Experimental Study on Residual Stresses of Al2O3 Coating by Laser Re-Melting

2010 ◽  
Vol 431-432 ◽  
pp. 446-449
Author(s):  
De Jun Kong ◽  
Kai Yu Luo ◽  
Hong Miao
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Tensile Stress ◽  
Residual Stresses ◽  
High Power ◽  
Bonding Strength ◽  
Strengthening Mechanism ◽  
Al2o3 Coating ◽  
Micro Hardness ◽  
Continuous Co2 Laser

The surface of Al2O3 coating sprayed on 40Cr substrate was re-melted with high power continuous CO2 laser, and its micro-hardness and residual stresses were measured, respectively. The strengthening mechanism of Al2O3 coating by laser re-melting was analyzed and discussed. The experimental results shown that the surface of Al2O3 coating by laser re-melting is neat and smooth, and its compositions are even, its structures are compact, and Al2O3 coating is evenly distributed in its surface with grain forms, and its micro-hardness increases about 200%; Residual stress of Al2O3 coating by laser re-melting is changed into compressive stress from tensile stress, which is benefit to improving bonding strength of coating-substrate interface.

Effects of Residual Stress on Interfacial Bonding Strength of Zinc-Plated Film

2010 ◽  
Vol 142 ◽  
pp. 112-116
Author(s):  
Xing Fang Wang
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Bonding Strength ◽  
X Ray Diffraction ◽  
X Ray ◽  
Influence Mechanism ◽  
Interfacial Structures ◽  
Interfacial Bonding Strength ◽  
Film Cracking

The distributions of residual stresses for zinc-plated film were measured quantitatively by X-ray diffraction (XRD), its interfacial structures were observed with scanning electron microscope (SEM). The effects of residual stress on bonding strength of zinc-plated film were investigated, and its influence mechanism was discussed. The experimental results show that residual stresses of zinc-plated film are behaved as tensile stress, which increase with its thickness, bonding strength of zinc-plated film is inverse ratio with residual stresses; the effects of residual stress on film crack are obvious, tensile stress speeds film cracking, which decrease its bonding strength; bonding strength of zinc-plated film is increased by improving its residual stress distribution.

A study on the residual stress measurement methods on chemical vapor deposition diamond films

1998 ◽  
Vol 13 (11) ◽  
pp. 3027-3033 ◽  
Author(s):  
Jung Geun Kim ◽  
Jin Yu
Keyword(s):  
Residual Stress ◽  
Chemical Vapor Deposition ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Vapor Deposition ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Peak Shift ◽  
Intrinsic Stress ◽  
Chemical Vapor Deposition Diamond

Diamond films were deposited on the p-type Si substrate with the hot filament chemical vapor deposition (HFCVD). Residual stresses in the films were measured in air by the laser curvature, the x-ray diffraction (XRD) dϕψ − sin2ψ, and the Raman peak shift methods. All of the measuring methods showed similar behaviors of residual stress that changed from a compressive to a tensile stress with increasing the film thickness. However, values of residual stresses obtained through the Raman and XRD methods were 3–4 times higher than those of the curvature method. These discrepancies involved the setting of materials constants of CVD diamond film, and determination of a peak shifting on the XRD and Raman method. In order to elucidate the disparity, we measured a Young's moduli of diamond films by using the sonic resonance method. In doing so, the Raman and XRD peak shift were calibrated by bending diamond/Si beams with diamond films by a known amount, with stress levels known a priori from the beam theory, and by monitoring the peak shifts simultaneously. Results of each measuring method showed well coincidental behaviors of residual stresses which have the stress range from −0.5 GPa to +0.7 GPa, and an intrinsic stress was caused about +0.7 GPa with tensile stress.

Analysis of Residual Stress Induced by Hand Grinding Process

2011 ◽  
Vol 681 ◽  
pp. 327-331 ◽  
Author(s):  
Sawsen Youssef ◽  
O. Calonne ◽  
Eric Feulvarch ◽  
P. Gilles ◽  
Hédi Hamdi
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Material Removal Rate ◽  
Surface Integrity ◽  
Material Removal ◽  
Removal Rate ◽  
Grinding Process ◽  
Cup Wheel

Grinding cup wheel is often used in the case of hand grinding which allows an important material removal rate but with secondary concern of surface integrity. Integrity is strongly affected by the process and consequently influences the surface behaviour in terms of resistivity to stress corrosion and crack initiation. This operation is difficult to master in terms of results on the surface and subsurface due to its manual nature. The paper presents results of an experimental study to investigate the residual stresses induced by this hand grinding process.

Microstructure, mechanical properties and residual stress distribution in pulsed tungsten inert gas welding of Ti–5Al–2.5Sn alloy

2018 ◽  
Vol 233 (10) ◽  
pp. 2030-2044
Author(s):  
Massab Junaid ◽  
Fahd Nawaz Khan ◽  
Muhammad Rashid Mirza ◽  
Mirza Nadeem Baig
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fusion Zone ◽  
Weld Line ◽  
Alloy Sheet ◽  
Inert Gas ◽  
Hardness Profile ◽  
Micro Hardness ◽  
Tungsten Inert Gas Welding ◽  
Zone Width

Pulsed tungsten inert gas welding with full penetration was performed on 1.6 mm thick Ti–5Al–2.5Sn alloy sheet. Hole-drill strain measurement method was employed to measure the distribution of residual stresses across the weld line. Tensile tests were performed on the specimens sectioned in transverse direction of the welded sample. The evolved microstructure in the welded zone was investigated by metallography and X-ray diffraction. Transverse residual stresses of tensile nature were present at different depths below the surface and decreased the yield strength and ultimate tensile strength. However, this decrease was not dependent on the maximum value of transverse residual stress. Fracture location was found to be dependent on the micro-hardness profile and fracture took place in base metal where micro-hardness was the lowest. Furthermore, the presence of tensile residual stresses in the welded sample had no influence on the fractured surface morphology. Peak current and background current had a significant influence on the fusion zone width, heat-affected zone width, and fusion zone grain size.

Residual Stress Analysis in Quenched Aluminum Alloy Plate Using the Contour Method

2016 ◽  
Vol 850 ◽  
pp. 167-174 ◽  
Author(s):  
Ya Nan Li ◽  
Yong An Zhang ◽  
Xi Wu Li ◽  
Zhi Hui Li ◽  
Guo Jun Wang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Experimental Measurement ◽  
Fem Simulation ◽  
Finite Element Method Simulation ◽  
Maximum Tensile Stress ◽  
Contour Method ◽  
Alloy Plate

A plate (30mm thick) of aluminum alloy 7085-T76 was quenched into water at room temperature after solution treated at 470°C. The quenching residual stresses distributions were studied by both experimental measurement and FEM (Finite Element Method) simulation. The experimental measurement was accomplished by using the contour method, and the FEM simulation was carried out to verify the experimental results. The experimental quenching residual stress distributions showed the tensile stresses of 74.8MPa ~109MPa in the center part, and compressive stresses of 29MPa-63.6MPa on the surface. The prediction distributions showed the maximum tensile stress of 98.2MPa in the center and the maximum compressive stress of 50.5MPa on the surface. The experimental quenching residual stresses distributions agree favorably with the prediction results. The deviations of the maximum tensile stress were less than 25MPa in the center. The deviations may be attributed to the accuracy of the contour method and the idealization of the prediction model.

Effects of Residual Stress on Interfacial Bonding Strength of WC Coating

2009 ◽  
Vol 16-19 ◽  
pp. 10-14
Author(s):  
De Jun Kong ◽  
F. Yuan ◽  
Hong Miao
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Bonding Strength ◽  
Flame Spraying ◽  
X Ray Diffraction ◽  
X Ray ◽  
Interfacial Bonding Strength ◽  
Stress Influences ◽  
Micro Structures ◽  
Coating Stress

The residual stresses of WC coating prepared by flame spraying and laser re-melting were measured quantitatively with X-ray diffraction (XRD) stress tester, and its micro-structures were observed with SEM, and the effects of residual stress on bonding strength of coating interface were analyzed. The experimental results are shown that residual stresses of WC coating are all tensile, and the effects of coating thickness on its residual stress is obvious, and residual stress is verse ratio with its thickness; Coating stress influences its cracking, tensile stress speeds its cracking, which causes its bonding strength decrease; The stress state is improved by decreasing its thickness, and its bonding strength can be increased.

scholarly journals Investigations into the Improvement of the Mechanical Properties of Ti-5Al-4Mo-4Cr-2Sn-2Zr Titanium Alloy by Using Low Energy Laser Peening without Coating

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1398
Author(s):  
Dingyuan Xue ◽  
Yang Jiao ◽  
Weifeng He ◽  
Xiaojun Shen ◽  
Yangjun Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Strength ◽  
Dynamic Equilibrium ◽  
Laser Energy ◽  
Strengthening Mechanism ◽  
Laser Peening ◽  
Micro Hardness ◽  
Laser Peening Without Coating

Mechanical properties, such as residual stress, micro-hardness and fatigue performance, of the Ti-5Al-4Mo-4Cr-2Sn-2Zr titanium alloy were improved via the laser peening without coating (LPwC) with a water-penetrable wavelength of 532 nm and pulse duration of 10 ns. In this paper, three kinds of laser energy, namely 85, 110 and 160 mJ were used to process the samples. The titanium alloy samples were also peened with different impact times (1, 3 or 5 impacts) at the energy of 85 mJ. The micro-hardness and residual stress distribution results provided that LPwC can introduce compressive residual stress (CRS) and also induce hardening of the target materials. Further, micro-hardness and CRS showed the increasing trends when the laser impact times increased. However, the CRS and micro-hardness decreased while the laser energy increased from 110 to 160 mJ, which was attributed to the dynamic equilibrium between the thermal and mechanical effects of LPwC. High cycle fatigue strength of the titanium alloy was significantly improved from 360 to 490.3 MPa after three impacts LPwC. The strengthening mechanism of fatigue strength subjected to LPwC was a combined effect between the laser-induced CRS and the high-density dislocations.

Relation between Residual Stresses in TBCs Interface Area with TGO Interface Morphology

2012 ◽  
Vol 151 ◽  
pp. 469-473 ◽  
Author(s):  
Zhi Yong Han ◽  
Hua Zhang
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Residual Stresses ◽  
Compressive Stress ◽  
Bond Coat ◽  
Maximum Stress ◽  
Ceramic Coating ◽  
Interface Morphology ◽  
Interface Area ◽  
Symmetrical Center

Considering the thermally-growth oxide (TGO) that grows between top ceramic coating (TCC)and bond coat (BC) interface and surface morphology of bond coat in a TBC system, the effect of residual stresses distribution by actual and assuming interface morphology in TGO area was calculated with ABAQUS. The calculating result shows that the residual stress of TCC/TGO and TGO/TCC interface are affected by interface morphology obviously, σyy is tensile at peaks and compressive at valleys for both with maximum stress beside the symmetrical center and at the symmetrical center respectively. σyy stress in TCC is bigger than that of BC for both. σxx stress of actual TGO in the three layers remains the same, the interim area change dramatically with TCC layer compressive stress, TGO layer smaller compressive stress, BC layer tensile stress.

Reaserch on Measurement of Residual Stresses in Flash-Butt-Weld Rails Using X-Ray Diffraction

2011 ◽  
Vol 291-294 ◽  
pp. 934-940 ◽  
Author(s):  
Shao Hua Yan ◽  
Hui Chen ◽  
Guo Qing Gou ◽  
Da Li ◽  
Yan Liu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Tensile Stress ◽  
Residual Stresses ◽  
X Ray Diffraction ◽  
Head Region ◽  
Butt Weld ◽  
X Ray ◽  
Railway Rail ◽  
Transverse Position ◽  
The Web

The residual stress,which is unavoidable in the process of flash-butt-weld rails,plays important roles in the service life of the railway rails.However,knowledge of magnitude,direction,and sign of the residual stress is useful for maintenance and failure prevention.In this paper,we measured the residual stresses in the flash-butt weld of the U71Mn railway rail,using X-ray diffraction method.Besides,we investigated the influence of grinding on residual surface stress.This investigation showed that residual stress generated by grinding could be removed by electro-polishing,we also found that there was longitudinal compressive stress in the foot and head region,while the web region presented tensile stress,and in the transverse position,all of the three regions existed both compressive and tensile stress.

Analysis of the Surface Residual Stress in Grinding Aermet100

2011 ◽  
Vol 704-705 ◽  
pp. 318-324
Author(s):  
Y.Q. Xu ◽  
T. Zhang ◽  
Y.M. Bai
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Thermal Expansion ◽  
Tensile Stress ◽  
Heat Source ◽  
Residual Stresses ◽  
Surface Grinding ◽  
Grinding Process ◽  
Surface Residual Stress ◽  
Abrasive Grains

Grinding induces residual stresses, which can play an important role on the fatigue of the component. In general, residual stresses in a ground surface are primarily generated due to three effects: thermal expansion and contraction during grinding, plastic deformation caused by the abrasive grains of the wheel and phase transformations due to high grinding temperature. It was found that thermal expansion and plastic deformation in the grinding process were the major causes of residual stresses. In this paper, an analysis model for the calculation of residual stresses induced by a surface grinding process on an ultrahigh-strength steel (Aermet100) workpiece is presented. Firstly, the stress distribution induces by thermal expansion was obtained base on the transient heat conduction equation and the thermal properties of Aermet100. All the calculations were based on the moving heat source solution which was modeled as a uniformly distributed, 2D heat source moving across the surface of a half-space, found in Carslaw and Jaeger. The results show that the near surface residual stress is predominantly tensile and that the magnitude of this stress increases with increasing heat flux values. Secondly, the plastic deformation caused by the abrasive grains of the wheel was simulated base on the grain-workpiece interaction. The chip formation process and the material removal mechanisms can be examined using the micro-scale approach. The results show that the residual stress induced by the grinding force itself is generally compressive which is smaller than the residual tensile stress induced by thermal stress. Therefore, the residual stress brought about by grinding operation is generally a tensile stress. This paper offers an insight into the mechanism understanding of thermal and mechanical residual stresses induced by surface grinding. Key words: grinding, residual stress, grain

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