Thickness ◽  
Roughness Effect

The effects of surface roughness on the stresses in an alumina scale formed on a Fecralloy substrate are investigated. Spherical indenters were used to create indents with different radii and depths to represent surface roughness and then the roughness effect was studied comprehensively. It was found that the residual stresses in the alumina scale formed around the rough surface are almost constant and they are dominated by the curvature rather than the depth of the roughness. Oxidation changes the surface roughness. The edge of the indent was sharpened after oxidation and the residual stress there was released presumably due to cracking. The residual stresses in the alumina scale decrease with increase in oxidation time, while the substrate thickness has little effect, given that the substrate is thicker than the alumina scale. Furthermore, the effect of roughness on the oxide growth stress is analysed. This work indicates that the surface roughness should be considered for evaluation of stresses in coatings.

scholarly journals Additive Manufactured 316L Stainless-Steel Samples: Microstructure, Residual Stress and Corrosion Characteristics after Post-Processing

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 182
Author(s):  
Suvi Santa-aho ◽  
Mika Kiviluoma ◽  
Tuomas Jokiaho ◽  
Tejas Gundgire ◽  
Mari Honkanen ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Sample Surface ◽  
Post Processing ◽  
Magnesium Chloride Solution ◽  
Manufacturing Method ◽  
Four Point Bending ◽  
Traditional Manufacturing ◽  
Processing Steps ◽  
Compressive Residual Stresses

Additive manufacturing (AM) is a relatively new manufacturing method that can produce complex geometries and optimized shapes with less process steps. In addition to distinct microstructural features, residual stresses and their formation are also inherent to AM components. AM components require several post-processing steps before they are ready for use. To change the traditional manufacturing method to AM, comprehensive characterization is needed to verify the suitability of AM components. On very demanding corrosion atmospheres, the question is does AM lower or eliminate the risk of stress corrosion cracking (SCC) compared to welded 316L components? This work concentrates on post-processing and its influence on the microstructure and surface and subsurface residual stresses. The shot peening (SP) post-processing levelled out the residual stress differences, producing compressive residual stresses of more than −400 MPa in the AM samples and the effect exceeded an over 100 µm layer below the surface. Post-processing caused grain refinement and low-angle boundary formation on the sample surface layer and silicon carbide (SiC) residue adhesion, which should be taken into account when using the components. Immersion tests with four-point-bending in the heated 80 °C magnesium chloride solution for SCC showed no difference between AM and reference samples even after a 674 h immersion.

Measurement of Residual Stresses in Linear Friction Welded In-Service Inconel 718 Superalloy

2016 ◽  
Vol 879 ◽  
pp. 1800-1806 ◽  
Author(s):  
M. Smith ◽  
L. Bichler ◽  
D. Sediako
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Material ◽  
Peak Stress ◽  
Weld Interface ◽  
Aerospace Alloys ◽  
Aero Engine ◽  
Linear Friction ◽  
Inconel 718 Superalloy ◽  
Residual Strains

Measurement of residual strains by neutron diffraction of linear friction welded Inconel® 718 (IN 718) superalloy acquired from a mid-service aero-engine disk was undertaken in this study. Residual strain and stress throughout the various weld regions including the heat affected zone (HAZ), thermomechanical affected zone (TMAZ) and dynamically recrystallized zone (DRX) were characterized. The residual stresses were observed to increase from the base material to the weld interface, with a peak stress at the weld interface in all orthogonal directions. The trends for residual stress across the weld are in agreement with other work published in literature for solid state welding of aerospace alloys, where high residual stresses were commonly reported at the weld interface.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

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