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.

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.

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.

Measuring overload effects during fatigue crack growth in bainitic steel by synchrotron X-ray diffraction

2015 ◽  
Vol 71 ◽  
pp. 11-16 ◽  
Author(s):  
P. Lopez-Crespo ◽  
A. Steuwer ◽  
T. Buslaps ◽  
Y.H. Tai ◽  
A. Lopez-Moreno ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Bainitic Steel ◽  
X Ray Diffraction ◽  
X Ray

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.

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