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Effect of zinc on strength and fatigue resistance of amalgam
Fatigue Abstracts Influence of lamellar lath orientation on the fatigue crack growth behavior of gamma base titanium aluminides. (;nanamoorthv, R., Mutoh, Y., Hayashi, K. atut Mizuhara, Y. ,S'eript Meto[I. M . n r . ([995) 33 (6~, 9(17-912 The fatigue crack growth of the lameflar microstructure materials (TiAI) strongly depend on the lamellar lath orientation. High resistance to crack growth was offered when the lamellar lath lay across the crack growth plane and the crack growth rate was higher when the crack passed through the interfaces. The lamellar lath at an angle to the crack plane produces high level of stress shielding colnpared with the lamellar lath parallel to the crack phme Graphs. micrographs, 12 rcf.
Fatigue and fracture behavior of aluminum-lithium alloys at ambient and cryogenic temperatures. Xu, YB.. Zhart,~, }.. IMmg. Z.G. ami He, Z.(,). Script Met.ll. Mater. (July 1995! 33 12), 179 183 The improved toughlress of AI Li alloys at cryogenic temperatures make them attraclive for low temperature applications. This has led to a study ol the fatigue properties of these alloys at cryogenic temperatures and the influence of Zr on these properties. Two AI-Li alloys were studied: Al-l.88Li-2.8"~Cu.22Mg-.02Zr and AI-2.30Li-2.88Cu-.23Mg-.17Zr. They were solution heat treated at 515<'(.', water quenched and aged 24 h at 165°C. Fatigue tests were conducted at 300 K and 77 K. All fractures exhibited some IG failure Thv data show thai ZI increases the room temperature fatigue strength, bnt the change in strength with increasing temperature is tess than with non-Zr alloys. Also. Zr additions result in less IG failure than no Zr additions. The o',erall effect of Zr on fatigue properties is positive with respect to fracture inode and strength, both al morn temperature and cryogenic temperatures. Graphs. micrographs, 12 rcf.
An inelastic multiple asperities model for the effects of compressive underloads in fatigue crack growth. Kard.mateas, (;.A and CarLson. R.L. Int. ,I. Frail. 11994 19951 70 (2), 99 116 conlnlon practice, the compressive {negative load ratio) excursions ale ignored when anal~.ses of fatigue crack growth in metals are condncted. However, reccnt cxperimental data ou fatigue crack growth with intemrittent compressive load excursions have shown that the use of this assumption leads in most cases to nonconservative predictkms. This paper presents a model that is capable of cxphuning the observed behavior, including the saturation of the compressive overload effects, and the increase in the crack growth rate once the initial, positi\e load ratio profile is resumed, following a compressive excursion. 3"he model is based on the plastic crushing of a single asperity ot multiple asperities located on the crack face close to the crack tip and under dominantly phme strain conditions. A comparison of the behavior for one and for two asperities is made. Moreover, the effects of hardness and ,,tram hardening arc als,~ CXalrlilled. As a
A fatigue analysis concept to avoid failure of forging tooling. Lange. K., Knoerr. M. and A/tan, T. Wire (1995) 3, 1(4 168 The causes of fatigue failure in cold forging tooling are discussed and a fatigue analysis concept that can he applied during process and tool design to estimate the tool life of a layout is presented. The concept was evaluated using the tool lile expermrents conducted at the Institute for Metal Forming at the University of Stuttgart. The tool life predictions compare favorabl? with the tool Ill) experienced in the experiments. Workpiece materials were M2 and D2 steels Graphs. 3 ref.
607
influences on fatigue behavior were the nrixcd microstructurc (particles and matrixL the nature of the crack tip. and creep. The superior resistance to tensile fatigue crack propagation of amalgams containing small amounts of Zn (approx 1 wt.%) in vitro compared with amalgams with no Zn correlated with the superior resistance to marginal breakdown m viv. of Zn-containing amalgams. The range of stress intensities over which stable cracks could propagate was small, while the large variations observed in fatigue crack growth rates lor individual materials invalidate predicting a unique fatigue liRz from the empirical equations obtained. Graphs. photomicrographs, mimerlms ref
Fatigue behavior of a single crystal nickel-base superallny. Ztumg, J.H., Xu, KB., Wang. Z.G. and H., Z.Q Script Metall. Mater. (19951 32 {121. 2(193-2098 Fracture characteristics and fracture mechanism m a nickel-based single crystal superalloy have been studied. The conrposition (wt.q-) of the superalloy was Ni- 15.6 ICr-8.40Co 5.74W 3.80AI-3.82Ti- I. 16Ta. Heat treated specimens were subjected to high cycle fatigue tests under load control at 800<'(` and 85 Hz. The high cycle fatigue strength obtained from the 5; N cur\e was 583 MPa. which is greater than the same reported for the alloys IN738 and DS38G. SEM fractographs show cleavage and tearing dimple modes of fracture, fhese further indicate that the fracture modes were associated with phmar slip. dislocation cell deformation, and fl~nnation ol low angle gndn boundaries. TEM images reveal that y'-morphology changed from cuboidal to spherical during high cycle fatigue. Graphs. photomicrographs. 6 rel.
High cycle fatigue life improvement of polyerystailine c~-iron modified by silver, chromium, aluminium and yttrium ion implantation. Wang. H.W., Y.ng, D.Z, Shi, W.D. and Patu, 5. Script Metal/. ,'Vlater. (1995) 32 t121, 2001 2007 Effect of metal ion mrplantation on the high latiguc cycle behavior of t~-iron was studied. Silver, chromium, yttrium and alunfinum were implanted in annealed polycrystallinc ot iron substrates by metallic evaporation ion Jnlplantation method. Specimens with and without ion imphmtatkm were sul~jected to high cycle fatigue test in stress amplitude control tension tenskm mode. Mean ferrite grain size in the substrate was 21.05 1~ m. It was flmnd from tile stress-cycle curves that endurance stress limited increased with silver km implantation, and within that. with higher implantation dosages. The percent increase in endurance stress limit was in the order AI+ > Y - ' ( ' l q - > A g + . II is suggested that fatigue properties of [t iron ilnprovt's on iou inlplalltation. Graphs. 23 rel.
A new fracture mechanics method to predict the fatigue life of welded cruciform joints. Guha, B. Eny,ng. Froct. Mech. (1995) 52 12). 215 -229 The fatigue lile of MIG welded crucifornr joint failing from root (LOP) region was succcssfnlly predicted using new fracture mechanics cquatkms. These equations were developed by combining Paris" law and AK~-endurancc equation and incorporating an integral factor (l~,l, obtained by integrating Paris" equation. In the numerical fommlation of the equation, the initiation life iN0 and propagation tile (NI,) of the joint were accounted lot to obtain the total lhtigue life IN0. The initiation life was obtained experimentally usilrg crack "initiation criteria'. The propagation life was evaluated using the uunrerically developed equations. The method outlined successfully predicted the fatigue life of the joint front its crack growth parameters. To test the accuracy of the method, the predicted data were compared with the experimental data. It was found that the predicted data compared quite well widl the experimental data. This method is simple and can be applied easily for other joint ~cometries Graphs,
] g rcf, Bending fatigue of locked coil ropes in the proximity of their ends. Ophaka. G. and Roth. M. Wire (1995) 3, I % 159 The ropes OI man3 suspension structures are exposed to oscillations which cause increased alternating bending stresses at their ends. The aim of the tests carried out was Io investigate how the alternating bending of a locked civil rope in the proximity of the cast socket affects its fatigue strength. In tire tests a single locked coil rope was used (diameter 31 ram. breaking strength 985 kN). The compound cast sockets were tested both with and without solt lined protective sleeves which were attached at different distances in front of them. Graphs, 3 rel.
Effect of zinc on strength and fatigue resistance of amalgam. Watkins, J.H.. Nakajima, H., Hanaoka, K., Zhao, L., lwamoto, T. and Okahe, 7~ Dent. Mater. l January 1995) II (IL 24-33 This study was conducted to determine the effect of zinc in amalgam on the static mechanic properties and resistance to fatigue-crack propagation of amalgams. Fatigue, creep, compressive and flexure tests were performed on highCu Disperalloy (Johnson and Johnson Dental Products Go., East Windsor, New Jersey, USA) anti low Cu Velvalloy (S.S. White Dental Products Int., Philadelphia. Pennsylvania. USA) in both Zn-containing and Zn-free formulations. Linear elastic fiacture mechanics principles were used to characterize the fatigue behavior (crack lengths were monitored). The incorporation of Zn into these amalgams significantly improved their fatigue and creep resistance, while the effect of Zu on the static compressive and flexure strengths was not consistent. Zinc significantly increased (p < 0.05) the resistance to fatigue crack propagation during Stage II crack growth for both amalgams, and increased the variations in crack velocity for a given stress intensity difference. without visibly altering the path or nature of the fatigue cracks. Possible
Fatigue design data and concepts of aluminum structures. I. Tukeuehi, K. J. Jpn. Inst. Light Met. (1995) 33 IlL 3 6 q 5 Aluminum alloy high cycle |htiguc test is the fl.~cal point of discussion particularly as the axle load S-N data with some arrangement of Iomign papers' data for a fatigue design approach by the author. ]=Ol example the stress forms of a 2.8 ton car made fl'om AI alloy Irame are [)lotted at 20 60 km h ~ velocity using strain gauges. The amplitude is not constant and the tests show that varying stress, repeated, or urultiple stress conditions occur. These terminologies are explained as related to the case study in mathematical terms. The above stresses also include pulsating, reversed and partly reversed stress. The S N graph for 7Nfil-75 alloy 5 into thick extrusion joint used in the car. is shown with fatigue strength at N cycles endurance limit followed by P-S-N determination method (Log S, Log N. etch plotted for above and 7003-T5 alloy 6 tuna extruded specimen. Graphs. I I ref.
Fatigue design data and concepts of aluminum structures. I1. ?akeuchi, K. Kei Kinmku '/osetmt (J. Light Met. Wehl. ('on~tr.) t l905) 33 (2l, 24 37 Constant lifetime and endurance fatigue diagrams are normally used for aluminum structure design evaluatkm. There are four types of diagram methods traditionally being used in conjunction with structures. These are Haigh, Smith, Ros and Moo~Kommers-Japser diagrams as described in detail and illustrated. The correlation between yield point and the true fracture stress in the axial load fatigue test is developed and plotted. At the Japan Society of Mechanical Engineering, the average steel stress data in case of fatigue, etc. are gathered in an organized form [or the users. For those data that include average stress, the fatigue limit does increase, therefore the tensile average ahme is adequate
Fatigue and fracture behavior of aluminum-lithium alloys at ambient and cryogenic temperatures. Xu, YB.. Zhart,~, }.. IMmg. Z.G. ami He, Z.(,). Script Met.ll. Mater. (July 1995! 33 12), 179 183 The improved toughlress of AI Li alloys at cryogenic temperatures make them attraclive for low temperature applications. This has led to a study ol the fatigue properties of these alloys at cryogenic temperatures and the influence of Zr on these properties. Two AI-Li alloys were studied: Al-l.88Li-2.8"~Cu.22Mg-.02Zr and AI-2.30Li-2.88Cu-.23Mg-.17Zr. They were solution heat treated at 515<'(.', water quenched and aged 24 h at 165°C. Fatigue tests were conducted at 300 K and 77 K. All fractures exhibited some IG failure Thv data show thai ZI increases the room temperature fatigue strength, bnt the change in strength with increasing temperature is tess than with non-Zr alloys. Also. Zr additions result in less IG failure than no Zr additions. The o',erall effect of Zr on fatigue properties is positive with respect to fracture inode and strength, both al morn temperature and cryogenic temperatures. Graphs. micrographs, 12 rcf.
An inelastic multiple asperities model for the effects of compressive underloads in fatigue crack growth. Kard.mateas, (;.A and CarLson. R.L. Int. ,I. Frail. 11994 19951 70 (2), 99 116 conlnlon practice, the compressive {negative load ratio) excursions ale ignored when anal~.ses of fatigue crack growth in metals are condncted. However, reccnt cxperimental data ou fatigue crack growth with intemrittent compressive load excursions have shown that the use of this assumption leads in most cases to nonconservative predictkms. This paper presents a model that is capable of cxphuning the observed behavior, including the saturation of the compressive overload effects, and the increase in the crack growth rate once the initial, positi\e load ratio profile is resumed, following a compressive excursion. 3"he model is based on the plastic crushing of a single asperity ot multiple asperities located on the crack face close to the crack tip and under dominantly phme strain conditions. A comparison of the behavior for one and for two asperities is made. Moreover, the effects of hardness and ,,tram hardening arc als,~ CXalrlilled. As a
A fatigue analysis concept to avoid failure of forging tooling. Lange. K., Knoerr. M. and A/tan, T. Wire (1995) 3, 1(4 168 The causes of fatigue failure in cold forging tooling are discussed and a fatigue analysis concept that can he applied during process and tool design to estimate the tool life of a layout is presented. The concept was evaluated using the tool lile expermrents conducted at the Institute for Metal Forming at the University of Stuttgart. The tool life predictions compare favorabl? with the tool Ill) experienced in the experiments. Workpiece materials were M2 and D2 steels Graphs. 3 ref.
607
influences on fatigue behavior were the nrixcd microstructurc (particles and matrixL the nature of the crack tip. and creep. The superior resistance to tensile fatigue crack propagation of amalgams containing small amounts of Zn (approx 1 wt.%) in vitro compared with amalgams with no Zn correlated with the superior resistance to marginal breakdown m viv. of Zn-containing amalgams. The range of stress intensities over which stable cracks could propagate was small, while the large variations observed in fatigue crack growth rates lor individual materials invalidate predicting a unique fatigue liRz from the empirical equations obtained. Graphs. photomicrographs, mimerlms ref
Fatigue behavior of a single crystal nickel-base superallny. Ztumg, J.H., Xu, KB., Wang. Z.G. and H., Z.Q Script Metall. Mater. (19951 32 {121. 2(193-2098 Fracture characteristics and fracture mechanism m a nickel-based single crystal superalloy have been studied. The conrposition (wt.q-) of the superalloy was Ni- 15.6 ICr-8.40Co 5.74W 3.80AI-3.82Ti- I. 16Ta. Heat treated specimens were subjected to high cycle fatigue tests under load control at 800<'(` and 85 Hz. The high cycle fatigue strength obtained from the 5; N cur\e was 583 MPa. which is greater than the same reported for the alloys IN738 and DS38G. SEM fractographs show cleavage and tearing dimple modes of fracture, fhese further indicate that the fracture modes were associated with phmar slip. dislocation cell deformation, and fl~nnation ol low angle gndn boundaries. TEM images reveal that y'-morphology changed from cuboidal to spherical during high cycle fatigue. Graphs. photomicrographs. 6 rel.
High cycle fatigue life improvement of polyerystailine c~-iron modified by silver, chromium, aluminium and yttrium ion implantation. Wang. H.W., Y.ng, D.Z, Shi, W.D. and Patu, 5. Script Metal/. ,'Vlater. (1995) 32 t121, 2001 2007 Effect of metal ion mrplantation on the high latiguc cycle behavior of t~-iron was studied. Silver, chromium, yttrium and alunfinum were implanted in annealed polycrystallinc ot iron substrates by metallic evaporation ion Jnlplantation method. Specimens with and without ion imphmtatkm were sul~jected to high cycle fatigue test in stress amplitude control tension tenskm mode. Mean ferrite grain size in the substrate was 21.05 1~ m. It was flmnd from tile stress-cycle curves that endurance stress limited increased with silver km implantation, and within that. with higher implantation dosages. The percent increase in endurance stress limit was in the order AI+ > Y - ' ( ' l q - > A g + . II is suggested that fatigue properties of [t iron ilnprovt's on iou inlplalltation. Graphs. 23 rel.
A new fracture mechanics method to predict the fatigue life of welded cruciform joints. Guha, B. Eny,ng. Froct. Mech. (1995) 52 12). 215 -229 The fatigue lile of MIG welded crucifornr joint failing from root (LOP) region was succcssfnlly predicted using new fracture mechanics cquatkms. These equations were developed by combining Paris" law and AK~-endurancc equation and incorporating an integral factor (l~,l, obtained by integrating Paris" equation. In the numerical fommlation of the equation, the initiation life iN0 and propagation tile (NI,) of the joint were accounted lot to obtain the total lhtigue life IN0. The initiation life was obtained experimentally usilrg crack "initiation criteria'. The propagation life was evaluated using the uunrerically developed equations. The method outlined successfully predicted the fatigue life of the joint front its crack growth parameters. To test the accuracy of the method, the predicted data were compared with the experimental data. It was found that the predicted data compared quite well widl the experimental data. This method is simple and can be applied easily for other joint ~cometries Graphs,
] g rcf, Bending fatigue of locked coil ropes in the proximity of their ends. Ophaka. G. and Roth. M. Wire (1995) 3, I % 159 The ropes OI man3 suspension structures are exposed to oscillations which cause increased alternating bending stresses at their ends. The aim of the tests carried out was Io investigate how the alternating bending of a locked civil rope in the proximity of the cast socket affects its fatigue strength. In tire tests a single locked coil rope was used (diameter 31 ram. breaking strength 985 kN). The compound cast sockets were tested both with and without solt lined protective sleeves which were attached at different distances in front of them. Graphs, 3 rel.
Effect of zinc on strength and fatigue resistance of amalgam. Watkins, J.H.. Nakajima, H., Hanaoka, K., Zhao, L., lwamoto, T. and Okahe, 7~ Dent. Mater. l January 1995) II (IL 24-33 This study was conducted to determine the effect of zinc in amalgam on the static mechanic properties and resistance to fatigue-crack propagation of amalgams. Fatigue, creep, compressive and flexure tests were performed on highCu Disperalloy (Johnson and Johnson Dental Products Go., East Windsor, New Jersey, USA) anti low Cu Velvalloy (S.S. White Dental Products Int., Philadelphia. Pennsylvania. USA) in both Zn-containing and Zn-free formulations. Linear elastic fiacture mechanics principles were used to characterize the fatigue behavior (crack lengths were monitored). The incorporation of Zn into these amalgams significantly improved their fatigue and creep resistance, while the effect of Zu on the static compressive and flexure strengths was not consistent. Zinc significantly increased (p < 0.05) the resistance to fatigue crack propagation during Stage II crack growth for both amalgams, and increased the variations in crack velocity for a given stress intensity difference. without visibly altering the path or nature of the fatigue cracks. Possible
Fatigue design data and concepts of aluminum structures. I. Tukeuehi, K. J. Jpn. Inst. Light Met. (1995) 33 IlL 3 6 q 5 Aluminum alloy high cycle |htiguc test is the fl.~cal point of discussion particularly as the axle load S-N data with some arrangement of Iomign papers' data for a fatigue design approach by the author. ]=Ol example the stress forms of a 2.8 ton car made fl'om AI alloy Irame are [)lotted at 20 60 km h ~ velocity using strain gauges. The amplitude is not constant and the tests show that varying stress, repeated, or urultiple stress conditions occur. These terminologies are explained as related to the case study in mathematical terms. The above stresses also include pulsating, reversed and partly reversed stress. The S N graph for 7Nfil-75 alloy 5 into thick extrusion joint used in the car. is shown with fatigue strength at N cycles endurance limit followed by P-S-N determination method (Log S, Log N. etch plotted for above and 7003-T5 alloy 6 tuna extruded specimen. Graphs. I I ref.
Fatigue design data and concepts of aluminum structures. I1. ?akeuchi, K. Kei Kinmku '/osetmt (J. Light Met. Wehl. ('on~tr.) t l905) 33 (2l, 24 37 Constant lifetime and endurance fatigue diagrams are normally used for aluminum structure design evaluatkm. There are four types of diagram methods traditionally being used in conjunction with structures. These are Haigh, Smith, Ros and Moo~Kommers-Japser diagrams as described in detail and illustrated. The correlation between yield point and the true fracture stress in the axial load fatigue test is developed and plotted. At the Japan Society of Mechanical Engineering, the average steel stress data in case of fatigue, etc. are gathered in an organized form [or the users. For those data that include average stress, the fatigue limit does increase, therefore the tensile average ahme is adequate