The Experts below are selected from a list of 14403 Experts worldwide ranked by ideXlab platform
R B Rogge - One of the best experts on this subject based on the ideXlab platform.
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the role of Residual Stress in neutral ph Stress corrosion cracking of pipeline steels part ii crack dormancy
Acta Materialia, 2007Co-Authors: Weixing Chen, G. Van Boven, R B RoggeAbstract:Abstract This investigation provides a quantitative analysis of the effect of Type I Residual Stresses on the occurrence of pitting and Stress corrosion cracking (SCC) formation in pipeline steel exposed to neutral pH aqueous environments. It has been shown that SCC generated in neutral pH environments can be readily blunted due to plastic deformation (room temperature creep) and/or extensive anodic dissolution. As a result, a high positive Tensile Residual Stress gradient is necessary for continued growth of SCC in pipeline steels exposed to this neutral pH environment. The Tensile Residual Stress represents a large mechanical driving force for crack nucleation and short crack growth. Active cracks may become dormant as the near-surface Residual Stress gradient changes, due to self-equilibration, from highly Tensile to a lower Tensile state or to a compressive state. The change in Residual Stress level can occur within 1 mm of the surface, resulting in a large proportion of dormant SCC.
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the role of Residual Stress in neutral ph Stress corrosion cracking of pipeline steels part i pitting and cracking occurrence
Acta Materialia, 2007Co-Authors: G. Van Boven, Weixing Chen, R B RoggeAbstract:Abstract In this investigation, Tensile test specimens were fabricated with increasing levels of compressive and Tensile Residual Stress on the surface and through the thickness of the specimen. These Residual Stresses were then measured by neutron diffraction at multiple points along the length and through the depth of the specimens. The specimens were then exposed to a neutral pH aqueous soil environment in combination with an applied cyclic Stress for various lengths of time in order to initiate and propagate Stress corrosion cracking (SCC). The formation of micro-pitting was found to occur preferentially in areas where the Tensile Residual Stresses were the highest (approximately 300 MPa), while SCC initiation occurred with a 71% normalized frequency in areas where the surface Residual Stress was in the range 150–200 MPa. The difference between Residual Stress levels occurring at SCC locations versus pitting locations resulted from both the change of Residual Stress during cyclic Stress application during SCC testing and the Residual Stress gradient in the depth direction.
Naoyuki Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Unique fatigue threshold and growth properties of welded joints in a Tensile Residual Stress field
International Journal of Fatigue, 1997Co-Authors: Akihiko Ohta, Naoyuki Suzuki, Yoshio MaedaAbstract:Abstract The fatigue threshold and high growth rate region properties were investigated on several kinds of welded joints. These properties became unique in spite of the variation of steels (ferrite-pearite, martensite, austenite), welding method, heat input and Stress ratio. It was revealed that the unique properties occurred from the fully opened fatigue crack due to the Tensile Residual Stresses. Based on these results, the equation of the fatigue crack growth curve for the design and inspection of welded structures was proposed. It is also suggested that the inducement of compressive Residual Stress at the fatigue critical zone is effective in improving the fatigue properties of welded structures.
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fatigue crack propagation in a Tensile Residual Stress field under a two step programmed test
International Journal of Fatigue, 1993Co-Authors: Akihiko Ohta, A J Mcevily, Naoyuki SuzukiAbstract:Abstract Fatigue crack propagation rates were measured under two-step programmed loading for a centre-cracked specimen of 9Cr-2Mo steel in which a high Tensile Residual Stress field had been previously induced. This Tensile Residual Stress makes the actual Stress ratio at the crack tip high enough to avoid crack closure. Therefore the applied range of Stress intensity factor ΔK coincided with the effective range ΔK eff , and as a result no transitional behaviour in the rate of fatigue crack propagation occurred after a sudden change in ΔK .
A J Mcevily - One of the best experts on this subject based on the ideXlab platform.
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effects of surface deformation and crack closure on fatigue crack propagation after overloading and underloading
International Journal of Fatigue, 2004Co-Authors: Chobin Makabe, Anindito Purnowidodo, A J McevilyAbstract:In the case of a negative baseline Stress ratio, the fatigue crack growth rate can actually accelerate after a Tensile overload. This crack propagation behavior is related to the local bulging of the specimen in the thickness direction during compression and the resultant Tensile Residual Stress distribution at the crack tip. In the present investigation, the effects of a single Tensile overload as well as the effects of a Tensile overload followed immediately by a compressive underload on subsequent fatigue crack growth were investigated. The extent of crack opening displacement influences the magnitude of Residual Stress as well as the crack-tip opening level, and consequently, the subsequent rate of fatigue crack propagation.
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fatigue crack propagation in a Tensile Residual Stress field under a two step programmed test
International Journal of Fatigue, 1993Co-Authors: Akihiko Ohta, A J Mcevily, Naoyuki SuzukiAbstract:Abstract Fatigue crack propagation rates were measured under two-step programmed loading for a centre-cracked specimen of 9Cr-2Mo steel in which a high Tensile Residual Stress field had been previously induced. This Tensile Residual Stress makes the actual Stress ratio at the crack tip high enough to avoid crack closure. Therefore the applied range of Stress intensity factor ΔK coincided with the effective range ΔK eff , and as a result no transitional behaviour in the rate of fatigue crack propagation occurred after a sudden change in ΔK .
Akihiko Ohta - One of the best experts on this subject based on the ideXlab platform.
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Unique fatigue threshold and growth properties of welded joints in a Tensile Residual Stress field
International Journal of Fatigue, 1997Co-Authors: Akihiko Ohta, Naoyuki Suzuki, Yoshio MaedaAbstract:Abstract The fatigue threshold and high growth rate region properties were investigated on several kinds of welded joints. These properties became unique in spite of the variation of steels (ferrite-pearite, martensite, austenite), welding method, heat input and Stress ratio. It was revealed that the unique properties occurred from the fully opened fatigue crack due to the Tensile Residual Stresses. Based on these results, the equation of the fatigue crack growth curve for the design and inspection of welded structures was proposed. It is also suggested that the inducement of compressive Residual Stress at the fatigue critical zone is effective in improving the fatigue properties of welded structures.
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fatigue crack propagation in a Tensile Residual Stress field under a two step programmed test
International Journal of Fatigue, 1993Co-Authors: Akihiko Ohta, A J Mcevily, Naoyuki SuzukiAbstract:Abstract Fatigue crack propagation rates were measured under two-step programmed loading for a centre-cracked specimen of 9Cr-2Mo steel in which a high Tensile Residual Stress field had been previously induced. This Tensile Residual Stress makes the actual Stress ratio at the crack tip high enough to avoid crack closure. Therefore the applied range of Stress intensity factor ΔK coincided with the effective range ΔK eff , and as a result no transitional behaviour in the rate of fatigue crack propagation occurred after a sudden change in ΔK .
Weixing Chen - One of the best experts on this subject based on the ideXlab platform.
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the role of Residual Stress in neutral ph Stress corrosion cracking of pipeline steels part ii crack dormancy
Acta Materialia, 2007Co-Authors: Weixing Chen, G. Van Boven, R B RoggeAbstract:Abstract This investigation provides a quantitative analysis of the effect of Type I Residual Stresses on the occurrence of pitting and Stress corrosion cracking (SCC) formation in pipeline steel exposed to neutral pH aqueous environments. It has been shown that SCC generated in neutral pH environments can be readily blunted due to plastic deformation (room temperature creep) and/or extensive anodic dissolution. As a result, a high positive Tensile Residual Stress gradient is necessary for continued growth of SCC in pipeline steels exposed to this neutral pH environment. The Tensile Residual Stress represents a large mechanical driving force for crack nucleation and short crack growth. Active cracks may become dormant as the near-surface Residual Stress gradient changes, due to self-equilibration, from highly Tensile to a lower Tensile state or to a compressive state. The change in Residual Stress level can occur within 1 mm of the surface, resulting in a large proportion of dormant SCC.
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the role of Residual Stress in neutral ph Stress corrosion cracking of pipeline steels part i pitting and cracking occurrence
Acta Materialia, 2007Co-Authors: G. Van Boven, Weixing Chen, R B RoggeAbstract:Abstract In this investigation, Tensile test specimens were fabricated with increasing levels of compressive and Tensile Residual Stress on the surface and through the thickness of the specimen. These Residual Stresses were then measured by neutron diffraction at multiple points along the length and through the depth of the specimens. The specimens were then exposed to a neutral pH aqueous soil environment in combination with an applied cyclic Stress for various lengths of time in order to initiate and propagate Stress corrosion cracking (SCC). The formation of micro-pitting was found to occur preferentially in areas where the Tensile Residual Stresses were the highest (approximately 300 MPa), while SCC initiation occurred with a 71% normalized frequency in areas where the surface Residual Stress was in the range 150–200 MPa. The difference between Residual Stress levels occurring at SCC locations versus pitting locations resulted from both the change of Residual Stress during cyclic Stress application during SCC testing and the Residual Stress gradient in the depth direction.
