Effect of Cavitation Number on the Improvement of Fatigue Strength of Carburized Steel Using Cavitation Shotless Peening

2004 ◽  
Vol 261-263 ◽  
pp. 1245-1250 ◽  
Author(s):  
D.O. Macodiyo ◽  
H. Soyama ◽  
Masumi Saka
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Cavitation Number ◽  
Material Surface ◽  
Carburized Steel ◽  
Upstream Pressure ◽  
Cavitating Jet ◽  
Cavitation Shotless Peening

Peening can be used to produce a layer of compressive residual stress at the surface of components which are subject to fatigue or stress corrosion, thereby retarding crack initiation and/or impeding the development of new cracks and hence improving their fatigue life. We have developed a new peening method, Cavitation Shotless Peening (CSP), which makes use of cavitation impacts induced by the collapse of the cavitation bubbles to produce compressive residual stress and work hardening on the material surface. CSP is a surface enhancement technique which differs with shot peening in that shots are not used. CSP uses a submerged high-speed water jet with cavitation, herein referred to as a cavitating jet, whose intensity and occurring region can be controlled by parameters such as upstream pressure and nozzle size. Cavitation number , which is defined by the ratio of upstream pressure to downstream pressure, is the main parameter of the cavitating jet. In this paper, the pit distribution on the specimen was observed with cavitating numbers  = 0.0057 and  = 0.0142. The improvement of fatigue strength and introduction of residual stress were investigated for both conditions using carburized alloy steel (JIS SCM415). It was evident from a comparison between non-peened and cavitation shotless peened specimens that the cavitation number has influence on the fatigue strength of metallic materials. Comparison of shot peened and CSP specimens has also been discussed.

Use of Cavitating Jet for Introducing Compressive Residual Stress

1999 ◽  
Vol 122 (1) ◽  
pp. 83-89 ◽  
Author(s):  
H. Soyama ◽  
J. D. Park ◽  
M. Saka
Keyword(s):  
Residual Stress ◽  
Exposure Time ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Water Jet ◽  
Material Surface ◽  
Principal Stresses ◽  
Plane Normal ◽  
Cavitating Jet

In an attempt to strengthen the surface of materials, the potential of using a cavitating jet to form compressive residual stress has been investigated. Introducing compressive residual stress to a material surface provides improvement of the fatigue strength and resistance to stress corrosion cracking. In general, cavitation causes damage to hydraulic machinery. However, cavitation impact can be used to form compressive residual stress in the same way as shot peening. In the initial stage, when cavitation erosion progresses, only plastic deformation, without mass loss, takes place on the material surface. Thus, it is possible to form compressive residual stress without any damage by considering the intensity and exposure time of the cavitation attack. Cavitation is also induced by ultrasonic, high-speed water tunnel and high-speed submerged water jet, i.e., a cavitating jet. The great advantage of a cavitating jet is that the jet causes the cavitation wherever the cavitation impact is required. To obtain the optimum condition for the formation of compressive residual stress by using a cavitating jet, the residual stresses on stainless steel (JIS SUS304 and SUS316) and also copper (JIS C1100) have been examined by changing the exposure time of the cavitating jet. The in-plane normal stresses were measured in three different directions on the surface plane using the X-ray diffraction method, allowing for the principal stresses to be calculated. Both of the principal stresses are found changing from tension to compression within a 10 s exposure to the cavitating jet. The compressive residual stress as a result of the cavitating jet was found to be saturated after a certain time, but it starts decreasing, and finally, it approaches zero asymptotically. It could be verified in the present study that it was possible to form compressive residual stress by using a cavitating jet, and the optimum processing time could also be realized. The great difference between the water jet in water and air has also been shown in this regard. [S1087-1357(00)00501-3]

Improvement of Fatigue Strength by Using Cavitating Jet in Air

2004 ◽  
Author(s):  
Hitoshi Soyama ◽  
Dan Macodiyo
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
High Speed ◽  
Diffraction Method ◽  
Water Jet ◽  
Bubble Collapse ◽  
Surface Residual Stress ◽  
Hydraulic Machinery ◽  
Rotating Bending Fatigue ◽  
Cavitating Jet

Cavitation normally causes severe damage in hydraulic machinery such as pumps and valves. However, the cavitation impacts at the bubble collapse can be used to enhance the surface of metallic materials just as the same way as shot peening. In case of peening using cavitation impact, the cavitation is produced by injecting a high-speed water jet in a water-filled chamber. The authors have already demonstrated the fatigue strength improvement of materials using a high-speed water jet in water. Recently the authors succeeded in producing a cavitating jet in air by injecting a high-speed water jet into a low-speed water jet using a concentric nozzle. Cavitating jet in air can be used to peen parts of plant which cannot peened by the water-filled chamber, thereby impeding the initiation and/or the development of cracks. In this study, in order to demonstrate the improvement of fatigue strength of materials using cavitating jet in air, stainless steel (JIS SUS316L) was peened and the residual stress measured using the X-ray diffraction method. The surface residual stress of non-peened and peened specimen was −68 MPa and −350 MPa, respectively. The fatigue strength of the specimen were then investigated using the rotating bending fatigue test, with a stress ratio of R = −1. The fatigue strength of peened specimen by cavitating jet in air improved by 20% compared with nonpeened specimen.

Introduction of Compressive Residual Stress Using a Cavitating Jet in Air

2004 ◽  
Vol 126 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Hitoshi Soyama
Keyword(s):  
Residual Stress ◽  
Mass Loss ◽  
Shot Peening ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Injection Pressure ◽  
Water Jet ◽  
Low Speed ◽  
Aluminum Specimen ◽  
Cavitating Jet

Cavitation impact from a cavitation jet, which is formed from bubbles induced by a high-speed water jet in water, can be used for surface modification in a similar manner to shot peening. A cavitating jet is normally produced by injecting a high-speed water jet into a water-filled chamber. It is possible to make a cavitating jet in air by injecting a high-speed water jet into a concentric low-speed water jet that surrounds the high-speed jet. In order to demonstrate this, a high-speed water jet with a concentric low-speed water jet was impacted onto an aluminum specimen to observe the pattern of erosion. The mass loss of the specimen was weighed to measure the capability of the jet, since a more powerful jet produces a larger mass loss. It was shown that the combination of high- and concentric low-speed water jets produced a typical erosion pattern such as that obtained using a cavitating jet in a water-filled chamber. When the injection pressure of the concentric low-speed water jet was optimized, the capability of the cavitating jet in air was much greater than that of a cavitating jet in a water-filled chamber. It was demonstrated that an optimized cavitating jet in air introduced more compressive residual stress in the surface of tool steel alloy than that from a cavitating jet in a water-filled chamber. In addition, this stress was larger than that induced by shot peening. The peened surface was also less rough compared with shot peening.

scholarly journals Stress Relaxation Behavior of Cavitation-Processed Cr–Mo Steel and Ni–Cr–Mo Steel

2019 ◽  
Vol 9 (2) ◽  
pp. 299
Author(s):  
Kumiko Tanaka ◽  
Daichi Shimonishi ◽  
Daisuke Nakagawa ◽  
Masataka Ijiri ◽  
Toshihiko Yoshimura
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
High Pressures ◽  
Relaxation Behavior ◽  
Material Surface ◽  
Stress Relaxation Behavior ◽  
Gas Atmosphere ◽  
New Processing

Cr–Mo steel and Ni–Cr–Mo steel have higher strength and hardness than carbon steel, and they are occasionally used in harsh environments where high temperatures and high pressures are simultaneously applied in an oxidizing gas atmosphere. In general, in order to improve the fatigue strength of a material, it is important to impart compressive residual stress to the material surface to improve crack resistance and corrosion resistance. Conventionally, the most famous technique for imparting compressive residual stress by surface modification of a material is shot peening processing. However, in shot peening processing, there is concern that particles adhere to the surface of the material or the surface of the material becomes rough. Therefore, in this study high temperature and high-pressure cavitation was applied and the material surface was processed at the time of collapse. A theoretical and experimental study on a new processing method giving compressive residual stress was carried out. In the present study, we will report stress relaxation behavior due to the heat of cavitation in processed Cr–Mo steel and Ni–Cr–Mo steel.

scholarly journals Surface modification of Cr‒Mo steel by new technology using high speed jet in water under ultrasonic irradiation

2018 ◽  
Vol 207 ◽  
pp. 03023
Author(s):  
Masataka Ijiri ◽  
Toshihiko Yoshimura
Keyword(s):  
Residual Stress ◽  
Corrosion Resistance ◽  
Surface Modification ◽  
Ultrasonic Irradiation ◽  
High Speed ◽  
Processing Time ◽  
Compressive Residual Stress ◽  
New Technology ◽  
Ultrasonic Power ◽  
Processing Times

In this study, to further improve current multifunction cavitation (MFC) techniques, the surface modification of Cr‒Mo steel was further investigated using 1200 W ultrasonic power. In MFC using 1200 W ultrasonic power, the corrosion resistance, and compressive residual stress of the specimens were improved when the processing time was 10 min; however, decarburization occurred at longer processing times, causing these characteristics to worsen. The decarburization that occurs at high ultrasonic outputs may be caused by an increase in the water temperature, and of the heating of the specimen surface.

A Study on the Fatigue Characteristics of Al6061-T651 by Shot Peening Velocity

2006 ◽  
Vol 326-328 ◽  
pp. 1093-1096 ◽  
Author(s):  
Won Jo Park ◽  
Sun Chul Huh ◽  
Sung Ho Park
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Shot Peening ◽  
High Speed ◽  
Compressive Residual Stress ◽  
Velocity Increase ◽  
Fatigue Characteristics ◽  
Height Increase ◽  
Small Steel

Small steel ball is utilized in Shot peening process. Called “shot ball” are shot in high speed on the surface of metal. When the shot ball hit the surface, it makes plastic deformation and bounce off, that increase the fatigue life by compressive residual stress on surface. In this study, the results of observation on the tensile strength, hardness, surface roughness, compressive residual stress and fatigue life of a shot peened Al6061-T651 were obtained. Experimental results show that arc height increase tremendously by shot velocity. Also, it shows that surface roughness, hardness, compressive residual stress and fatigue life increase as shot velocity increase.

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.

Improvement of Fatigue Strength of Aluminum Alloy by Cavitation Shotless Peening

2002 ◽  
Vol 124 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Hitoshi Soyama ◽  
Kenichi Saito ◽  
Masumi Saka
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Strength ◽  
Shot Peening ◽  
High Speed ◽  
Bending Fatigue ◽  
Hydraulic Machinery ◽  
Bending Fatigue Test ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Cavitation Shotless Peening

Cavitation impact, which normally produces severe damage in hydraulic machinery, can be used to modify surfaces in the same way as shot peening. Cavitation impact enables the surface of a material to be peened without the use of shot, thus it is called cavitation shotless peening. As there are no solid body collisions occurring in this peening process, the roughness of the peened surface should be less than that produced by shot peening. This characteristic makes it suitable for peening soft metals. In order to demonstrate the improvement of the fatigue strength of aluminum alloy by this process, specimens were subjected to the process, and then tested in a rotating bending fatigue test. Cavitation impacts were produced and controlled by using a submerged high speed water jet with cavitation, i.e., a cavitating jet. It was revealed that the fatigue strength of an aluminum alloy specimen treated by this peening process was 50% stronger than that of a specimen without peening.

scholarly journals Enhancement of Fatigue Strength on SAE 1541 Steel Link Plate with Slip Ball Burnishing Technique

2020 ◽  
Vol 70 (4) ◽  
pp. 454-460
Author(s):  
K. Krishnakumar ◽  
A. Arockia Selvakumar
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Strength ◽  
Compressive Residual Stress ◽  
Repeated Loading ◽  
Ball Burnishing ◽  
Novel Technique ◽  
Conventional Process ◽  
Chain Link ◽  
Local Plastic Deformation

This research paper describes a technique for the enhancement of the fatigue strength of the chain link plate in the drive system of a military armoured vehicle. SAE 1541 steel link plates of chains were subjected to cyclical tensile stress due to repeated loading and un-loading conditions. The crack was getting originated from the pitch hole and growth perpendicular to the chain pulling load, due to fatigue mechanism. In general plate holes are manufactured using the conventional process. An additional novel technique called the slip ball burnishing (SBB) method is applied for improving the hole properties. The improvement is made by producing local plastic deformation, improving surface finish and compressive residual stress throughout in the pierced hole. Both the conventional process (CP) and the SBB technique have been evaluated by optical, profile, surface roughness and micro harness tests. Experimental fatigue test validations were done in both chain samples using the Johnson-Goodman method. SBB chains passed 3x106 cycles at the load of 17.61 kN and CP chains passed 3x106 cycles at the load of 13.92 kN. The conclusion was that SBB made a significant improvement of 26.51 per cent of fatigue strength compared to CP.

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