{"title":"Cyclic Flexural Behavior of Steel Pipes Repaired by Patch Plate Subjected to Constant Axial Force","authors":"Kazuo Furunishi, Y. Kitane, Y. Itoh","doi":"10.2472/JSMS.61.543","DOIUrl":"https://doi.org/10.2472/JSMS.61.543","url":null,"abstract":"","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73602610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Sakaiya, Mitsuru Takahashi, T. Sakakibara, T. Noguchi
This thesis describes the effect of ground improvement due to Low-Replacement-Ratio SCP Method. In this method, the replacement ratio is 30 to 50 percent. Because 70 percent of the consolidation layer is composed of unimproved clay, it is designed with taking account of increase in strength of clay. Therefore, it is required to grasp strength of clay between the improved piles accurately which enables to compare the stress sharing of sand and clay. In addition, the factor of safety against slip failure can be obtained. This thesis studies a case about measurement of circular slide and stress sharing ratio by strength and void ratio of clay measured with RI-CPT and its analysis flow. The case is Haneda Air Port D-RUNWAY Project.
{"title":"Improvement Effect Evaluation of Low-Replacement-Ratio SCP Method with RI-CPT","authors":"T. Sakaiya, Mitsuru Takahashi, T. Sakakibara, T. Noguchi","doi":"10.2472/JSMS.61.68","DOIUrl":"https://doi.org/10.2472/JSMS.61.68","url":null,"abstract":"This thesis describes the effect of ground improvement due to Low-Replacement-Ratio SCP Method. In this method, the replacement ratio is 30 to 50 percent. Because 70 percent of the consolidation layer is composed of unimproved clay, it is designed with taking account of increase in strength of clay. Therefore, it is required to grasp strength of clay between the improved piles accurately which enables to compare the stress sharing of sand and clay. In addition, the factor of safety against slip failure can be obtained. This thesis studies a case about measurement of circular slide and stress sharing ratio by strength and void ratio of clay measured with RI-CPT and its analysis flow. The case is Haneda Air Port D-RUNWAY Project.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82217672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zirconia/SiC composite ceramics have a high crack-healing ability at low temperature. We investigated the effects of SiC composite, environment on the crack-healing behavior. We also investigated the fatigue strength of heat-treated specimens. The main conclusions are as follows : (1) For crack-healing of ZrO2 ceramics it is necessary both a composite SiC and an oxidation environment. (2) When ZrO2/SiC ceramics are heat-treated in air, a phase-transformation by SiC composite caused not only the crack- healing but improvement of the fracture toughness and bending strength.
{"title":"Crack-Healing Behaviour of Zirconia /SiC Composite Ceramics and Strength Properties of Crack-Healing Specimens","authors":"K. Houjou, Syunsuke Sudo, Koji Takahashi","doi":"10.2472/JSMS.60.742","DOIUrl":"https://doi.org/10.2472/JSMS.60.742","url":null,"abstract":"Zirconia/SiC composite ceramics have a high crack-healing ability at low temperature. We investigated the effects of SiC composite, environment on the crack-healing behavior. We also investigated the fatigue strength of heat-treated specimens. The main conclusions are as follows : (1) For crack-healing of ZrO2 ceramics it is necessary both a composite SiC and an oxidation environment. (2) When ZrO2/SiC ceramics are heat-treated in air, a phase-transformation by SiC composite caused not only the crack- healing but improvement of the fracture toughness and bending strength.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81578498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Miyashita, K. Takeda, S. Ohya, Y. Sano, Toshiyuki Saito, K. Akita
The relaxation behavior of residual stress induced by laser peening during mechanical loading was investigated on an aluminum alloy A2024. The residual stress relaxation process was measured by x-ray diffraction method and analyzed by a finite element method (FEM). The plastic deformation behavior was evaluated from the x-ray diffraction peak width and the FEM. The surface residual stress relaxation under tensile loading occurred when the plastic-deformation started at the inside of material where the balancing tensile residual stress existed. Under the compressive loading, the surface residual stress relaxation started due to the plastic deformation beneath the surface where the maximum compressive residual stress existed. The plastic deformation at the inside of material caused the redistribution of the residual stress and resulted in the relaxation of the surface residual stress. For both tensile and compressive loading, the surface compressive residual stress relaxation occurred before the total stress ( = (residual stress) + (applied stress)) at the surface reached the yield condition. All discussions in this study based on the mechanical deformation behaviour of the material. Therefore, the conclusions of this study are thought to be able to apply to the behavior of the residual stress under the mechanical loading on metallic materials treated by any mechanical surface treatment.
{"title":"Relaxation Behaviour of Laser Peening Residual Stress due to Mechanical Loading on Aluminum Alloy","authors":"D. Miyashita, K. Takeda, S. Ohya, Y. Sano, Toshiyuki Saito, K. Akita","doi":"10.2472/JSMS.60.617","DOIUrl":"https://doi.org/10.2472/JSMS.60.617","url":null,"abstract":"The relaxation behavior of residual stress induced by laser peening during mechanical loading was investigated on an aluminum alloy A2024. The residual stress relaxation process was measured by x-ray diffraction method and analyzed by a finite element method (FEM). The plastic deformation behavior was evaluated from the x-ray diffraction peak width and the FEM. The surface residual stress relaxation under tensile loading occurred when the plastic-deformation started at the inside of material where the balancing tensile residual stress existed. Under the compressive loading, the surface residual stress relaxation started due to the plastic deformation beneath the surface where the maximum compressive residual stress existed. The plastic deformation at the inside of material caused the redistribution of the residual stress and resulted in the relaxation of the surface residual stress. For both tensile and compressive loading, the surface compressive residual stress relaxation occurred before the total stress ( = (residual stress) + (applied stress)) at the surface reached the yield condition. All discussions in this study based on the mechanical deformation behaviour of the material. Therefore, the conclusions of this study are thought to be able to apply to the behavior of the residual stress under the mechanical loading on metallic materials treated by any mechanical surface treatment.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88042165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Douglas fir wood flour was liquefied in the presence of phenol/catalytic amounts of sulfuric acid mixture, after which formalin was added and reacted. Then, the free phenol was distilled off under reduced pressure from the reaction mixture to obtain the liquefied and resinified wood. The liquefied and resinified wood was melt spun, stabilized by three dimensional curing and finally carbonized at 900°C. Carbon fiber made from liquefied wood without reaction with formaldehyde resulted in the formation of macropores in it, which were found by SEM observations. The resinification of the liquefied wood with adequate amounts of formaldehyde prevented the formation of the macropores, which was endorsed by carbonization of synthetic novolak fibers. Measurements of carbonization yield by TGA comes into line with these observations.
{"title":"Fabrication and Characterization of Carbon Fiber Derived from Woody Biomass","authors":"M. Yoshioka, H. Katsura, N. Shiraishi","doi":"10.2472/JSMS.60.35","DOIUrl":"https://doi.org/10.2472/JSMS.60.35","url":null,"abstract":"Douglas fir wood flour was liquefied in the presence of phenol/catalytic amounts of sulfuric acid mixture, after which formalin was added and reacted. Then, the free phenol was distilled off under reduced pressure from the reaction mixture to obtain the liquefied and resinified wood. The liquefied and resinified wood was melt spun, stabilized by three dimensional curing and finally carbonized at 900°C. Carbon fiber made from liquefied wood without reaction with formaldehyde resulted in the formation of macropores in it, which were found by SEM observations. The resinification of the liquefied wood with adequate amounts of formaldehyde prevented the formation of the macropores, which was endorsed by carbonization of synthetic novolak fibers. Measurements of carbonization yield by TGA comes into line with these observations.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89207982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Ebara, K. Takeda, M. Iwamoto, Hideaki Fujimoto, A. Ogura, S. Hamaya
Microfractographic features in fracture surfaces for tensile, fatigue, impact, three point bending specimens of cold forging die steels with Rockwell C scale hardness number of 52 to 68 are presented. The emphasis is placed upon the stretched zone formation ahead of the fatigue crack and the relation between the stretched zone width and fracture toughness. Fatigue crack initiation behavior of plane and notched specimens are also characterized in low cycle up to giga-cycle ranges. A couple of microfractographic analyzed results for failed actual cold forging dies are exemplified. It can be concluded that qualitative and quantitative analysis by use of microfractograpy are possible for cold forging die failures.
{"title":"The Role of Microfractography in Failure Analysis of Cold Forging Dies","authors":"R. Ebara, K. Takeda, M. Iwamoto, Hideaki Fujimoto, A. Ogura, S. Hamaya","doi":"10.2472/JSMS.60.1009","DOIUrl":"https://doi.org/10.2472/JSMS.60.1009","url":null,"abstract":"Microfractographic features in fracture surfaces for tensile, fatigue, impact, three point bending specimens of cold forging die steels with Rockwell C scale hardness number of 52 to 68 are presented. The emphasis is placed upon the stretched zone formation ahead of the fatigue crack and the relation between the stretched zone width and fracture toughness. Fatigue crack initiation behavior of plane and notched specimens are also characterized in low cycle up to giga-cycle ranges. A couple of microfractographic analyzed results for failed actual cold forging dies are exemplified. It can be concluded that qualitative and quantitative analysis by use of microfractograpy are possible for cold forging die failures.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85388487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The global warming is one of the most important problems for many countries. It is necessary to use fly ash instead of cement to decrease CO2 emission. This study shows influence of curing conditions in early-age on the pore structure of concrete with fly ash. The microstructure of dried concrete can be divided into 2 parts, if the volume of macro pore having larger than 50nm diameter and mode pore diameter are considered. One is porous microstructure because of drying. The other is the microstructure of concrete in which the hydration continues even after finishing moist curing. When the concrete blended fly ash in 15% of binder is cured in moisture for 7days, fly ash reacts effectively and the depth of parts influenced by drying is the same as that of concrete used only cement. If the mixture includes fly ash in 30% of binder and it is cured in moisture for 3 or 7 days, the microstructure is more porous than the other mixture. When the concrete is cured in moisture for 28 days, all microstructures have almost the same pore structures. Carbonation of dried concrete is also focused on in this study. Then, it evaluates the contribution of fly ash as a binder to carbonation rate with k-value. As fly ash fraction increases, carbonation depth becomes larger. However, when fly ash fraction is 15% and the concrete is cured in moisture for 7 days, the carbonation depth is almost the same as that of concrete used only cement. If fly ash is used in this condition, k-value shows 0.4 and k'-value, which is in the case of considering inhomogeneous of structure, shows the almost 1.0. The fly ash could be used as a general material if the fraction is 15% and the period of the moist-curing is 7days.
{"title":"Influence of Curing in Early-Age and Drying to Microstructure of Fly Ash Concrete","authors":"Y. Ogawa, K. Uji, A. Ueno","doi":"10.2472/JSMS.60.763","DOIUrl":"https://doi.org/10.2472/JSMS.60.763","url":null,"abstract":"The global warming is one of the most important problems for many countries. It is necessary to use fly ash instead of cement to decrease CO2 emission. This study shows influence of curing conditions in early-age on the pore structure of concrete with fly ash. The microstructure of dried concrete can be divided into 2 parts, if the volume of macro pore having larger than 50nm diameter and mode pore diameter are considered. One is porous microstructure because of drying. The other is the microstructure of concrete in which the hydration continues even after finishing moist curing. When the concrete blended fly ash in 15% of binder is cured in moisture for 7days, fly ash reacts effectively and the depth of parts influenced by drying is the same as that of concrete used only cement. If the mixture includes fly ash in 30% of binder and it is cured in moisture for 3 or 7 days, the microstructure is more porous than the other mixture. When the concrete is cured in moisture for 28 days, all microstructures have almost the same pore structures. Carbonation of dried concrete is also focused on in this study. Then, it evaluates the contribution of fly ash as a binder to carbonation rate with k-value. As fly ash fraction increases, carbonation depth becomes larger. However, when fly ash fraction is 15% and the concrete is cured in moisture for 7 days, the carbonation depth is almost the same as that of concrete used only cement. If fly ash is used in this condition, k-value shows 0.4 and k'-value, which is in the case of considering inhomogeneous of structure, shows the almost 1.0. The fly ash could be used as a general material if the fraction is 15% and the period of the moist-curing is 7days.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86392067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Chiang, Noriaki Nishioka, Jian-yih Wang, H. Hosokawa, T. Uesugi, Y. Takigawa, K. Higashi
The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and a superplastic IN9021 alloy were measured by ring-compression tests in a temperature range from 573 to 753K and a stain rate range from 1.0 × 10-2 to 4.0 × 100s-1. In general the friction coefficients (m values) increase slightly with increasing the compressive strains even under the well-lubricated test conditions. The m values of the Al-Cu based alloys, including A2014, A2024 and IN9021, were almost same at 0.2∼0.4 at the temperatures below 723K, but increased rapidly at the temperatures above 723K. On the other hand those of A6061 were almost constant at about 0.4 at the temperatures below 753K. The analysis based on the constitutive equation with consideration of the effect from an existence of the particles indicated that the dominant deformation mechanisms under the investigated conditions were dislocation creep for A2014, and were superplasticity for IN9021 except for the test condition at 573K with 1.0 × 10-1s-1. The m values of the IN9021 were lower than those of A2014, even if the flow stresses of IN9021 were higher than those of A2014. So it was concluded that the m value under a superplasticity region was lower than that under a dislocation creep region. It suggested that the superplastic forming had more benefits for the engineering applications.
{"title":"Determination of Dynamic Friction Coefficients of Aluminum Alloys at Elevated Temperatures by Using Ring-Compression Tests","authors":"L. Chiang, Noriaki Nishioka, Jian-yih Wang, H. Hosokawa, T. Uesugi, Y. Takigawa, K. Higashi","doi":"10.2472/JSMS.60.838","DOIUrl":"https://doi.org/10.2472/JSMS.60.838","url":null,"abstract":"The dynamic friction coefficients of the commercial aluminum alloys (A2014, A2024 and A6061) and a superplastic IN9021 alloy were measured by ring-compression tests in a temperature range from 573 to 753K and a stain rate range from 1.0 × 10-2 to 4.0 × 100s-1. In general the friction coefficients (m values) increase slightly with increasing the compressive strains even under the well-lubricated test conditions. The m values of the Al-Cu based alloys, including A2014, A2024 and IN9021, were almost same at 0.2∼0.4 at the temperatures below 723K, but increased rapidly at the temperatures above 723K. On the other hand those of A6061 were almost constant at about 0.4 at the temperatures below 753K. The analysis based on the constitutive equation with consideration of the effect from an existence of the particles indicated that the dominant deformation mechanisms under the investigated conditions were dislocation creep for A2014, and were superplasticity for IN9021 except for the test condition at 573K with 1.0 × 10-1s-1. The m values of the IN9021 were lower than those of A2014, even if the flow stresses of IN9021 were higher than those of A2014. So it was concluded that the m value under a superplasticity region was lower than that under a dislocation creep region. It suggested that the superplastic forming had more benefits for the engineering applications.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88184455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Hayashi, Y. Morii, Toru Saito, H. Suzuki, A. Moriai
Residual stress distribution at the cylinder block wall in 1500cc class aluminum engine was measured using RESA in JRR-3 of JAEA. In order to increase neutron flux at the gauge volume measured, newly developed vertically focused collimator was employed. Since the grain size in cast aluminum engine block was large, the oscillation method was applied. The residual stresses near the surface layers of cylinder block wall were compressive all in the tangential, the thickness and the cylinder axial directions, but tensile in the middle part of cylinder block wall. This means the residual stress distributions are likely to be hydrostatic. The residual stresses in the tangential direction were not balanced in the cylinder block wall. If the residual stress distribution in the hoop direction is approximated by 2 dimensional power equation, the residual stresses on the cylinder wall surface is estimated as about -140MPa and the mean residual stress in the cylinder wall is 15MPa.
{"title":"Residual Stress Measurement in Aluminum Engine Block","authors":"M. Hayashi, Y. Morii, Toru Saito, H. Suzuki, A. Moriai","doi":"10.2472/JSMS.60.624","DOIUrl":"https://doi.org/10.2472/JSMS.60.624","url":null,"abstract":"Residual stress distribution at the cylinder block wall in 1500cc class aluminum engine was measured using RESA in JRR-3 of JAEA. In order to increase neutron flux at the gauge volume measured, newly developed vertically focused collimator was employed. Since the grain size in cast aluminum engine block was large, the oscillation method was applied. The residual stresses near the surface layers of cylinder block wall were compressive all in the tangential, the thickness and the cylinder axial directions, but tensile in the middle part of cylinder block wall. This means the residual stress distributions are likely to be hydrostatic. The residual stresses in the tangential direction were not balanced in the cylinder block wall. If the residual stress distribution in the hoop direction is approximated by 2 dimensional power equation, the residual stresses on the cylinder wall surface is estimated as about -140MPa and the mean residual stress in the cylinder wall is 15MPa.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79938306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Kariya, N. Kawagoishi, S. Furumoto, Yuzo Nakamura, E. Kondo
In order to investigate the effects of aging structures and humidity on fatigue properties of an extruded bar of age-hardened Al alloy 7075, rotating bending fatigue tests were carried out on T62, T73 and RRA (retrogression and reaging) treated plain specimens in two relative humidity of 25% and 85%. Fatigue strength in low humidity was higher in the order of the RRA, T62 and T73 treated specimens corresponding to the order of static strength. On the other hand, fatigue strength decreased in high humidity in all of the alloys and the decrease was the highest in the RRA treated specimen, which means that the RRA treated alloy is very sensitive to humidity environment. In case of the T73 treated alloy, cracks propagated in shear mode in high humidity and under high stress levels due to the marked texture of the alloy, though tensile mode crack growth is more common in the alloy. Similar crack growth behavior was found in the T62 treated alloy, too. In case of the RRA treated alloy, however, the tendency for a crack to grow in the shear mode was very weak even in high humidity and under high stress levels in spite that the alloy had the same marked texture. The effects of microstructure and humidity on the initiation and propagation of small cracks were marked in all of the alloys.
{"title":"Effects of Aging Structures and Humidity on Fatigue Properties of Age-Hardened Al Alloy","authors":"K. Kariya, N. Kawagoishi, S. Furumoto, Yuzo Nakamura, E. Kondo","doi":"10.2472/JSMS.60.1015","DOIUrl":"https://doi.org/10.2472/JSMS.60.1015","url":null,"abstract":"In order to investigate the effects of aging structures and humidity on fatigue properties of an extruded bar of age-hardened Al alloy 7075, rotating bending fatigue tests were carried out on T62, T73 and RRA (retrogression and reaging) treated plain specimens in two relative humidity of 25% and 85%. Fatigue strength in low humidity was higher in the order of the RRA, T62 and T73 treated specimens corresponding to the order of static strength. On the other hand, fatigue strength decreased in high humidity in all of the alloys and the decrease was the highest in the RRA treated specimen, which means that the RRA treated alloy is very sensitive to humidity environment. In case of the T73 treated alloy, cracks propagated in shear mode in high humidity and under high stress levels due to the marked texture of the alloy, though tensile mode crack growth is more common in the alloy. Similar crack growth behavior was found in the T62 treated alloy, too. In case of the RRA treated alloy, however, the tendency for a crack to grow in the shear mode was very weak even in high humidity and under high stress levels in spite that the alloy had the same marked texture. The effects of microstructure and humidity on the initiation and propagation of small cracks were marked in all of the alloys.","PeriodicalId":17366,"journal":{"name":"journal of the Japan Society for Testing Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76656921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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