• Title/Summary/Keyword: Surface residual stress

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A Study of Fatigue Crack Growth in Shot Peened Spring Steel (쇼트피닝한 스프링강의 피로균열진전 연구)

  • Park, Keyung-Dong;Jin, Young-Beom
    • Journal of the Korean Society of Safety
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    • v.19 no.4 s.68
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    • pp.20-24
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    • 2004
  • Antifatigue failure technology take an important the part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel and improving the fatigue strength on surface. Therefore in this paper the effect of compressive residual stress by shot peening on fatigue crack growth characteristics in stress ratio(R=0.1, 0.3, 0.6)was investigated with considering fracture mechanics. There is difference between shot peening specimen and unpeening specimen. Fatigue crack growth rate of shot peening specimen was lower than that of unpeening specimen. Fatigue lift shows more improvement in the shot peening material than in the unpeening material. And compressive residual stress of surface on the shot peening processed operate resistance force of fatigue crack propagation. That is the constrained force about plasticity deformation was strengthened by resultant stress, which resulted from plasticity deformation and compressive residual stress in the process of fatigue crack propagation.

Reduction of residual stress for welded joint using vibrational load

  • Aoki, Shigeru;Nishimura, Tadashi;Hiroi, Tetsumaro
    • Steel and Composite Structures
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    • v.4 no.5
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    • pp.355-365
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    • 2004
  • A new reduction method of residual stress in welding joint is proposed where welded metals are shaken during welding. By an experiment using a small shaker, it can be shown that tensile residual stress near the bead is significantly reduced. Since tensile residual stress on the surface degrades fatigue strength for cumulative damage, the proposed method is effective to reduction of residual stress of welded joints. The effectiveness of the proposed method is demonstrated by the response analysis using one mass model with nonlinear springs.

A Study on the Fatigue Crack of Material by Surface Non-Traditional Machining (표면특수가공에 따른 재료의 피로균열에 관한 연구)

  • 이태연;이승호;강진식
    • Transactions of Materials Processing
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    • v.10 no.3
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    • pp.179-184
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    • 2001
  • The influence of the fatigue crack propagation by shot peening was studied in this paper. Fatigue tests were carried out on the unpeened and shot peened CT specimens. The changes of mechanical properties, residual stress, fatigue fracture surface etc. by shot peening were investigated. The mechanical properties, residual stress, fatigue surface etc. by shot peening were investigated. The mechanical peened specimen improved in fatigue life up to 14% by shot peening. The reason of increase in the fatigue life was closely related with the compressive residual stress, which was 519.7MPa on surface. Another reason was the constraint on crack opening on surface region, it is due to the decrease in slope of crack propagation direction.

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Effect of Current Density and Solution pH on Properties of Electrodeposited Cu Thin Films from Sulfate Baths for FCCL Applications (Sulfate 용액을 이용하여 전기도금 한 FCCL용 Cu 필름의 특성에 미치는 전류밀도와 pH의 영향)

  • Shin, Dong-Yul;Park, Doek-Yong;Koo, Bon-Keup
    • Journal of the Korean institute of surface engineering
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    • v.42 no.4
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    • pp.145-151
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    • 2009
  • Nanocrystalline Cu thin films for FCCL were electrodeposited from sulfate baths to investigate systematically the influences of current density, solution pH on current efficiency, residual stress, surface morphology, and microstructure of thin Cu films. Current efficiencies were measured to be approximately 100%, irrespective of the applied current density and solution pH. But these influenced residual stress, surface morphology, XRD pattern, and grain size of electrodeposited Cu thin film. The residual stress decreased with decreasing the surface roughness, but increased with increasing the fcc(111) peak strength of XRD patterns.

A Study on the Residual Stresses by the Hole Drilling Measuring in the WeldZone (용접부의 천공 측정법에 의한 잔류 응력에 관한 연구)

  • NamKoong, Chai-Kwan
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.3
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    • pp.115-121
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    • 2008
  • A knowloedge of the residual stress distribution at circumferential welds can increase the prediction accuracy of a fracture assessment in pipe lines. In this study, in order to predict the residual stress distribution in the circumferential butt-welded pipes were measured, using the hole-drilling strain gauge method. Their practical applications were performed in to two kinds of pipes. As the results, the following characteristics were found. On the inner surface of pipes, the circumferential and axial residual stresses were both tensile near the center line of welding and both of them changed from tensile to compressive as the distance from the center line increased. On the outer surface, however, the circumferential residual stress was shown to be tensile wile the axial residual stress was compressive near the center line of welding, and later they were revered at the region far away from the centerline.

A study on the residual stresses in circumferential welds of the pipes (파이프 원주방향 용접부의 잔류응력 연구)

  • 남궁재관;홍재학
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.693-702
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    • 1991
  • The existence of residual stress in the circumferential butt welded pipes is one of the most important problems concerning stress corrosion cracking in service. In this paper, the residual stress distributions in three kinds of circumferential butt welded pipes were measured by the hole drilling strain gage method and calculation using finite element method is performed and its results are compared with the experiments. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed rom compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self restraint bending force in the pipe welding.

Residual Stress Measurement of Micro Gold Electroplated Structure (마이크로 금 전해 도금 구조물의 잔류응력 측정)

  • Baek, Chang-Wook;Ahn, Yoo-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.12
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    • pp.195-200
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    • 2000
  • In order to find a residual stress in the micro-machined beam, first natural frequency of the beam that has the residual stress inside is analyzed using the Rayleigh's energy method. Micro gold electroplated structure is fabricated by surface micro-machining process. The made structure is clamped-clamped beam and its 1st natural frequency is measured by resonance method. For the better estimation of the residual stress, an equivalent length of micro-machined beam to ideal beam is calculated by FEM. The residual stress is estimated from the equivalent length and the measured natural frequency.

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The Effects of the Drive-in Process Parameters on the Residual Stress Profile of the p+ Thin Film (후확산 공정 조건이 p+ 박막의 간류 응력 분포에 미치는 영향)

  • Park, T.G.;Jeong, O.C.;Yang, S.S.
    • Proceedings of the KIEE Conference
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    • 1998.11c
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    • pp.1007-1009
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    • 1998
  • In this paper, the effects of the drive-in process parameters on the residual stress profile of the p+ silicon film has been investigated. All the residual stress profile has been estimated by the second-order polynomial. All the coefficients of the polynomial have been determined from the measurement of the deflections of cantilevers and a rotating beam by using a surface profiler meter and by means of focusing a calibrated microscope. As the drive-in temperature or the drive-in time increases, the boron concentration decreases and the magnitude of the average residual stress decreases. If the boron concentration decreases the tensile residual stress decreases except near the surface where the magnitude of compressive residual stress increases.

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An Experimental Study on the Residual Stress Distribution at Circumferential Welds in Pipes (파이프 원주방향 용접부의 잔류응력분포 특성에 관한 실험적 연구)

  • Namkoong, Jae-Gwan;Hong, Jae-Hak
    • Journal of the Korean Society for Precision Engineering
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    • v.8 no.1
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    • pp.41-49
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    • 1991
  • A knowledge of the resdual stress distribution at circumferential weldments can normally increase the accuracy of a fracture assessment in pipe line. In this paper, we present the measurements about the residual stress distributions at three kinds of circumferential butt welded pipes using the holl drilling strain gage method. By this experiment, we have obtined the following characteristics. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed from compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self-restraint bending force in the pipe welding.

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Prediction of Axial Residual Stress in Drawn High-Carbon Wire Resulting Due to Increase in Surface Temperature (고탄소강 다단 신선 와이어의 표면 온도 상승에 의한 축방향 잔류응력 예측)

  • Kim, Dae-Woon;Lee, Sang-Kon;Kim, Byung-Min;Jung, Jin-Young;Ban, Deok-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1479-1485
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    • 2010
  • In recent times, due to wire drawing of high carbon steel at a high speed to ensure a high productivity and high strength, axial residual stress are generated because of rapid increase in surface temperature. In the process, the temperatures of the wires increased because of the deformation of the wires and the friction between the die and wire. In particular, in the case of the wire drawing at a high speed, friction leads to a large temperature gradient so that considerable axial residual stress is generated on the surface. In this study, the relationship between axial residual stress and increase in the surface temperature was investigated, and a prediction model of uniform temperature was proposed. Then, a prediction model for residual stress was developed. The proposed model was verified by measuring the residual stress by X-ray diffraction on drawn wires.