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Statistical analysis of high cycle fatigue crack growth: centre crack in aluminum panel
Fatigue Abstracts
733
least squares analysis to estimate FL. FL (MPa) = 10.4 × d ~:2+ 51 × (%Si) + 16 × (%Mn) + 80. Graphs, photomicrographs, 34 ref.
Statistical analysis of high cycle fatigue crack growth: centre crack in aluminum panel. Huang, Y.C. and Z~u, P.C. Theoretical and Appl. Fracture Mech. (I Apr. 1996) 25 (I), 59 64
Corrosion resistance and corrosion fatigue strength of new titanium alloys for medical implants without V and Al. Okazaki, Y., lto, Y. Kyo. K. and 7~aeishi, 7" Mater. Sci. Eng. A (15 Aug. 1996) 213(I-2), 138-147
High cycle latigue crack growth results are obtained from a statistical analysis and compared with test data for an aluminium panel with a centre crack under constant amplitude cyclic load. The analysis makes use of a generalized FockPlanck equation that is satisfied by a union probabilistic density of stochastic variables of cycle number and crack length. Obtained are high degrees of modified expressions of the equation's coefficients and hence the analytical solution. A two-parameter fatigue crack growth rate relation is assumed together with a logarithmic average life distribution. Good agreement is obtained with test data for different initial crack lengths.
"['he corrosion resistance and the corrosion fatigue strength of Ti-15Zr~[Nb 4Ta 0.2Pd-0.20-0.05N and Ti-15Sn-4Nb-2Ta~0.2Pd 0.20 alloys were compared with those of Ti-6AI~4 V extra low interstitial (ELI), Ti-6AI-2Nb-ITa, pure Ti grade 2 and [3 type Ti-15C/cMo-5Zr-3AI alloys. Anodic polarization and corrosion fatigue testings were performed in various physiological saline solutions at 31(IK The corrosion fatigue test was carried out under the condition of a tension to tension mode with a sine wave at a stress ratio of 0.1 and at a frequency of 10 Hz. The tensile properties of these alloys were measured at room temperature. The change in current density was small up to passivity zone in I wt% lactic acid. P B S ( ) , calf serum and eagle's MEM+tetal bovine serum solutions except 5 wt% HCh The current density of Ti 15Zr~Nb~.Ta-0.2Pd-0.20-0.05N alloy at potential up to 5 V tend to be lower than that of Ti-6AI~J.V ELI. Otherwise passive current density of the [3 type Ti-15Mo-5Zr-3AI alloy was higher than that of o~ + [3 type alloys. The passive fihns formed on Ti-15Zr-4Nb-4Ta~).2Pd-0.20 alloy in the calf serum consisted mainly of TiO> ZrO,, NbeOs, Ta205 and Pd or PdO as demonstrated using X-ray photoelectron spectroscopy. The cycle to failure of Ti 15Zr~-Nb~ITa~I.2Pd-0.20-0.05N and Ti-15Sn-4Nb-4Ta~).2Pd~0.20 alloys annealed at 973 K for 7.2 ks increased with decreasing applied maximum stress. The fatigue strength at l0 s cycles in those alloys was about 600 MPa. The fatigue strength of Ti 6AI 2Nb ITa alloy at 10~ cycles was about 700 MPa. The fatigue strength of [3 type Ti-I 5Mo-5Zr-3AI alloy at 107 cycles was lower than that of ¢~ + [3 type alloys.
The microstructure dependence of fatigue behaviour in Ti-15Mo--5Zr3Al alloy. Tokaji. K.. Bian. J. C., Ogawa, T. and Naka]ima. M. Mater. Sei. Eng. A (1996) 213 (I 2), 86 92 In order to better understand the fundamental fatigue behaviour of a beta Ti 15Mo-5Z~3AI alloy, rotating bending fatigue tests have been carried out using materials with three different microstructures, that is, [3 grain sizes, which were solution treated at 735°C (STA735), 850°C (STA850), and 1000°C (STAI000) followed by aging at 500°C. It was found that STA735 showed the highest fatigue strength while the materials solution treated above the beta transus, STA850 and STAI(X)0, had fatigue lives which decreased with increasing solution treatment temperature, that is, [3 grain size. There was no significant difference in fatigue limit between the materials. Fatigue cracks were initiated as a result of cyclic slip deformation in STA735, but the crack initiation site was related to [3 groin boundaries in both STAB50 and STAI000. In particular, STA850 exhibited an unique initiation behaviour in which cracks were initiated on the specimen surface at higher stress levels, but subsurface crack initiation was observed at lower stress levels. Since STA735 indicated considerably slower crack initiation than STA850 and STA1000 and the growth rates of small cracks were almost the same for all the materials, the excellent fatigue strength of STA735 was primarily attributed to higher crack initiation resistance of its microstrncture.
Effect of heat treatment on fatigue crack growth rate of Inconel 690 and Inconel 600. Park. H.-B.. Kinl, }'%H.. Lee, B.-W. and Rheem. K.-S. J. Nuel. Mat. (1996) 231 (3), 204 212 The effects of heat treatment on fatigue crack growth rates (FCGRs) of lnconel 690 and Inconel 600 have been investigated in terms of carbide morphology and grain size. Cycling tests in air at room temperature have shown that FCGR in low stress intensity factor range (AK) region can be effectively reduced by increasing the grain boundary carbide precipitate size and grain size. Decrease in FCGR is attributed to the crack tip blunting at the precipitates of grain boundary chromium carbides. Compared with test data of as-received Inconel 600, difference in FCGRs between lnconel 690 and lnconel 600 has been also discussed in detail.
The influence of processing on the fatigue and fatigue-creep behaviour of stainless steels. Plumbridge, W.J. J. Mater. Proce.~.~. Teehnol. (I Jan. 1 9 9 6 ) 5 6 ( 1 ~ ) , 502 510 Processing of engineering materials is generally performed to enhance their simple properties such as proof stress and ductility. Since many components experience complex conditions in service, it is important to determine how these are also influenced by processing. From a survey of published data, the paper explores the effects of prior ageing and deformation on the tensile, fatigue and fatigue-creep behaviour of stainless steels. Extended high temperature ageing is found to produce an increase in proof stress and a fall in ductility in comparison to the solution treated condition. Endurance during both continuous cycling fatigue and with cycles containing dwell periods is increased. While prior cold working is generally beneficial to the fatigue resistance of Type 316 stainless steel, it impairs performance in fatigue-creep. However, most cyclic lives fall withni a + 2 mult band. These findings are considered in terms of possible controlling mechanisms.
Effects of crack tip plasticity on fatigue crack propagation. Park, H.-B., Kim, K.-M., Lee, B.-W. and Rheem, K:S. J. NueL Mater. (1996) 230(1), 12-18 A simple model for fatigue crack propagation has been proposed based on the modified Dugdale model of crack tip plasticity and energy balance approach to stable crack propagation. To verify the proposed model, fatigue tests were performed on the specimens of Type 304 stainless steel and lnconel 718. To measure the effect of crack tip bluntness on the fatigue crack propagation, specimens of different thickness were used. Results show that the theoretical prediction of fatigue crack propagation agreed well with the experimental test results. It is suggested that the prediction of fatigue crack propagation should take account of the different plasticity related to the varia0on of specimen thickness, stress state and material's tearing modulus in the crack tip region.
Crystallographic preferred orientation induced by cyclic rolling contact loading. Voskamp, A.P. and Mittemeijer. E.J. Metall. Mater. Transact. A (1996) 27A (I 1). 3445 3465 Fine focus X ray diffraction methods have been applied to analyze the texture development of the territe phase during rolling contact fatigue of 6309 type deep groove ball bearing inner rings prepared from hardened and tempered SAE 52100 steel. Textures of the ferrite matrix as {100}<~110-"> and {111}<211> (where {hkl} denotes the crystallographic plane that is preferably parallel with the contact surface and < u v w > denotes the crystallographic direction that is preferably parallel with and in the directkm of over-rolling) have been identified in a small regkm below the rolling contact surface. These textures develop gradually with an increasing number of stress cycles and become noticeable in cortiunction with changes in resklual stress, microstram and volume fraction of retained austenite in the same region. Upon rolling contact loading, both textures can become very pronounced, while the shape of the subsurface volume, where plastic deformation takes place in particular, remains unchanged: material displacement in the subsurface volumes is <5 p_m in the three principal directions. Crack propagation m association with spalling fatigue failure has been shown to be related to the type of lexture developed. Diffraction patterns, graphs, photomicrographs, 22 ref.
Low-cycle fatigue behaviour of the model AI-Li-Zr and AI-Li-Cu-Zr alloys. Lewandowska, M.. Mizera. J. and Wyr=ykowskL .I.W. Mater. Sci. Forum (1996) 217-222 (3), 1359 1364 Cor!ferenee: Ahnninium Alloys--Their Physical and ,~,leehanical Preqwrtic,~, ICAA5, Part 3, Grenoble. France (1 5 July' 1996) In this work the low-cycle fatigue behaviour of two model AI Li alloys was investigated. The study has shown that the precipitates state has a significant effect on the low-cycle fatigue behaviour of the material, on both the stress response curve and fatigue life. The presence of the T1 precipitates makes the slip distribution more homogeneous, and thus improves the fatigue life of the material. Graphs, photomicrographs, 9 ref.
Fatigue crack propagation parallel to fibres in unidirectionally reinforced SCS-6/Timetal 21S. John. R., Laekev, A.F. and Ashbaugh. N.E. Scripm Materialia (1996) 35, 711-716 Crack growth parallel to fibres in unidirectional reinforced SCS-6/Timetal 21S is geometry independent, confirming the applicability of linear elastic fracture mechanics to describe the crack growth behaviour at room temperature. The composite exhibited stress ratio dependent crack growth response and high closure levels of K J K , , ~ up to 0.48. The use of effective AK based on closure correction enabled correlation of the crack growth behaviour of the composite up to R= 0.8. Use of net-section based correction correlated the composite and fibreless matrix crack growth behaviour at high stress intensity factor range (near-fracture). At lower stress intensity factor range, the net-section based prediction was conservative. Graphs, photomicrographs. 14 ref.
Mixed mode 1 and II fatigue threshold and crack deflection angle in SiCp/2024Al composite. Liu, P. and Wang, Z. Scripta Materialia (1996) 34, 1323 1330 In the past decade, extensive studies were made on fatigue crack propagation behaviour in particle or whisker reinforced metal matrix composites (MMCs) with specific emphasis on the pure mode [ fatigue crack growth threshold condition. However, the pure mode 1 case seldom occurred in practice. [n many components cracks are not normal to the maximum principal stress direction and the crack may not grow in the plane of initial crack. Therefore,
733
least squares analysis to estimate FL. FL (MPa) = 10.4 × d ~:2+ 51 × (%Si) + 16 × (%Mn) + 80. Graphs, photomicrographs, 34 ref.
Statistical analysis of high cycle fatigue crack growth: centre crack in aluminum panel. Huang, Y.C. and Z~u, P.C. Theoretical and Appl. Fracture Mech. (I Apr. 1996) 25 (I), 59 64
Corrosion resistance and corrosion fatigue strength of new titanium alloys for medical implants without V and Al. Okazaki, Y., lto, Y. Kyo. K. and 7~aeishi, 7" Mater. Sci. Eng. A (15 Aug. 1996) 213(I-2), 138-147
High cycle latigue crack growth results are obtained from a statistical analysis and compared with test data for an aluminium panel with a centre crack under constant amplitude cyclic load. The analysis makes use of a generalized FockPlanck equation that is satisfied by a union probabilistic density of stochastic variables of cycle number and crack length. Obtained are high degrees of modified expressions of the equation's coefficients and hence the analytical solution. A two-parameter fatigue crack growth rate relation is assumed together with a logarithmic average life distribution. Good agreement is obtained with test data for different initial crack lengths.
"['he corrosion resistance and the corrosion fatigue strength of Ti-15Zr~[Nb 4Ta 0.2Pd-0.20-0.05N and Ti-15Sn-4Nb-2Ta~0.2Pd 0.20 alloys were compared with those of Ti-6AI~4 V extra low interstitial (ELI), Ti-6AI-2Nb-ITa, pure Ti grade 2 and [3 type Ti-15C/cMo-5Zr-3AI alloys. Anodic polarization and corrosion fatigue testings were performed in various physiological saline solutions at 31(IK The corrosion fatigue test was carried out under the condition of a tension to tension mode with a sine wave at a stress ratio of 0.1 and at a frequency of 10 Hz. The tensile properties of these alloys were measured at room temperature. The change in current density was small up to passivity zone in I wt% lactic acid. P B S ( ) , calf serum and eagle's MEM+tetal bovine serum solutions except 5 wt% HCh The current density of Ti 15Zr~Nb~.Ta-0.2Pd-0.20-0.05N alloy at potential up to 5 V tend to be lower than that of Ti-6AI~J.V ELI. Otherwise passive current density of the [3 type Ti-15Mo-5Zr-3AI alloy was higher than that of o~ + [3 type alloys. The passive fihns formed on Ti-15Zr-4Nb-4Ta~).2Pd-0.20 alloy in the calf serum consisted mainly of TiO> ZrO,, NbeOs, Ta205 and Pd or PdO as demonstrated using X-ray photoelectron spectroscopy. The cycle to failure of Ti 15Zr~-Nb~ITa~I.2Pd-0.20-0.05N and Ti-15Sn-4Nb-4Ta~).2Pd~0.20 alloys annealed at 973 K for 7.2 ks increased with decreasing applied maximum stress. The fatigue strength at l0 s cycles in those alloys was about 600 MPa. The fatigue strength of Ti 6AI 2Nb ITa alloy at 10~ cycles was about 700 MPa. The fatigue strength of [3 type Ti-I 5Mo-5Zr-3AI alloy at 107 cycles was lower than that of ¢~ + [3 type alloys.
The microstructure dependence of fatigue behaviour in Ti-15Mo--5Zr3Al alloy. Tokaji. K.. Bian. J. C., Ogawa, T. and Naka]ima. M. Mater. Sei. Eng. A (1996) 213 (I 2), 86 92 In order to better understand the fundamental fatigue behaviour of a beta Ti 15Mo-5Z~3AI alloy, rotating bending fatigue tests have been carried out using materials with three different microstructures, that is, [3 grain sizes, which were solution treated at 735°C (STA735), 850°C (STA850), and 1000°C (STAI000) followed by aging at 500°C. It was found that STA735 showed the highest fatigue strength while the materials solution treated above the beta transus, STA850 and STAI(X)0, had fatigue lives which decreased with increasing solution treatment temperature, that is, [3 grain size. There was no significant difference in fatigue limit between the materials. Fatigue cracks were initiated as a result of cyclic slip deformation in STA735, but the crack initiation site was related to [3 groin boundaries in both STAB50 and STAI000. In particular, STA850 exhibited an unique initiation behaviour in which cracks were initiated on the specimen surface at higher stress levels, but subsurface crack initiation was observed at lower stress levels. Since STA735 indicated considerably slower crack initiation than STA850 and STA1000 and the growth rates of small cracks were almost the same for all the materials, the excellent fatigue strength of STA735 was primarily attributed to higher crack initiation resistance of its microstrncture.
Effect of heat treatment on fatigue crack growth rate of Inconel 690 and Inconel 600. Park. H.-B.. Kinl, }'%H.. Lee, B.-W. and Rheem. K.-S. J. Nuel. Mat. (1996) 231 (3), 204 212 The effects of heat treatment on fatigue crack growth rates (FCGRs) of lnconel 690 and Inconel 600 have been investigated in terms of carbide morphology and grain size. Cycling tests in air at room temperature have shown that FCGR in low stress intensity factor range (AK) region can be effectively reduced by increasing the grain boundary carbide precipitate size and grain size. Decrease in FCGR is attributed to the crack tip blunting at the precipitates of grain boundary chromium carbides. Compared with test data of as-received Inconel 600, difference in FCGRs between lnconel 690 and lnconel 600 has been also discussed in detail.
The influence of processing on the fatigue and fatigue-creep behaviour of stainless steels. Plumbridge, W.J. J. Mater. Proce.~.~. Teehnol. (I Jan. 1 9 9 6 ) 5 6 ( 1 ~ ) , 502 510 Processing of engineering materials is generally performed to enhance their simple properties such as proof stress and ductility. Since many components experience complex conditions in service, it is important to determine how these are also influenced by processing. From a survey of published data, the paper explores the effects of prior ageing and deformation on the tensile, fatigue and fatigue-creep behaviour of stainless steels. Extended high temperature ageing is found to produce an increase in proof stress and a fall in ductility in comparison to the solution treated condition. Endurance during both continuous cycling fatigue and with cycles containing dwell periods is increased. While prior cold working is generally beneficial to the fatigue resistance of Type 316 stainless steel, it impairs performance in fatigue-creep. However, most cyclic lives fall withni a + 2 mult band. These findings are considered in terms of possible controlling mechanisms.
Effects of crack tip plasticity on fatigue crack propagation. Park, H.-B., Kim, K.-M., Lee, B.-W. and Rheem, K:S. J. NueL Mater. (1996) 230(1), 12-18 A simple model for fatigue crack propagation has been proposed based on the modified Dugdale model of crack tip plasticity and energy balance approach to stable crack propagation. To verify the proposed model, fatigue tests were performed on the specimens of Type 304 stainless steel and lnconel 718. To measure the effect of crack tip bluntness on the fatigue crack propagation, specimens of different thickness were used. Results show that the theoretical prediction of fatigue crack propagation agreed well with the experimental test results. It is suggested that the prediction of fatigue crack propagation should take account of the different plasticity related to the varia0on of specimen thickness, stress state and material's tearing modulus in the crack tip region.
Crystallographic preferred orientation induced by cyclic rolling contact loading. Voskamp, A.P. and Mittemeijer. E.J. Metall. Mater. Transact. A (1996) 27A (I 1). 3445 3465 Fine focus X ray diffraction methods have been applied to analyze the texture development of the territe phase during rolling contact fatigue of 6309 type deep groove ball bearing inner rings prepared from hardened and tempered SAE 52100 steel. Textures of the ferrite matrix as {100}<~110-"> and {111}<211> (where {hkl} denotes the crystallographic plane that is preferably parallel with the contact surface and < u v w > denotes the crystallographic direction that is preferably parallel with and in the directkm of over-rolling) have been identified in a small regkm below the rolling contact surface. These textures develop gradually with an increasing number of stress cycles and become noticeable in cortiunction with changes in resklual stress, microstram and volume fraction of retained austenite in the same region. Upon rolling contact loading, both textures can become very pronounced, while the shape of the subsurface volume, where plastic deformation takes place in particular, remains unchanged: material displacement in the subsurface volumes is <5 p_m in the three principal directions. Crack propagation m association with spalling fatigue failure has been shown to be related to the type of lexture developed. Diffraction patterns, graphs, photomicrographs, 22 ref.
Low-cycle fatigue behaviour of the model AI-Li-Zr and AI-Li-Cu-Zr alloys. Lewandowska, M.. Mizera. J. and Wyr=ykowskL .I.W. Mater. Sci. Forum (1996) 217-222 (3), 1359 1364 Cor!ferenee: Ahnninium Alloys--Their Physical and ,~,leehanical Preqwrtic,~, ICAA5, Part 3, Grenoble. France (1 5 July' 1996) In this work the low-cycle fatigue behaviour of two model AI Li alloys was investigated. The study has shown that the precipitates state has a significant effect on the low-cycle fatigue behaviour of the material, on both the stress response curve and fatigue life. The presence of the T1 precipitates makes the slip distribution more homogeneous, and thus improves the fatigue life of the material. Graphs, photomicrographs, 9 ref.
Fatigue crack propagation parallel to fibres in unidirectionally reinforced SCS-6/Timetal 21S. John. R., Laekev, A.F. and Ashbaugh. N.E. Scripm Materialia (1996) 35, 711-716 Crack growth parallel to fibres in unidirectional reinforced SCS-6/Timetal 21S is geometry independent, confirming the applicability of linear elastic fracture mechanics to describe the crack growth behaviour at room temperature. The composite exhibited stress ratio dependent crack growth response and high closure levels of K J K , , ~ up to 0.48. The use of effective AK based on closure correction enabled correlation of the crack growth behaviour of the composite up to R= 0.8. Use of net-section based correction correlated the composite and fibreless matrix crack growth behaviour at high stress intensity factor range (near-fracture). At lower stress intensity factor range, the net-section based prediction was conservative. Graphs, photomicrographs. 14 ref.
Mixed mode 1 and II fatigue threshold and crack deflection angle in SiCp/2024Al composite. Liu, P. and Wang, Z. Scripta Materialia (1996) 34, 1323 1330 In the past decade, extensive studies were made on fatigue crack propagation behaviour in particle or whisker reinforced metal matrix composites (MMCs) with specific emphasis on the pure mode [ fatigue crack growth threshold condition. However, the pure mode 1 case seldom occurred in practice. [n many components cracks are not normal to the maximum principal stress direction and the crack may not grow in the plane of initial crack. Therefore,