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Fatigue behaviour of rope eutectoid steel wires
Fatigue Abstracts Fretting fatigue of an austenitic stainless steel in seawater. Takeuchi, M., Satoh, T., Mutoh, Y., Waterhouse, and Kon, Y. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 949-958 Fretting fatigue tests of an austenitic stainless steel used for a propeller tail shaft were carried out in seawater and in air. In seawater, fretting significantly reduced the fatigue strength; however, the fretting fatigue lives at higher levels of stress were longer than those in air. The tangential force coefficient (defined as the ratio of the frictional force amplitude and the contact load) in seawater was much lower than that in air and varied in the range from 0.3 to 0.5 during the fretting fatigue tests. The lower tangential force coefficient in seawater seems to be the main reason for the longer fretting fatigue life in seawater. The prediction of fretting fatigue life was made on the basis of elastic-plastic fracture mechanics, where the frictional force between the specimen and the contact pad was taken into consideration. The predicted fatigue lives agreed well with the experimental results in both air and seawater. Graphs, photomicrographs, 9 ref. Influence of contact loading on fretting fatigue behaviour.
Faanes, S. and Fernando, U.S. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 939-948 Fretting-induced cracking is commonly observed in industrial components that are in contact and are subjected to small oscillatory movements between them. Fretting causes a considerable reduction in fatigue strength. In this paper, recent knowledge on the short and long crack growth behaviour is applied to estimate crack propagation and fatigue life in fretting. The model is based on mode I stress intensity factors with a threshold modified for short cracks. The predicted results are compared with experiments and the influence of the contact pressure is examined. A good correlation between predictions and experimental results is obtained for crack growth rates as well as fatigue lives in terms of number of cycles to failure. It is seen that the increase of fatigue life observed for contact pressures above a certain level can be predicted by the crack growth model. Graphs, 12 ref. Representation of cyclic properties and hysteresis energy in a-brass using a ceratin class of elastic-plastic models.
63
Study on mechanical properties of Mn-B structural steel.
Yoshida, Y., Fukushima, M. and Sato, S. Proc. 9th International Congress on Heat Treatment and Surface Engineering and 5th French Open International Conference on Heat Treatment. NiceAcropolis, France (26-28 Sept. 1994) 465-473 The tensile, impact, fatigue, wear and bend properties of quenched and tempered Mn-B steel (Fe-0.33C-0.26Si-l.34Mn-0.15Cr with 23 ppm boron) were compared with those of a Cr-Mo steel (Fe-0.38C-0.21Si-0.85Mn-0.96Cr-0.16Mo) that had been similarly heat treated. It was shown that the tensile and bending strengths, wear resistance and hardness of the Mn-B steel were equal to those of the Cr-Mo steel. Charpy impact values and rotating bending fatigue strength of the Mn-B steel were superior to those of the Cr-Mo steel. The Mn-B steels are viewed as economical substitutes for Cr-Mo steels in power tools (e.g. circular saws and drills), gears, and spindles. Graphs, photomicrographs, 4 ref. Fatigue behaviour of rope eutectoid steel wires. Beretta, S., Boniardi, M. and MatteazzL S. Z. Metallkd. (Apr. 1994) 85 (4), 282-287
The fatigue behaviour of high-strength eutectoid steel wires is dependent on the surface roughness and microcrack growth conditions. In this paper, Wohler diagram, fatigue thresholds and crack growth rate of rope wires are obtained by means of experiments. Assuming that surface defects are induced by cold drawing and already exist when cyclic loads are applied, it is possible to predict the fatigue limit and ~-N diagram of the examined wires in accordance with a linear elastic fracture mechanics (LEFM) model. The values predicted are clsoe to the experimental results. Photomicrographs, graphs, 17 ref.
Characterization of low-cycle fatigue and creep-fatigue induced damage in a 316L stainless steel (Characterisierung yon durch niedrigperiodische Ermudang lind durch schleichende Ermudung verursachte Schaden im Falle van Nichtrustendem Stahl A 316).
Kaleta, J. and Zietek, G. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 919-930
Simon, S,, lbabe, J.M.R. and Fuentes, M. Z. Metallkd. (Apr. 1994) 85 (4), 273-281 (in German)
The paper deals with the analytical representation of the cyclic stress-strain curve, the hysteresis loop and the hysteresis energy for a single-phase abrass. The one- and two-parameter elastic-plastic models that were used were so chosen as to produce compatible representation of both the stress-strain relationship and the hysteresis loop. The models were checked with experimental data. The specimens were tested in uniaxial tensioncompression (R~= 1) under total strain amplitude control. The experiments covered a broad spectrum of lives from the low-cycle region through to the high-cycle regime, i.e. up to lives of N = 1 × 10 +6 cycles. The adopted measurement method enabled the cyclic deformation curve, hysteresis loop and hysteresis energy to be determined independently. It was shown that the modified Ramberg-Osgood model is a good approximation to the actual cyclic behaviour of a-brass. Graphs, 37 ref.
The damage induced by low-cycle fatigue and low-cycle fatigue/creep of a 316L stainless steel has been quantified both at the fracture surfaces and in the bulk of the tested material. Examination of the fracture surfaces revealed that continuous fatigue produces transgranular damage, but, with the incorporation of dwell periods into pure low-cycle fatigue cycles, an alternation of transgranular and intergranular damage regions is observed. A rationalization of both the mechanical low-cycle fatigue response of the material and the characterizing parameters of the damage induced by the deformation, for the investigated material and similar steels reported in the literature, has been performed. The predictions of the microstructural damagebased relationships yielded by this approach have been examined against experimental observations. Low-cycle fatigue crack nucleation and crack propagation lives agree with those experimentally observed. Finally, a reformulation of these relationships in terms of fracture mechanics has been attempted. The applicability of the concepts underlying this approach is critically examined. Photomicrographs, graphs, 33 ref.
Non-propagation conditions (AKth) and fatigue crack propagation threshold (~KT).
Marei, G. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 891-908. Fatigue crack propagation threshold values have been determined with two experimental methods, i.e. the constant R method and the constant Kmax method. Three materials, namely A17075-T7351 and Ti6AI4V STA in the LT- and TL-orientations, and Ti-turbine disk material (IMI 685) in the CRorientation, were investigated. The paper is divided into three parts. (1) Test conditions, experimental results and the conclusions drawn from the experimental results are presented, namely that the three different functional dependencies of AKth on R cannot be reconciled with present continuum mechanics concept. (2) Some facts used in conjunction with the da/dN-AKecr methodology are applied to the nonpropagation condition AKth. Parameters such as Kop, the threshold AKT, and a parameter KLL are investigated by numerical modelling of their individual influence on the AKth vs. R curves. This modelling work shows that the individual AKth vs. R curves are primarily dependent on the Kop independent of any particular cyclic loading condition. (3) The AK¢~ concept is applied to the experimental results obtained in the first part. Using either experimentally or semi-empirically determined Kop functions and the measured AKr values, the AKth vs. R curves of the three materials investigated were accurately reconstructed. It follows that the AKth VS. R curves of the individual materials are the natural consequence of the driving force for fatigue crack propagation, namely AKeff. Graphs, 32 ref.
A study of the growth of small fatigue cracks in a high strength steel using a surface acoustic wave technique.
Nelson, D.V., Yuce, H.H. and Ghow, L.G. Fatigue Fract. Eng. Mater. Struct. ( l l Nov. 1994) 17 (11), 1357-1369 An ultrasonic surface acoustic wave technique for studying the growth behaviour of small fatigue cracks is described. The technique allows crack depth and opening stress to be monitored continuously during the course of a fatigue test. Results are given for a 1740 MPa yield strength, siliconmodified, AISI 4340 steel tested under zero-to-tension cyclic loading. Good agreement is shown between acoustically determined crack depth and that measured by post-fracture optical microscopy. The monitoring of changing crack depth-to-surface length ratios during tests is also demonstrated. Acoustically determined crack opening stresses were found to be approx 10% higher than values determined by measurements of crack tip opening displacements by scanning electron microscopy. Effects on crack growth of two different specimen surface preparations, electropolishing and diamond paste polishing, are also reported. Growth rates in electropolished specimens were as much as an order of magnitude higher than in diamond paste polished specimens, which had a shallow but significant layer of compressive residual stress. Graphs. 27 ref.
Fatigue life and penetration behaviour of a surface-cracked plate under combined tension and bending.
Prediction of the fatigue life of laser welded stainless steel joints.
Nam, K.W., Ando, K., Ogura, N. and Matui, K. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 873-882 The present study investigates the fatigue crack propagation behaviour of surface cracks subjected to combined tension and bending stress. An estimation of fatigue crack growth behaviour employed the Newman-Raju formula before penetration, and a K solution, proposed by the authors, after penetration. Crack length aL at penetration increases with an increase in bending stress. The calculated fatigue crack shape was in good agreement with the experimental shape. It was also found that the crack growth behaviour and the crack shape after penetration can be satisfactorily evaluated using the K solution proposed by the authors. Graphs, 18 ref.
A fatigue scatter band has been computed for laser-welded austenitic stainless steel joints. These laser-welded steels have a very small heat-affected zone, The unified scatter band provided by standards for welded structural steels does not adequately describe the trend of the experimental data of laserwelded steels and this makes their design parameters scarcely realistic. The scatter band proposed in this paper has been computed by re-sorting experimental data relative to joints with high stress concentration factors and has subsequently been assessed with data relevant to butt-welded joints. Graphs, photomicrographs, 17 ref.
Dattoma, V. Fatigue Fraet. Eng. Mater. Struct. (11 Nov. 1994) 17 (11), 1335-1342
Faanes, S. and Fernando, U.S. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 939-948 Fretting-induced cracking is commonly observed in industrial components that are in contact and are subjected to small oscillatory movements between them. Fretting causes a considerable reduction in fatigue strength. In this paper, recent knowledge on the short and long crack growth behaviour is applied to estimate crack propagation and fatigue life in fretting. The model is based on mode I stress intensity factors with a threshold modified for short cracks. The predicted results are compared with experiments and the influence of the contact pressure is examined. A good correlation between predictions and experimental results is obtained for crack growth rates as well as fatigue lives in terms of number of cycles to failure. It is seen that the increase of fatigue life observed for contact pressures above a certain level can be predicted by the crack growth model. Graphs, 12 ref. Representation of cyclic properties and hysteresis energy in a-brass using a ceratin class of elastic-plastic models.
63
Study on mechanical properties of Mn-B structural steel.
Yoshida, Y., Fukushima, M. and Sato, S. Proc. 9th International Congress on Heat Treatment and Surface Engineering and 5th French Open International Conference on Heat Treatment. NiceAcropolis, France (26-28 Sept. 1994) 465-473 The tensile, impact, fatigue, wear and bend properties of quenched and tempered Mn-B steel (Fe-0.33C-0.26Si-l.34Mn-0.15Cr with 23 ppm boron) were compared with those of a Cr-Mo steel (Fe-0.38C-0.21Si-0.85Mn-0.96Cr-0.16Mo) that had been similarly heat treated. It was shown that the tensile and bending strengths, wear resistance and hardness of the Mn-B steel were equal to those of the Cr-Mo steel. Charpy impact values and rotating bending fatigue strength of the Mn-B steel were superior to those of the Cr-Mo steel. The Mn-B steels are viewed as economical substitutes for Cr-Mo steels in power tools (e.g. circular saws and drills), gears, and spindles. Graphs, photomicrographs, 4 ref. Fatigue behaviour of rope eutectoid steel wires. Beretta, S., Boniardi, M. and MatteazzL S. Z. Metallkd. (Apr. 1994) 85 (4), 282-287
The fatigue behaviour of high-strength eutectoid steel wires is dependent on the surface roughness and microcrack growth conditions. In this paper, Wohler diagram, fatigue thresholds and crack growth rate of rope wires are obtained by means of experiments. Assuming that surface defects are induced by cold drawing and already exist when cyclic loads are applied, it is possible to predict the fatigue limit and ~-N diagram of the examined wires in accordance with a linear elastic fracture mechanics (LEFM) model. The values predicted are clsoe to the experimental results. Photomicrographs, graphs, 17 ref.
Characterization of low-cycle fatigue and creep-fatigue induced damage in a 316L stainless steel (Characterisierung yon durch niedrigperiodische Ermudang lind durch schleichende Ermudung verursachte Schaden im Falle van Nichtrustendem Stahl A 316).
Kaleta, J. and Zietek, G. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 919-930
Simon, S,, lbabe, J.M.R. and Fuentes, M. Z. Metallkd. (Apr. 1994) 85 (4), 273-281 (in German)
The paper deals with the analytical representation of the cyclic stress-strain curve, the hysteresis loop and the hysteresis energy for a single-phase abrass. The one- and two-parameter elastic-plastic models that were used were so chosen as to produce compatible representation of both the stress-strain relationship and the hysteresis loop. The models were checked with experimental data. The specimens were tested in uniaxial tensioncompression (R~= 1) under total strain amplitude control. The experiments covered a broad spectrum of lives from the low-cycle region through to the high-cycle regime, i.e. up to lives of N = 1 × 10 +6 cycles. The adopted measurement method enabled the cyclic deformation curve, hysteresis loop and hysteresis energy to be determined independently. It was shown that the modified Ramberg-Osgood model is a good approximation to the actual cyclic behaviour of a-brass. Graphs, 37 ref.
The damage induced by low-cycle fatigue and low-cycle fatigue/creep of a 316L stainless steel has been quantified both at the fracture surfaces and in the bulk of the tested material. Examination of the fracture surfaces revealed that continuous fatigue produces transgranular damage, but, with the incorporation of dwell periods into pure low-cycle fatigue cycles, an alternation of transgranular and intergranular damage regions is observed. A rationalization of both the mechanical low-cycle fatigue response of the material and the characterizing parameters of the damage induced by the deformation, for the investigated material and similar steels reported in the literature, has been performed. The predictions of the microstructural damagebased relationships yielded by this approach have been examined against experimental observations. Low-cycle fatigue crack nucleation and crack propagation lives agree with those experimentally observed. Finally, a reformulation of these relationships in terms of fracture mechanics has been attempted. The applicability of the concepts underlying this approach is critically examined. Photomicrographs, graphs, 33 ref.
Non-propagation conditions (AKth) and fatigue crack propagation threshold (~KT).
Marei, G. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 891-908. Fatigue crack propagation threshold values have been determined with two experimental methods, i.e. the constant R method and the constant Kmax method. Three materials, namely A17075-T7351 and Ti6AI4V STA in the LT- and TL-orientations, and Ti-turbine disk material (IMI 685) in the CRorientation, were investigated. The paper is divided into three parts. (1) Test conditions, experimental results and the conclusions drawn from the experimental results are presented, namely that the three different functional dependencies of AKth on R cannot be reconciled with present continuum mechanics concept. (2) Some facts used in conjunction with the da/dN-AKecr methodology are applied to the nonpropagation condition AKth. Parameters such as Kop, the threshold AKT, and a parameter KLL are investigated by numerical modelling of their individual influence on the AKth vs. R curves. This modelling work shows that the individual AKth vs. R curves are primarily dependent on the Kop independent of any particular cyclic loading condition. (3) The AK¢~ concept is applied to the experimental results obtained in the first part. Using either experimentally or semi-empirically determined Kop functions and the measured AKr values, the AKth vs. R curves of the three materials investigated were accurately reconstructed. It follows that the AKth VS. R curves of the individual materials are the natural consequence of the driving force for fatigue crack propagation, namely AKeff. Graphs, 32 ref.
A study of the growth of small fatigue cracks in a high strength steel using a surface acoustic wave technique.
Nelson, D.V., Yuce, H.H. and Ghow, L.G. Fatigue Fract. Eng. Mater. Struct. ( l l Nov. 1994) 17 (11), 1357-1369 An ultrasonic surface acoustic wave technique for studying the growth behaviour of small fatigue cracks is described. The technique allows crack depth and opening stress to be monitored continuously during the course of a fatigue test. Results are given for a 1740 MPa yield strength, siliconmodified, AISI 4340 steel tested under zero-to-tension cyclic loading. Good agreement is shown between acoustically determined crack depth and that measured by post-fracture optical microscopy. The monitoring of changing crack depth-to-surface length ratios during tests is also demonstrated. Acoustically determined crack opening stresses were found to be approx 10% higher than values determined by measurements of crack tip opening displacements by scanning electron microscopy. Effects on crack growth of two different specimen surface preparations, electropolishing and diamond paste polishing, are also reported. Growth rates in electropolished specimens were as much as an order of magnitude higher than in diamond paste polished specimens, which had a shallow but significant layer of compressive residual stress. Graphs. 27 ref.
Fatigue life and penetration behaviour of a surface-cracked plate under combined tension and bending.
Prediction of the fatigue life of laser welded stainless steel joints.
Nam, K.W., Ando, K., Ogura, N. and Matui, K. Fatigue Fract. Eng. Mater. Struct. (Aug. 1994) 17 (8), 873-882 The present study investigates the fatigue crack propagation behaviour of surface cracks subjected to combined tension and bending stress. An estimation of fatigue crack growth behaviour employed the Newman-Raju formula before penetration, and a K solution, proposed by the authors, after penetration. Crack length aL at penetration increases with an increase in bending stress. The calculated fatigue crack shape was in good agreement with the experimental shape. It was also found that the crack growth behaviour and the crack shape after penetration can be satisfactorily evaluated using the K solution proposed by the authors. Graphs, 18 ref.
A fatigue scatter band has been computed for laser-welded austenitic stainless steel joints. These laser-welded steels have a very small heat-affected zone, The unified scatter band provided by standards for welded structural steels does not adequately describe the trend of the experimental data of laserwelded steels and this makes their design parameters scarcely realistic. The scatter band proposed in this paper has been computed by re-sorting experimental data relative to joints with high stress concentration factors and has subsequently been assessed with data relevant to butt-welded joints. Graphs, photomicrographs, 17 ref.
Dattoma, V. Fatigue Fraet. Eng. Mater. Struct. (11 Nov. 1994) 17 (11), 1335-1342