INTRODUCTION OF MACRO-STRAIN WITH RELEASING MICRO-STRAIN BY CAVITATION SHOTLESS PEENING

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1680-1685
Author(s):  
HITOSHI SOYAMA
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Metallic Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Forging Die ◽  
Cavitation Shotless Peening

When cavitation bubble is collapsed, shock wave which can deform metallic materials is produced. Cavitation impacts can be used for surface modification to enhance fatigue life of metallic materials in the same way as shot peening. As a peening method using cavitation impact does not require shots in shot peening, it is called “cavitation shotless peening CSP”. Although CSP can introduce compressive residual stress, i.e., macro-strain into metallic materials, full width at half maximum of diffractive X-ray profile was decreased by CSP. In the present paper, tool alloy steel for forging die was chosen as tested material to investigate mechanism of improvement of fatigue life, as CSP improved the life time of the forging die. The introduction of macro-strain was revealed by measuring residual stress, which was evaluated by X-ray diffraction method. The fatigue life was investigated by using a plate bending fatigue test changing with processing time of CSP. The micro-strain was evaluated by a fundamental parameter approach, which is one of X-ray diffraction method. It was concluded that the fatigue life of the steel was improved about 90 times by CSP and CSP can introduce macro-strain, i.e., compressive residual stress and releasing micro-strain. The micro-strain becomes about 1/20 of heat treated specimen by CSP.

A Study on Fatigue Crack Propagation Properties Using the X-Ray Diffraction Method

2008 ◽  
Vol 575-578 ◽  
pp. 1162-1169
Author(s):  
Md. Anowar Hossian ◽  
Man Bae Lim ◽  
Sun Chul Huh ◽  
Won Jo Park
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Stress Effect ◽  
X Ray Diffraction ◽  
X Ray

This study evaluated fatigue crack growth characteristics, Besides consider compressive residual stress effect and verified the most suitable shot peening velocity. Fatigue crack growth delay effect was compressive residual stress, but over peening did action projecting velocity that accelerate fatigue crack growth rate. X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. Fracture mechanics parameters could be estimated by the measurement of X-ray parameters, and the fractography observation was performed using a scanning electron microscope (SEM) for fatigue fracture surface. As the shot peening velocity increases, striation width increased. The changes in X-ray material parameters described above are directly related to the process of fatigue until the initiation of fatigue crack and X-ray diffraction pattern is thought that failure prediction with stress distribution is possible.

Characteristics of Residual Stress in P92 Steel Welds

2007 ◽  
Vol 26-28 ◽  
pp. 1175-1180
Author(s):  
Keun Bong Yoo ◽  
Hyun Sun Choi ◽  
Eui Hyun Kim ◽  
Jae Hoon Kim
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Welding Residual Stress ◽  
Distribution Characteristics ◽  
X Ray Diffraction ◽  
P92 Steel ◽  
X Ray ◽  
Steel Welds ◽  
Directional Difference

Welding residual stress has important influence on the performance of engineering components. In this paper, the residual stress and FWHM were measured by X-ray diffraction method to investigate characteristics for P92 steel welds. The aim of the study is to estimate the residual stress and FWHM distribution characteristics. A compressive residual stress distributed as a function of depth has a different pattern in welds and base metal. A large tensile residual stress occurs welds and near the HAZ, but approaches gradually zero as away from the welding center. Residual stress and FWHM undergo rapid relaxation after PWHT. Also, FWHM is a scalar quantity without any directional difference and is proportional to hardness on the whole.

Shakedown During Fatigue of Residual Stresses Introduced by Different Mechanical Surface Treatments

2006 ◽  
Author(s):  
Christopher M. Gill ◽  
Philip J. Withers ◽  
Alex Evans ◽  
Neil Fox ◽  
Koichi Akita
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Glass Bead ◽  
Compressive Residual Stress ◽  
Cold Work ◽  
Diffraction Method ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cold Worked

A layer of compressive residual stress extending from the surface of a component can help to extend fatigue life, but it must remain stable during applied service loading. Metal shot and glass bead peening are traditionally used; introducing a shallow (100–300μm) layer of compressive residual stress and a highly cold worked surface. Laser peening and deep rolling are capable of introducing much deeper compressive residual stresses combined with lower levels of cold work. In this paper we report on the level of shakedown of residual stress brought about by constant strain amplitude fatigue. Glass and metal shot peened, laser peened and deep rolled Ti-6Al-4V samples have been studied. The residual stress profiles as a function of depth have been measured using neutron diffraction, laboratory x-ray diffraction and a hybrid hole-drilling/laboratory x-ray diffraction method. The magnitude and depth of cold work determined for each of the treatment methods. The extent of subsequent residual stress shakedown under different strain amplitudes and load ratios, in deep rolled, glass bead and metal shot peened samples is also assessed.

Relationship between Compressive Residual Stress Relaxation and Microhardness Reduction after Cyclic Loads on Shotpeened ASTM A516 Grade 70 Steel

2018 ◽  
Vol 765 ◽  
pp. 232-236 ◽  
Author(s):  
Mohd Rashdan Isa ◽  
Omar Suliman Zaroog ◽  
Fareg S. Ali
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Shot Peening ◽  
Cyclic Load ◽  
Compressive Residual Stress ◽  
Hardness Test ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Load ◽  
Hardness Values

Shot peening process is a cold performed function to enhance the mechanical properties which is widely used in many industries. This process introduces compressive residual stress which was proven to increase the fatigue life, geometry stability and corrosion resistance. However, the benefit of the residual stress is still unstable due to the relaxation during the operation. This paper will study on the trend of the relaxation of residual stress against cyclic loading as well as the change in the hardness. The material used in this study is carbon steel ASTM A516/ SA 516 Grade 70. Shot peening process with steel shots was applied to the samples to introduce compressive residual stress in the samples. Cyclic load was applied to samples after shot peening process with low load of 52Mpa (20% of Yield Strength) and high load of 208Mpa (80% of Yield Strength). The measurement of residual stress using X-Ray diffraction and hardness test was done on the samples to study the trend of the relaxation of residual stress and the change in hardness values. The result shows that more relaxation of residual stress occurs if the applied cyclic load is higher. The change of hardness trend is found non-sequenced in this study due to random coverage of shot peening.

scholarly journals Precision of the Residual Stress determined by X-ray Diffraction: Summery and Limits

2019 ◽  
Author(s):  
Eckehard Mueller
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Round Robin ◽  
Surface Treatments ◽  
X Ray Diffraction ◽  
Measurement Standard ◽  
Passenger Cars ◽  
Round Robin Test ◽  
X Ray ◽  
Mechanical Surface

Today components specially for passenger cars are weight optimized. Often it is done by mechanical surface treatments. Therefore, the amount of compressive residual stress induced by the treatment must be known. The measurement is very often done by x-ray diffraction. But how precise can you determine (and not directly measured) the amount? A big question is the calibration of the equipment. A specimen must be designed and calibrated by round robin test, because no measurement standard is available.

Experimental Investigation on Intensity and Residual Stress in Superficial Layers Induced by Water Cavitation Peening with Aeration

2008 ◽  
Vol 373-374 ◽  
pp. 754-757 ◽  
Author(s):  
Dong Ying Ju ◽  
B. Han
Keyword(s):  
Residual Stress ◽  
Process Capability ◽  
Diffraction Method ◽  
Spring Steel ◽  
Bubble Collapse ◽  
Process Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Enhancement Method ◽  
The Impact

Water cavitation peening (WCP) with aeration is a novel surface enhancement method. A new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration, a standard N-type almen strips of spring steel SAE 1070 was treated by WCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by X-ray diffraction method. The optimal fluxes of aeration and the optimal standoff distances were achieved.

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.

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