• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.591-596
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• 2001

The purpose of this study is to examine the change of half value breadth and residual stress during fatigue process in S45C Steel by X-ray diffraction. For S45C Steel, the relationship between the change in fatigue damage of the specimen and the half value breadth, and residual stress of X-ray diffraction profiles during the fatigue processes has been investigated. The half value breadth(HVB) decreases in he early period of fatigue cycle. The change of HVB is relation to cyclic work hardening. In $10{\sim}20%$ of ratio of fatigue life, the change in the half value breadth is not marked. During fatigue process, the residual stress is changed with fatigue cycle increasing.

• Tribology and Lubricants
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• 제18권3호
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• pp.187-193
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• 2002

The half-value breadth off-ray diffraction profile line is generally used for a factor in nondestructive hardness measuring method of steel. In this paper, the problem in using the half-value breadth for the hardness measuring method is evaluated in strain hardened steel. And new hardness measuring method using residual stress is proposed X-ray diffraction test after rolling contact fatigue test of ball bearing with inner race of various hardness are carried out to measure the distribution of residual stress and half-value breadth from surface. The result of this study shows that there is little correlation between half-value breadth and hardness in the higher strength region and in the region increasing the hardness by strain hardening. But the magnitude of residual stress on/under race after rolling contact fatigue test becomes clearly to be correlative with hardness. Thus, it is concluded that the hardness of strain hardened steel can be estimated by this relationship between residual stress and hardness.

• 한국해양공학회지
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• 제8권1호
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• pp.114-122
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• 1994

X-ray stress constant, K, was determined for the diffraction line of (211)plane by using Cr-K$\alpha$ radiation. K was -340.87 MPa/deg. Fatigue crack propagation tests of SS41 steel were conducted under stress ratios of 0.1, 0.3 and 0.5. The half-value breadth of X-ray diffraction profile was measured at and beneath the fracture surface. The half-value breadth, B, on the fracture surface was found to increase with increasing $K_max$. The value of B was influenced by stress ratio in SS41 steel. The half-value breadth took the maximum value at the borden of reversed plastic zone, while it approached to the initial (pre-fatigue) value near the boundary of monotonic plastic zone. The maximum depth of the plasticzone was evaluated on the basis of the half-value breadth distribution. The depth $\omega$$_y$ is related to $K_max$by the following equation : $\omega$$_y$ = $\alpha$($K_max$/$\sigma$$_y$$)^2$ where .sigma.$\sigma$$_y$ is the yield strength obtength obtained in tension test .alpha.is 0.136 for SS41 steel.

• International Journal of Precision Engineering and Manufacturing
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• 제3권2호
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• pp.78-86
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• 2002

In general, X-ray diffraction method detects the changes of crystal lattice under material surface using the angle of diffraction 2$\theta$. This technique which deals with in the presented paper can be applied to a behavior on the slipped band or the micro crack cause to material degradation. The relation between half-value breadth and cycle numbers shows three stages, which consist of rapid decrease in the initial cycle, slight decrease in the middle cycle, and then rapid decrease in the final cycle. The ratio of half-value breadth has a constant value on B/B$\_$0/ - N diagram under the loading condition except early part of fatigue life. The ratio of half-value breadth B/B$\_$0/ - log N$\_$f/ with respect to number of cycle to failure N$\_$f/ has linear behavior on B/B$\_$0/ - log N$\_$f/ diagram. Therefore, the evaluation of fatigue life by the average gradient has much less mean error than the estimation of fatigue life by log B/B$\_$0/ - log N/N$\_$f/ relation.

• 한국정밀공학회지
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• 제17권1호
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• pp.145-152
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• 2000

X-ray diffraction method detects change of crystal lattice distance under material surface using diffraction angle 2$\theta$. This technique can be applied to the behavior on slip band and micro crack due to material degradation. The relation between half-value breadth and number of cycle has three stages which constitute rapid decrease in initial number of cycles, slight decrease in middle number of cycles and rapid decrease in final number of cycles. The ratio of half-value breadth takes a constant value on B/B$_{0}$-N diagram with loading condition except early part of fatigue life. The ratio of half-value breadth B/B$_{0}$ with respect to number of cycle to failure N$_{f}$ has linear behavior on B/B$_{0}$-log N$_{f}$ diagram. Therefore, in this paper the estimation of fatigue life by average gradient method has much less estimated mean error than the estimation of fatigue life by log B/B$_{0}$-log N/N$_{f}$ relation.elation.ation.

• 한국해양공학회지
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• 제7권2호
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• pp.103-113
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• 1993

X-ray diffraction analysis technique was used for the fatigue damage analysis and fatigue life prediction in Al 7075-T651 alloy. The tensile test, fatigue strength and fatigue crack propagation test with change of stress ratio were carried out. As a result, half-value breadth was increased with the plastic deformation in the specimen increasint at all test conditions. In particular, half-value breadth at the surface of the specimens fractured by fatigue was increased as stress intensity factor range and effective stress intensity factor range were increased. In addition, the good relationship between half-value breadty and diffraction pattern was shown.

• Tribology and Lubricants
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• 제19권1호
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• pp.1-8
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• 2003

Recently, PM-high speed steel(PM-HSS) has reportedly been a good alternative material for rolling mill because of its superior performance to conventional HSS. This paper has been aimed to investigate the possibility for application to rolling contact element for PM-HSS by X-ray diffraction technique. The X-ray elastic constant for PH-HSS has been found by X-ray diffraction during the four-point bending test. Residual stress and half-value breadth on the contact surface during rolling contact fatigue process by X-ray diffraction have also been measured. The result of this study shows that the application of X-ray diffraction technique to PM-HSS could be as possible alternative material as conventional HSS. Half-value breadth on rolling contact surface by X-ray diffraction is not changed during rolling contact fatigue process. On the other hand, the residual stress is changed. This suggests that dislocation reaction has been hardly occurred in rolling contact, depending on super-saturated carbon in PM-HSS.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.19-24
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• 1999

Understanding of wear mode and prediction of wear rate of parts in sliding contact are very important in field of meterial design relating with wear resistant. This paper has been undertaken to analyze the possibility of elucidation of wear mode and prediction of wear rate for annealed steel in sliding contact using the X-ray diffraction. The sliding wear test with various velocities using pin-on-disc machine and the X-ray diffraction test on the worn surface have been carried out. The results have been shown that the magnitude of residual stress and half-value breadth on the worn surface have a good correlation with wear mode. The difference between before and after test of half-value breadth on worn surface has been shown to be exponential relation with wear rate in the same wear mode.

• 한국해양공학회지
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• 제16권3호
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• pp.54-58
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• 2002

This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor; Kmax) and X-ray parameters (residual stress:$\sigma$r half-value breadth: B) for SG365 steel at elevated temperature up to 30$0^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of $\sigma$r-ΔK was established by the experimental data. therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• 한국정밀공학회지
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• 제19권4호
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• pp.117-123
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• 2002

X-ray diffraction observation of fracture surfaces yields useful information to analyze the causes of failure accidents of engineering structures. This experimental technique, named X-ray fractography, has been developed especially in metal and mechanical engineering fields. The distributions of the residual stress and the half value breadth of diffraction profiles beneath the fatigue fracture surface were measured with SNCM 439, HT100 and Ti-6Al-4V alloy. The size of the maximum plastic zone was successfully determined on the basis of the measured distributions. This size was correlated to maximum stress intensity factor. The distributions of the half value breadth of diffraction profiles on the fatigue fracture surfaces were measured with SNCM 439. HT100. The equations of x-ray parameter distribution were possible to estimated fracture parameters of fatigue fracture surfaces.