Mechanism of Compressive Residual Stress Introduction on Surfaces of Metal Materials by Water-Jet Peening

2010 ◽  
Author(s):  
Ryo Ishibashi ◽  
Hisamitsu Hato ◽  
Fujio Yoshikubo
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Shock Waves ◽  
Power Plants ◽  
Compressive Residual Stress ◽  
Water Jet ◽  
Pulse Load ◽  
Depth Profiles ◽  
Impact Processes ◽  
The Impact

Water-jet peening (WJP) has been applied to several Japanese nuclear power plants as a method of preventive maintenance against stress corrosion cracking. WJP introduces compressive residual stress reaching hundreds of micrometers in depth, comparable with shot peening (SP), and much smaller plastic deformation at the processed surfaces than SP does. The causes of these features are investigated from the perspective of the impact processes on the surfaces. Pulse-load propagation simulation through elasto-plastic calculations using a finite-element method program was applied to analyze the effects of various parameters of the impact processes on the depth profiles of the residual stress and the amount of plastic deformation on the surface of austenitic stainless steels processed with either WJP or the SP. The calculated depth profiles of residual stress and plastic deformation were similar in some degree to the experimental results of an XRD residual-stress analysis and a plastic-strain analysis using both cross-sectional hardness measurements and EBSD analysis. The analysis reveals that the depth of the compressive residual stress tends to increase as the size of the loaded spot during impact increases. The average and maximum observed load spots using WJP were 0.25 and 0.95 mm in diameter, respectively. These diameters were respectively 1.3 and 4.8 times as large as the calculated diameter of a load spot using SP. The reason that the depth of the compressive residual stress using WJP is comparable with that using SP is considered to be the fact that the sizes of the load spots during the impact with WJP are in the same range as those with SP. Shots impact the surface during the SP process, while shock waves generated by the extinction of cavitations impact the surface during the WJP process. The analysis reveals that the shots deform the surface locally with much higher surface pressure in the early stages of the impact, while shock waves deform the surface evenly throughout the wave passage across the surface. It is inferred from these analyzed results that the media impacting the surface make a difference in the hardness and microstructure of the processed surface.

scholarly journals Effect of Different Manufacturing Process Steps on the Final Residual Stress Depth Profile along the Process Chain of Autofrettaged Thick-Walled-Cylinders

2014 ◽  
Vol 996 ◽  
pp. 676-681 ◽  
Author(s):  
Horst Brünnet ◽  
Michael Hofmann ◽  
Nataliya Lyubenova ◽  
Dirk Bähre
Keyword(s):  
Residual Stress ◽  
Depth Profile ◽  
Manufacturing Process ◽  
Compressive Residual Stress ◽  
Design Tool ◽  
Process Chain ◽  
Technical Process ◽  
Depth Profiles ◽  
The Impact ◽  
Compressive Residual Stresses

Selectively induced compressive residual stress depth profiles are gaining increasing importance as design tool for internally pressurized components. Hydraulic Autofrettage (AF) is a well-known manufacturing process to induce pronounced compressive residual stresses. However, AF does not stand alone in the technical process chain. In this paper, results from neutron diffraction experiments performed on thick-walled cylinders are presented and compared to finite-element simulations with Abaqus/CAE. The impact on the final residual stress depth profile after pre-machining, Autofrettage and post-machining is discussed.

Prediction of Residual Stress Improvement by Water Jet Peening Using Cavitating Jet Simulation With Bubble Flow Model

2010 ◽  
Author(s):  
Masashi Fukaya ◽  
Ren Morinaka ◽  
Noboru Saitou ◽  
Hisamitsu Hatou ◽  
Yoshiaki Tamura ◽  
...  
Keyword(s):  
Residual Stress ◽  
Flat Plate ◽  
Power Plants ◽  
Compressive Residual Stress ◽  
Flow Model ◽  
Water Jet ◽  
Bubble Collapse ◽  
Bubble Flow ◽  
Bubble Pressure ◽  
Cavitating Jet

We developed the new method for predicting a region of compressive residual stress on the weld surface after water jet peeing (WJP), which is a preventive maintenance technology for nuclear power plants. A cavitating jet is impinged on the weld surfaces of structures in a nuclear reactor. Bubble collapse impact causes plastic deformation of the weld surface, and changes the residual stress from tensile to compressive. Compressive residual stress prevents the occurrence of stress corrosion cracking (SCC) on the weld surface. A cavitating jet vertically injected into a submerged flat plate was investigated. Tensile stress was introduced onto the surface of the stainless steel plate by grinding before WJP in the experiment. We numerically simulated impulsive bubble pressure that varied by microseconds in the cavitating jet with the “bubble flow model”. The bubble flow model simulates the abrupt time-variations in the radius and inner pressure of bubbles based on the Rayleigh-Plesset equation in a cavitating flow. The cavitation collapse energy was estimated based on the bubble pressure. The cavitation collapse energy was compared with the measured compressive residual stress on the flat plate after WJP. The radial range of the compressive residual stress from the jet center axis is one of the most important measures of performance of WJP. The radial range of the cavitation collapse energy corresponded to that of compressive residual stress with a prediction error of +/− 20% under different conditions of jet velocity and the distance between the jet nozzle and plate surface. The results confirmed that the method we developed for predicting the region of compressive residual stress after WJP was valid.

Heat Treatment Effects on Distortion, Residual Stress, and Retained Austenite in Carburized 4320 Steel

2014 ◽  
Vol 783-786 ◽  
pp. 692-697 ◽  
Author(s):  
Andrew Clark ◽  
Randy J. Bowers ◽  
Derek O. Northwood
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Retained Austenite ◽  
Compressive Residual Stress ◽  
Surface Residual Stress ◽  
Depth Profiles ◽  
Size And Shape ◽  
Austenite Content ◽  
Treatment Conditions ◽  
The Difference

The effects of heat treatment on distortion, residual stress, and retained austenite were compared for case-carburized 4320 steel, in both the austempered and quench-and-tempered condition. Navy C-ring samples were used to quantify both size and shape distortions, as well as residual stress. The austempering heat treatment produced less distortion and a higher surface residual stress. Both hoop and axial stresses were measured; the difference between them was less than seven percent in all cases. Depth profiles were obtained for residual stress and retained austenite from representative C-ring samples for the austempered and quench-and-tempered heat treatment conditions. Austempering maintained a compressive residual stress to greater depths than quench-and-tempering. Quench-and-tempering also resulted in lower retained austenite amounts immediately beneath the surface. However, for both heat treatments, the retained austenite content was approximately one percent at depths greater than 0.5 mm.

scholarly journals Incremental Hole-Drilling Method Vs. Thin Components: A Simple Correction Approach

2014 ◽  
Vol 996 ◽  
pp. 283-288 ◽  
Author(s):  
Esther Held ◽  
Simone Schuster ◽  
Jens Gibmeier
Keyword(s):  
Residual Stress ◽  
Thin Metal ◽  
Hole Drilling ◽  
Depth Profiles ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Metal Sheets ◽  
Drilling Method ◽  
Measured Strain ◽  
The Impact

The incremental hole-drilling method is a widely used technique to determine residual stress depth profiles in technical components. Its application is limited in respect to the components geometry, for instance the components thickness. In this paper, a direct correction of the measured strain relaxations is proposed to consider the impact of deviant geometries, here the component thickness, on the residual stress evaluation that moreover, allows the application of commercially available evaluation software. The herein proposed approach is based on finite element simulation of the incremental hole drilling. The simulated strain relaxations for thin metal sheets are evaluated with an algorithm as used in commercially available evaluation software (i) for uncorrected data as well as (ii) for strain data corrected by the proposed correction procedure. It is shown that the correction approach leads to a significant improvement of the measurement accuracy. Further, by means of the approach residual stress depth profiles in thin metal sheets can be as usual determined using commercial evaluation software for the incremental hole-drilling method regardless of the algorithm used, i.e. differential or integral.

Research about the Effect of Ultrasonic Impact on the Mechanical Property of Welded Cruciform Joint of P355NL1 Steel

2014 ◽  
Vol 644-650 ◽  
pp. 4748-4751
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Si Yong Lei ◽  
Jian Ping Shi
Keyword(s):  
Mechanical Property ◽  
Residual Stress ◽  
Grain Size ◽  
Compressive Residual Stress ◽  
Impact Machine ◽  
Ultrasonic Impact Treatment ◽  
Weld Toe ◽  
The Impact ◽  
Cruciform Joint ◽  
Scanning Electron

Surface treatment was carried out on the welded cruciform joint of P355NL1 steel by using the HJ-II-type ultrasonic impact machine. The ultrasonic impact current is 1.5A, the impact amplitude is 20 microns and ultrasonic impacting time is 5min. Tensile test was carried out for both treated specimen and un-treated specimen. The fracture observed with the scanning electron microscope of 6360LA type. The experimental results show that although the compressive residual stress can be obtained in the surface of weld toe area, and the grain size in the surface of welded cruciform joint can be refined, but the mechanical property of the welded cruciform joint of P355NL1 steel can not be improved through the ultrasonic impact treatment. The main reason is that the ultrasonic impact layer is only 70um, it is to thin to compared to the thickness of the specimen.

Modification of Microstrucure and Residual Stress on Friction Welding Surface of Titanium Alloy by Water-Jet Cavitation Peening

2011 ◽  
Vol 317-319 ◽  
pp. 429-435 ◽  
Author(s):  
Dong Ying Ju ◽  
Xin Mao Fu ◽  
Shun Na ◽  
Bing Han ◽  
Xiao Hu Deng
Keyword(s):  
Electron Microscopy ◽  
Residual Stress ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
Welded Joint ◽  
Water Jet ◽  
X Ray Diffraction ◽  
X Ray ◽  
Welding Surface ◽  
Scanning Electron

Water jet cavitation peening is applied to improve the strength and mechanical properties of the friction-welded joints of titanium alloys. Scanning electron microscopy observations of the microstructure of the welded joints and welded area before/after water jet cavitation peening confirm slip dislocation at the microstructure near the surface of the specimens. The residual stress on the surface of the welded joint is measured by X-ray diffraction. The results indicate the effect of peening time on the strength of compressive residual stress.

Control of the Mechanical Property on Machined Surface by a New Tool for Cutting-Burnishing Combined Process

2004 ◽  
Author(s):  
Toshiaki Segawa ◽  
Hiroyuki Sasahara ◽  
Masaomi Tsutsumi
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Compressive Residual Stress ◽  
Milling Process ◽  
Machined Surface ◽  
Combined Process ◽  
Machining Conditions ◽  
Residual Stress State ◽  
Key Factor ◽  
Resistance To Stress

We have developed a new tool that is called as the “Compressive Residual Stress Generating cutter” (CRSG cutter)[1]. The CRSG cutter can generate effective compressive residual stress within the machined surface concurrently with the milling process. It is expected to improve mechanical properties such as the fatigue life and the resistance to stress corrosion cracking. The purpose of this study is to investigate the possibility of controlling the residual stress state within the machined surface with varying the machining conditions using the CRSG cutter. It was shown that the quantity of the plastic deformation of the machined surface affects the residual stress. The setting of the machining conditions with the CRSG cutter can control the plastic deformation quantity. The cross feed width can change plastic deformation on the machined surface that is the key factor in order to control the residual stress within the machined surface.

Long Term Stability of Compressive Residual Stress Introduced in Alloy 600 by Water Jet Peening Under Elevated Temperature Environment

2011 ◽  
Author(s):  
Tadafumi Hashimoto ◽  
Yusuke Osawa ◽  
Masashi Kameyama ◽  
Shinro Hirano ◽  
Naoki Chigusa ◽  
...  
Keyword(s):  
Residual Stress ◽  
Elevated Temperature ◽  
Stress Relaxation ◽  
Compressive Residual Stress ◽  
Water Jet ◽  
Target Area ◽  
Pressurized Water ◽  
Plastic Deformations ◽  
Term Operation

Primary water stress corrosion cracking (PWSCC) in the weld metal of alloy600 is an issue of concern in a pressurized water reactor (PWR). As a countermeasure against PWSCC, water jet peening (WJP), which can change tensile residual stress into compressive residual stress, has been applied to welded joints. Microstructure in the target area of WJP has an influence of not only WJP but welding and machining. Especially machining introduces severe plastic deformations to the materials. So microstructure in the target area might lack thermal stability due to severe plastic deformation. Additionally the region that compressive residual stress by WJP is nearly up to 1mm from the surface of the target material. As PWRs are operated at about 596K for long term, the compressive residual stress by WJP may be relieved due to creep. In order to keep operating PWRs safety, the stability of the compressive residual stress by WJP at elevated temperature has been clarified. In this work, the results were obtained written below. As a result of thermal aging test, a relaxation of compressive residual stress at specimen surface layer occurred due to recovery of the plastic deformations by machining. This stress relaxation behavior followed Johnson-Mehl equation. However residual stress relaxation due to creep was very few. Therefore it has suggested that the compressive residual stress introduced in Alloy600 by WJP is confirmed to remain stable during long term operation under elevated temperature.

Optimization of Laser Peening Parameters Using Taguchi Method

2007 ◽  
Vol 10-12 ◽  
pp. 692-696 ◽  
Author(s):  
Yue Qing Sun ◽  
Jian Zhong Zhou ◽  
Yi Bin Chen ◽  
Shu Huang
Keyword(s):  
Residual Stress ◽  
Taguchi Method ◽  
Compressive Stress ◽  
Compressive Residual Stress ◽  
Residual Compressive Stress ◽  
Critical Parameters ◽  
Laser Peening ◽  
The Finite Element Method ◽  
Optimal Setting ◽  
The Impact

Using Taguchi method to optimize the critical parameters of laser peening (LP) is presented firstly. The objective of the study is to assess the impact of laser parameters on the laser peen strengthening for the 6061-T6 aluminum alloy and optimize the process parameters to achieve higher surface residual compressive stress. In order to reduce the process cost and time, the finite element method was applied to simulate the LP process. The Taguchi method is used to formulate the experimental layout and establish the order of predominance among the identified critical parameters, and predict the optimal setting for each process parameter. The results show that three parameters related to the magnitude of compressive residual stress imply different effects. Laser shot diameter ranks first, followed by pulse width and laser power in terms of their effects on the magnitude of compressive residual stress. The best combination of levels is given by the levels (3, 3, 2). The optimal result was confirmed with a superior ultimate surface residual compressive stress of 125MP.

Influence of Compressive Stress to the Corrosion Rate of Magnesium

2016 ◽  
Vol 713 ◽  
pp. 284-287 ◽  
Author(s):  
Tetsuya Kawai ◽  
Noriyuki Takano
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Corrosion Rate ◽  
Mechanical Strength ◽  
Compressive Stress ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Elastic Stress ◽  
The Body ◽  
The Other

Magnesium has made an attention as implant material. Because it is decomposed and absorbed in the body, and its mechanical strength is stronger than that of polymers. It is, however, reported that the corrosion rate increases under the compressive elastic stress. In the other hand, it decreases in the specimen whose surface is applied to compressive residual stress by laser shot peening. This implies that compressive plastic deformation reduces the corrosion rate. In the present paper, the corrosion rate of magnesium that was plastically deformed by uniform high compressive stress was researched. As the result, the corrosion rate decreased as the compressive stress increased.

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