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Fatigue and fretting fatigue behaviours of A2024-T6 composite materials reinforced with 20 vol.% SiC particles
Fatigue Abstracts Fatigue and fretting fatigue behaviours of A2024-T6 composite materials reinforced with 20 vol.% SiC particles. Maruyama, N., Sumita, M. and
Nakazaw, K. J. Jpn. Inst. Met. (Nov. 1993) 57(11), 1268-1274 (in Japanese) A study has been made of the role of silicon carbide (SIC) particles in the fatigue strength and fretting fatigue strength at high cycles using powder metallurgy 2024-T6 aluminium metal-matrix composites reinforced with 20 vol.% SiC particles with the mean sizes of 2 and 16 ttm. The 107 cycles plain fatigue strengths of the composites were within the values estimated on the basis of the change of the elastic modulus and the ultimate tensile strength due to the reinforcement. The 107 cycles fretting fatigue strengths in the composites were approx 30% higher than those estimated. This suggested that the increase in fretting fatigue strength in the composites was probably due to low stress concentration at the fretted area and crack growth resistance caused by avoiding the SiC particles at low stress intensities. Graphs, photomicrographs, 14 ref.
Ion implantation effects on surface-mechanical properties of metals and polymers. Rao, G.R. Oak Ridge National Laboratory Report DE93014661/XAB (1993) 207 pp
Fatigue of the eight complex alloys based on Fe-13Cr-15Ni-2Mo2Mn-0.2Ti-0.8Si-0.06C, and single-crystal Fe-15Cr-15Ni, implanted with 400 keV B + and 550 keV N + (total dose 2.3 × 1016 ions/cm 2) was examined. Creep at 600°C was also examined. The dual implantation increased hardness but decreased fatigue life of the eight complex alloys. An optimum strengthening level and a shift to grain boundary cracking were determined. The single crystals also showed reduced fatigue life after implantation. Hightemperature creep of E1 and B1 alloys was improved by the dual implantation. Four polymers (PE, polypropylene, polystyrene, polyethersulfone) were implanted with 200 keV B* to three different doses. PS was also implanted with both B + and Ar ÷. Near-surface hardness and tribological properties were measured. The hardness increased with dose and energy; wear also improved, with an optimum dose.
The effect of intercritical heat treatments on the properties of the ship plates.
Munteanu, V., Levcovici, D.T., Oane, P. and Badea, P. Proc. Conf. International Symposium on Low-Carbon Steels for the 90's, Pittsburgh, PA, USA, 18-21 Oct. 1993, pp. 571-576 Generally, it is considered that the treatments involving incomplete austenitization of the hypoeutectoid steels deteriorate some mechanical properties such as the fatigue strength and ductility. However, a series of papers has recently been published concerning the successful application of intercritical heat treatments to some low-carbon steel grades (0.1-0.3%). As part of the concerns to improve the quality of fiat products and decrease the production costs, research work was carried out regarding the effect of intercritical treatments on ship plates rolled of niobium microalloy steel grades. This paper presents the results of this research work based on a significant number of determinations showing that even in this case the heat treatments based on the incomplete austenitization can result in improvement of the process and mechanical properties. The increase of the strength values including the fatigue strength and decrease of transition-temperature ductile fracture has been obtained while reducing fuel consumption. Graphs, phase diagrams, 3 ref. Heat treatment process for a nickel based superalloy. Rongvaux, J.-M.
(SNECMA) Patent GB 2267507 8 Dec. 1993 A nickel-based superalloy known by the designation '718' and having a typical composition comprising, in wt.%, chromium 19, iron 18, niobium 5, and the remainder Ni, is subjected, after the usual thermomechanical and heat treatment steps, to an additional annealing step wherein the temperature and duration are selected from the following ranges as desired: 800°C for 5-30 h; 750~C for 25-70 h; and 700°C for 100-300 h. This leads to a definite improvement in the behaviour of parts made from the superalloy, in terms of fatigue cracking, when used at temperatures > 650°C.
Kinetics of fatigue-induced phase transformation in a metastable austenitic 304 L-type steel at low temperatures. Maier, H.J., Donth, B. and Schneeweiss, O. Scr. Metall. Mater. (15 Aug. 1993) 29(4), 521-526 An AISI 304 L-type metastable austenitic stainless steel was cyclically deformed at temperatures of 103 and 203 K, to investigate the kinetics of martensitic transformation during low-temperature cyclic deformation. The specimens had a 4.8 mm gauge length and a 2.7 mm gauge diameter, and were fatigue tested at a plastic strain range of 2.5 × 10-2. These tests indicated that the ultimate tensile strength at room temperature is governed primarily by the amount of fatigue-induced ¢t-martensite; that the increase in cyclic stress amplitude during low-temperature fatigue deformation is determined mainly by the amount of fatigue-induced c~-martensite; and that under the test conditions used, the martensite transformation requires plastic deformation to occur. In addition, the rate of fatigue-induced martensite formation increases with decreasing temperatures, the maximum volume fraction of ct-martensite obtainable remaining constant. It also appears that cyclic deformation can give higher maximum martensite volume contents than monotonic deformation. Graphs, photomicrographs, 23 ref.
592
Fatigue, 1994, Vol 16, November
Effect of heat treatment on low cycle fatigue properties of zircaloy-4. Xiao, L. and Gu, H.C. Xiyou Jinshu Cuiliao yu Gongcheng (Rare Metal Materials and Engineering)
(Oct. 1993) 22(5), 61-66 (in Chinese) Low-cycle fatigue tests have been performed for zircaloy-4 specimens in recrystallized and stress-relieved conditions. It can be concluded that for zircaloy-4 the cyclic stress-strain curves lie above the monotonic ones for both conditions, exhibiting cyclic hardening behaviour. The lifetimes of specimens in the recrystallized condition are longer than those in the stressrelieved condition under constant plastic strain amplitudes. The fracture surfaces of fatigued specimens were observed by SEM. Based on the experimental results, the effect of heat treatment on fatigue lives is analysed and the criterion of materials selection is discussed. Graphs, photomicrographs, 8 ref. Influence of cerium on crack closure effect and intrinsic fatigue crack growth resistance in AI-Li alloy. Ni, Y.F., Wang, H. and Chen, Z.
Xiyou Jinshu Cailiao yu Gongcheng (Rare Metal Materials and Engineering) (Oct. 1993) 22(5), 40-44 (in Chinese) Fatigue crack growth behaviours for the alloys 2090, 8090, 2090Ce, and 8090Ce have been studied. The results show that, at the same strength level, the fatigue long crack growth resistance for A1-Li alloys by addition of trace cerium is superior to that of general aluminium alloys, due to their high level of crack closure. The intrinsic growth resistance and crack closure for AI-Li alloy 2090 are increased by the addition of trace Ce. On the contrary, it has little effect on crack closure for AI-Li alloy 8090, but its intrinsic growth resistance decreases. Graphs, 4 ref. Small crack progagation threshold of carbon tool steel under combined stresses.
Chen, J. Q. Acta Metall. Sin. (China) (Oct. 1993) 29(10), A461-A467 (in Chinese) By investigating the criteria of slip initiation, fatigue fracture and surface crack progagation in a carbon tool steel under combined stresses, fatigue features of smooth and cracked specimens are discussed from the point of view of local stress. Results show that, for short cracks, linear elastic fracture mechanics is applicable provided that the nominal stress is smaller than the slip initiation threshold stress of the material, and the size of plastic zone around a crack tip is almost a constant regardless of the crack length and deformation mode under threshold condition. Graphs, photomicrographs, 4 ref. Preparation of diffusion bonding and adhesive bonding of aluminium alloy specimens for fracture toughness and fatigue crack growth resistance measurements in different orientations. Hariprasad, S., Sastry, S.M.L. and Jerina.
K.L. Mater. Sci. Eng. A (15 Sept. 1993) A169(1-2), LI3-LI6 Two new methods were used to prepare specimens for the determination of fracture toughness and fatigue crack growth resistance in the short transverse direction of aluminium alloy mill products. Six mm thick specimens for fracture toughness measurements were fabricated from plates of an A I - F e - V - S i alloy produced by the planar flow casting (PFC) process. The fracture toughness values range from 13.39 MPa m 1/2 in the SL orientation to 30.85 MPa m 1/2 in the LT orientation. The techniques are useful to determine the anistropy of AI alloy mill products. Graphs, photomicrographs, 5 ref. Fatigue behaviour of ~mpered ball bearing steel I1. [Vermoeiingsresponsie van Gehard Kogellagerstaal. II], Voskamp, A.P. Materialen (Sept. 1993) (7) 21-23, 25-28 (In Dutch)
This part considers fatigue cracks and similar defects due to irregularities in the surface of ball bearing steels. These can be caused by temporary or final types of deformation and can lead to significant changes in grain structure of the steel. The commencement of fatigue behaviour is described in detail, aided by graphs of actual cases investigated. Four main phases of fatigue failure commencement are detailed and the second is investigated in considerable detail. The paper does not indicate reasons for the early failure of some bearings during what is termed the 'shakedown period'. These may be due to vibration stresses incurred in transit. Graphs, photomicrographs, 17 ref. Low cycle fatigue life prediction of diesel engine heating components. Gu,
Z.T., Ha, G., Chao, R.A. and Yang, W.J. Trans. Chin. Soc. Internal Combustion Engines (1993) 11(4), 298-305 (in Chinese) The thermal load condition of marine diesel engine is analysed, then the stress-strain hysteresis cycles are determined. On this basis the low-cycle fatigue lives of heating components are calculated by the strain-range partitioning method and the hysteresis energy method. By comparing the calculated results with the damaged component of a test machine due to starting and stopping in practical application, it is verified that both methods have a certain accuracy, because both are considered the interaction of fatigue and creep. During calculating and testing, the equivalent temperature of thermal fatigue and high-temperature low-cycle fatigue is the maximum temperature T2 and the stress-strain cycle is according to peripheral stress and strain, because the components are similar to the axisymmetric body. ZL104 aluminum-base alloy, 1Crl3, 42CrMo, 35CrMo steels, QT60-2 nodular iron, and HT-25-47 grey iron are discussed. Graphs, 8 ref.
Nakazaw, K. J. Jpn. Inst. Met. (Nov. 1993) 57(11), 1268-1274 (in Japanese) A study has been made of the role of silicon carbide (SIC) particles in the fatigue strength and fretting fatigue strength at high cycles using powder metallurgy 2024-T6 aluminium metal-matrix composites reinforced with 20 vol.% SiC particles with the mean sizes of 2 and 16 ttm. The 107 cycles plain fatigue strengths of the composites were within the values estimated on the basis of the change of the elastic modulus and the ultimate tensile strength due to the reinforcement. The 107 cycles fretting fatigue strengths in the composites were approx 30% higher than those estimated. This suggested that the increase in fretting fatigue strength in the composites was probably due to low stress concentration at the fretted area and crack growth resistance caused by avoiding the SiC particles at low stress intensities. Graphs, photomicrographs, 14 ref.
Ion implantation effects on surface-mechanical properties of metals and polymers. Rao, G.R. Oak Ridge National Laboratory Report DE93014661/XAB (1993) 207 pp
Fatigue of the eight complex alloys based on Fe-13Cr-15Ni-2Mo2Mn-0.2Ti-0.8Si-0.06C, and single-crystal Fe-15Cr-15Ni, implanted with 400 keV B + and 550 keV N + (total dose 2.3 × 1016 ions/cm 2) was examined. Creep at 600°C was also examined. The dual implantation increased hardness but decreased fatigue life of the eight complex alloys. An optimum strengthening level and a shift to grain boundary cracking were determined. The single crystals also showed reduced fatigue life after implantation. Hightemperature creep of E1 and B1 alloys was improved by the dual implantation. Four polymers (PE, polypropylene, polystyrene, polyethersulfone) were implanted with 200 keV B* to three different doses. PS was also implanted with both B + and Ar ÷. Near-surface hardness and tribological properties were measured. The hardness increased with dose and energy; wear also improved, with an optimum dose.
The effect of intercritical heat treatments on the properties of the ship plates.
Munteanu, V., Levcovici, D.T., Oane, P. and Badea, P. Proc. Conf. International Symposium on Low-Carbon Steels for the 90's, Pittsburgh, PA, USA, 18-21 Oct. 1993, pp. 571-576 Generally, it is considered that the treatments involving incomplete austenitization of the hypoeutectoid steels deteriorate some mechanical properties such as the fatigue strength and ductility. However, a series of papers has recently been published concerning the successful application of intercritical heat treatments to some low-carbon steel grades (0.1-0.3%). As part of the concerns to improve the quality of fiat products and decrease the production costs, research work was carried out regarding the effect of intercritical treatments on ship plates rolled of niobium microalloy steel grades. This paper presents the results of this research work based on a significant number of determinations showing that even in this case the heat treatments based on the incomplete austenitization can result in improvement of the process and mechanical properties. The increase of the strength values including the fatigue strength and decrease of transition-temperature ductile fracture has been obtained while reducing fuel consumption. Graphs, phase diagrams, 3 ref. Heat treatment process for a nickel based superalloy. Rongvaux, J.-M.
(SNECMA) Patent GB 2267507 8 Dec. 1993 A nickel-based superalloy known by the designation '718' and having a typical composition comprising, in wt.%, chromium 19, iron 18, niobium 5, and the remainder Ni, is subjected, after the usual thermomechanical and heat treatment steps, to an additional annealing step wherein the temperature and duration are selected from the following ranges as desired: 800°C for 5-30 h; 750~C for 25-70 h; and 700°C for 100-300 h. This leads to a definite improvement in the behaviour of parts made from the superalloy, in terms of fatigue cracking, when used at temperatures > 650°C.
Kinetics of fatigue-induced phase transformation in a metastable austenitic 304 L-type steel at low temperatures. Maier, H.J., Donth, B. and Schneeweiss, O. Scr. Metall. Mater. (15 Aug. 1993) 29(4), 521-526 An AISI 304 L-type metastable austenitic stainless steel was cyclically deformed at temperatures of 103 and 203 K, to investigate the kinetics of martensitic transformation during low-temperature cyclic deformation. The specimens had a 4.8 mm gauge length and a 2.7 mm gauge diameter, and were fatigue tested at a plastic strain range of 2.5 × 10-2. These tests indicated that the ultimate tensile strength at room temperature is governed primarily by the amount of fatigue-induced ¢t-martensite; that the increase in cyclic stress amplitude during low-temperature fatigue deformation is determined mainly by the amount of fatigue-induced c~-martensite; and that under the test conditions used, the martensite transformation requires plastic deformation to occur. In addition, the rate of fatigue-induced martensite formation increases with decreasing temperatures, the maximum volume fraction of ct-martensite obtainable remaining constant. It also appears that cyclic deformation can give higher maximum martensite volume contents than monotonic deformation. Graphs, photomicrographs, 23 ref.
592
Fatigue, 1994, Vol 16, November
Effect of heat treatment on low cycle fatigue properties of zircaloy-4. Xiao, L. and Gu, H.C. Xiyou Jinshu Cuiliao yu Gongcheng (Rare Metal Materials and Engineering)
(Oct. 1993) 22(5), 61-66 (in Chinese) Low-cycle fatigue tests have been performed for zircaloy-4 specimens in recrystallized and stress-relieved conditions. It can be concluded that for zircaloy-4 the cyclic stress-strain curves lie above the monotonic ones for both conditions, exhibiting cyclic hardening behaviour. The lifetimes of specimens in the recrystallized condition are longer than those in the stressrelieved condition under constant plastic strain amplitudes. The fracture surfaces of fatigued specimens were observed by SEM. Based on the experimental results, the effect of heat treatment on fatigue lives is analysed and the criterion of materials selection is discussed. Graphs, photomicrographs, 8 ref. Influence of cerium on crack closure effect and intrinsic fatigue crack growth resistance in AI-Li alloy. Ni, Y.F., Wang, H. and Chen, Z.
Xiyou Jinshu Cailiao yu Gongcheng (Rare Metal Materials and Engineering) (Oct. 1993) 22(5), 40-44 (in Chinese) Fatigue crack growth behaviours for the alloys 2090, 8090, 2090Ce, and 8090Ce have been studied. The results show that, at the same strength level, the fatigue long crack growth resistance for A1-Li alloys by addition of trace cerium is superior to that of general aluminium alloys, due to their high level of crack closure. The intrinsic growth resistance and crack closure for AI-Li alloy 2090 are increased by the addition of trace Ce. On the contrary, it has little effect on crack closure for AI-Li alloy 8090, but its intrinsic growth resistance decreases. Graphs, 4 ref. Small crack progagation threshold of carbon tool steel under combined stresses.
Chen, J. Q. Acta Metall. Sin. (China) (Oct. 1993) 29(10), A461-A467 (in Chinese) By investigating the criteria of slip initiation, fatigue fracture and surface crack progagation in a carbon tool steel under combined stresses, fatigue features of smooth and cracked specimens are discussed from the point of view of local stress. Results show that, for short cracks, linear elastic fracture mechanics is applicable provided that the nominal stress is smaller than the slip initiation threshold stress of the material, and the size of plastic zone around a crack tip is almost a constant regardless of the crack length and deformation mode under threshold condition. Graphs, photomicrographs, 4 ref. Preparation of diffusion bonding and adhesive bonding of aluminium alloy specimens for fracture toughness and fatigue crack growth resistance measurements in different orientations. Hariprasad, S., Sastry, S.M.L. and Jerina.
K.L. Mater. Sci. Eng. A (15 Sept. 1993) A169(1-2), LI3-LI6 Two new methods were used to prepare specimens for the determination of fracture toughness and fatigue crack growth resistance in the short transverse direction of aluminium alloy mill products. Six mm thick specimens for fracture toughness measurements were fabricated from plates of an A I - F e - V - S i alloy produced by the planar flow casting (PFC) process. The fracture toughness values range from 13.39 MPa m 1/2 in the SL orientation to 30.85 MPa m 1/2 in the LT orientation. The techniques are useful to determine the anistropy of AI alloy mill products. Graphs, photomicrographs, 5 ref. Fatigue behaviour of ~mpered ball bearing steel I1. [Vermoeiingsresponsie van Gehard Kogellagerstaal. II], Voskamp, A.P. Materialen (Sept. 1993) (7) 21-23, 25-28 (In Dutch)
This part considers fatigue cracks and similar defects due to irregularities in the surface of ball bearing steels. These can be caused by temporary or final types of deformation and can lead to significant changes in grain structure of the steel. The commencement of fatigue behaviour is described in detail, aided by graphs of actual cases investigated. Four main phases of fatigue failure commencement are detailed and the second is investigated in considerable detail. The paper does not indicate reasons for the early failure of some bearings during what is termed the 'shakedown period'. These may be due to vibration stresses incurred in transit. Graphs, photomicrographs, 17 ref. Low cycle fatigue life prediction of diesel engine heating components. Gu,
Z.T., Ha, G., Chao, R.A. and Yang, W.J. Trans. Chin. Soc. Internal Combustion Engines (1993) 11(4), 298-305 (in Chinese) The thermal load condition of marine diesel engine is analysed, then the stress-strain hysteresis cycles are determined. On this basis the low-cycle fatigue lives of heating components are calculated by the strain-range partitioning method and the hysteresis energy method. By comparing the calculated results with the damaged component of a test machine due to starting and stopping in practical application, it is verified that both methods have a certain accuracy, because both are considered the interaction of fatigue and creep. During calculating and testing, the equivalent temperature of thermal fatigue and high-temperature low-cycle fatigue is the maximum temperature T2 and the stress-strain cycle is according to peripheral stress and strain, because the components are similar to the axisymmetric body. ZL104 aluminum-base alloy, 1Crl3, 42CrMo, 35CrMo steels, QT60-2 nodular iron, and HT-25-47 grey iron are discussed. Graphs, 8 ref.