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The United Kingdom offshore steels research project—phase II
This section contains abstracts of selected articles, technical reports, dissertations and patents concerned with fatigue. It is prepared in collaboration with Materials Information, a joint service of The Institute of Materials and ASM International. Readers wishing to obtain the full text of articles abstracted here should contact either: The Institute of Materials, 1 Carlton House Terrace, London S W l Y 5DB, UK, or: ASM International, Metals Park, OH 44073, USA (not /nternationa/ Journal of Fatigue). The fees charged for photocopying articles are £7.00 for the first ten pages and £3.00 per additional ten pages (UK office), or $10.00 for the first ten pages and $4.00 per additional ten pages (US Office).
General Flexural fatigue behaviour of a cast P100 graphite-fibre-reinforcad 6061 aluminium composite laminate. Dutta I., Mitra, S. and Hansen, R.C. Scr. Metal/. Mater. J u l y 1991 25, (7), 1601-1606 A review studies the flexural fatigue behaviour of cross-plied graphite-reinforced 6061 AI matrix laminates with respect to the effect of fibre orientation and the mechanisms of crack initiation and propagation. Two orientations of the composite were cut. The first (TLT) had the fibres in the two outer plies oriented transverse to the long axis of the specimen, while the second (LTL) had the fibres in the outer plies oriented parallel to the specimen axis. An unreinforced 6061 AI, obtained from Alcoa, and heat treated to duplicate the matrix ageing condition in the composite, was used as a basis for comparison. The fatigue strength of the composites was found to depend strongly on the laminate orientation, and for both TLT and LTL, the longitudinal laminae contributed to the majority of the fatigue lives. Graphs, photomicrographs. 20 refs.
A study of fatigue crack growth in a particulate-reinforced A I - S i alloy at 23 and 220 °C. Healy, J.C. and Beevers, C.J. Mater. Sci. Eng. A Aug. 1991 A142, (2), 1 8 3 - 1 9 2 A study of short- and long-fatigue-crack growth in A356. a cast AI-Si alloy, reinforced with 20% volume fraction of silicon carbide (SIC) particulates, was carried out at 23 °C. Long-crack growth tests were performed at 220 °C. Short-crack growth was observed below the long-crack threshold stress intensity at 23 °C and was dominated by interactions between the crack tips and the SiC particulate. In the long-crack tests at R - 0.1 and R - 0.5, a stress ratio effect on crack growth was observed at 23 °C, which was more marked than that observed at 220 °C. Examination of fatigue fracture surfaces revealed a matrix-dominated mode of crack growth at 220°C compared with that at 23 °C where the SiC particulates played a significant role in the fatigue fracture process. Graphs, photomicrographs. 16 refs.
Remaining fatigue life of old steel bridges. Mang, F. and Bucak, O. Proc. Conf. on Testing of Metals for Structures, Naples, Italy, May 1990 An investigation of a complete bridge structure of the 'museum railway' in the German community of Blumberg and two bridge structures of the 'Deutsche Bundesbahn" is described. The results of component tests are compared with data taken from the literature and other results of similar investigations. Graphs. 13 refs.
A stochastic model for estimating the fatigue life of structural steel details. Castiglioni, C.A. J. Construct. Steel Res. 1991 18, (2), 1 1 1 - 1 3 8 A model is presented that allows the numerical simulation of fatigue crack growth in structural steel details, taking into account the effects of random variations in both the applied loads and the material parameters. A detailed analysis of the numerical code is presented, as well as a discussion of how all the parameters governing the crack growth have been considered and implemented. The calibration needed to simulate correctly the fatigue tests on structural details of practical interest is also discussed. Initially, the effects of the individual parameters of the model are investigated. Next the behaviour of certain typical structural steel details is simulated, and the numerical results are compared with available test data, for both the cases of constant- and variable-amplitude loading. The agreement between the test data and the proposed model has proved to be decidedly satisfactory, although the numerical model can be improved further. Graphs. 35 refs.
Activities in the field of plant life evaluation, life extension and plant improvement. Erve, M. and Bartholome, G. Nucl. Eng. Design J u l y 1991 128, (1), 1 0 3 - 1 1 4 The adequate margin of safety achieved in the as-built condition for a nuclear power plant has to be maintained throughout the whole life of the plant. To ensure this, a systematic evaluation of the lifetimes of safety-related items should be performed in due time in the light of new developments. The results can also be used for the purpose of life extension and licence renewal. Siemens has developed an integral analysis concept by practical experience. The analysis can result in corrective actions with respect to the life extension of plant components and systems or can lead to measures for plant improvement. Examples of the activities performed are given. Materials discussed include austenitic stainless steels, 20MnMoNi5 5, 15MnNi6 3, Inconel 600, Inconel 690 and Incoloy 800. Graphs. 18 refs.
272
Structure and properties of ion-plated aluminium bronze films. Gu, Z., Wang, L. and Yang, L. Mater. Sci. Eng. A J u l y 1991 A140, (1-2), 6 8 7 - 6 9 0 Alum/n/urn bronze films were deposited using the hollow-cathode discharge (HCD) ion plating technique, and their structures and properties were examined and studied. Both film and substrate were QAI 10-4-4 (10wt.% AI, 4wt.% Fe, 4wt.% Ni, balance Cu). The results show that ion-plated AI bronze films have the same structure as the bulk material, but their grains are much smaller than those of the bulk material. The results of X-ray diffraction show that ion-plated AI bronze has more 52 (CugAI4) and K (NiAI) phases than the bulk material, and the residual stresses in the films are compressive. The ion-plated films increase the wear resistance of AI bronze material and its fatigue-resistant properties. Photomicrographs, diffraction patterns. 2 refs. Plasma surface engineering of a l o w - a l l o y steel. Sun, Y. and Bell, T. Mater. Sci. Eng. A J u l y 1991 A140, (1-2), 4 1 9 - 4 3 4 The surface of a low-alloy steel (En40B) has been engineered in the plasma of a glow discharge via plasma nitriding and ion plating of titanium nitride coatings on the nitrided substrates with the purpose of enhancing the surface properties and fatigue strength. The nitriding response of the steel has been accessed by the evaluation of the phase composition, layer thickness, hardness profile, residual stresses, and of the nitrogen and carbon distributions. The wear and fatigue characteristics of the plasma-nitrided steel have been investigated and simple models have been developed to describe the influence of properties such as the depth and strength of the nitrided case on the fatigue limit and the load-bearing capacity of the low-alloy steel. To improve further the tribological properties and load-bearing capacity of the tow-alloy steel, a duplex plasma technique has been developed for surface engineering. This is achieved by plasma nitriding the steel first so as to produce a thick, strong subsurface and then depositing a thin, hard and wear-resistant titanium nitride coating on the nitrided substrata by ion plating. Dry-sliding wear tests demonstrated that the duplex-treated steel, that is the titanium nitride coati ng-nitrided steel composite, not only exhibited enhanced wear resistance over the as-nitrided steel (by a factor of two to eight) but also had a much higher load-bearing capacity than the titanium nitride coating on unnitrided steel. Optimization of the coating-substrate combination can be achieved by correct control of the plasma-nitriding, surface preparation and ion-plating processes, Graphs, photomicrographs, 35 refs.
Fatigue behaviour of hyperbaric and wet welds. Doyen, J., Castellucci, P. and Colchen, D. Soud. Tech. Conn. J u l y - A u g . 1991 45, (7-8), 4 7 - 5 1 (in French) The capabilities of wet welding as an economically viable alternative to more expensive techniques such as hyperbaric welding were assessed. A numerical modellization and conventional preliminary tests were made to optimize the local geometry of the test samples in terms of the applied stresses and procedural requirements. Samples of E 28-4 steel were produced by hyperbaric and wet welding, using standard filler materials; welding was performed in seawater, at a depth of 5 m, in the horizontal and vertical positions. Fatigue tests on as-welded specimens showed practically identical endurance limits for both underwater welding techniques. It was also shown that the fatigue behaviour is governed almost by local geometry parameters alone. Graphs. 6 refs.
Recommendations for the fatigue design of aluminium alloy structures. Soud. Techn. Conn. J u l y - A u g . 1991 45, (7-8), 1 0 - 3 2 (in French) A general method for the assessment of the limiting state of AI alloy structural members is outlined and rules of the assessment of the endurance of current structural details are proposed. These recommendations concern GTA and GMA welded as well as bolted and riveted joints. Topics include: basic principles, assessment procedure, fatigue loading, stress spectra, fatigue strength, detail classification, improvement of fatigue life and fatigue acceptance testing. Graphs.
The United Kingdom offshore steels research project--phase II HMSO Report No OTH 89 266 160 pp Most of this work was directed towards determining the fatigue endurance of joints, which is expressed in terms of hot-spot stress (HSS) range plotted against number of cycles to failure (N); that is the S-N curve. The topic areas are as follows: thickness effect, corrosion effects, post weld-heat treatment, weld heat treatment, weld improvement techniques, effect of joint geometry and variable-amplitude testing. Graphs. 49 refs.
Int J Fatigue July 1992
General Flexural fatigue behaviour of a cast P100 graphite-fibre-reinforcad 6061 aluminium composite laminate. Dutta I., Mitra, S. and Hansen, R.C. Scr. Metal/. Mater. J u l y 1991 25, (7), 1601-1606 A review studies the flexural fatigue behaviour of cross-plied graphite-reinforced 6061 AI matrix laminates with respect to the effect of fibre orientation and the mechanisms of crack initiation and propagation. Two orientations of the composite were cut. The first (TLT) had the fibres in the two outer plies oriented transverse to the long axis of the specimen, while the second (LTL) had the fibres in the outer plies oriented parallel to the specimen axis. An unreinforced 6061 AI, obtained from Alcoa, and heat treated to duplicate the matrix ageing condition in the composite, was used as a basis for comparison. The fatigue strength of the composites was found to depend strongly on the laminate orientation, and for both TLT and LTL, the longitudinal laminae contributed to the majority of the fatigue lives. Graphs, photomicrographs. 20 refs.
A study of fatigue crack growth in a particulate-reinforced A I - S i alloy at 23 and 220 °C. Healy, J.C. and Beevers, C.J. Mater. Sci. Eng. A Aug. 1991 A142, (2), 1 8 3 - 1 9 2 A study of short- and long-fatigue-crack growth in A356. a cast AI-Si alloy, reinforced with 20% volume fraction of silicon carbide (SIC) particulates, was carried out at 23 °C. Long-crack growth tests were performed at 220 °C. Short-crack growth was observed below the long-crack threshold stress intensity at 23 °C and was dominated by interactions between the crack tips and the SiC particulate. In the long-crack tests at R - 0.1 and R - 0.5, a stress ratio effect on crack growth was observed at 23 °C, which was more marked than that observed at 220 °C. Examination of fatigue fracture surfaces revealed a matrix-dominated mode of crack growth at 220°C compared with that at 23 °C where the SiC particulates played a significant role in the fatigue fracture process. Graphs, photomicrographs. 16 refs.
Remaining fatigue life of old steel bridges. Mang, F. and Bucak, O. Proc. Conf. on Testing of Metals for Structures, Naples, Italy, May 1990 An investigation of a complete bridge structure of the 'museum railway' in the German community of Blumberg and two bridge structures of the 'Deutsche Bundesbahn" is described. The results of component tests are compared with data taken from the literature and other results of similar investigations. Graphs. 13 refs.
A stochastic model for estimating the fatigue life of structural steel details. Castiglioni, C.A. J. Construct. Steel Res. 1991 18, (2), 1 1 1 - 1 3 8 A model is presented that allows the numerical simulation of fatigue crack growth in structural steel details, taking into account the effects of random variations in both the applied loads and the material parameters. A detailed analysis of the numerical code is presented, as well as a discussion of how all the parameters governing the crack growth have been considered and implemented. The calibration needed to simulate correctly the fatigue tests on structural details of practical interest is also discussed. Initially, the effects of the individual parameters of the model are investigated. Next the behaviour of certain typical structural steel details is simulated, and the numerical results are compared with available test data, for both the cases of constant- and variable-amplitude loading. The agreement between the test data and the proposed model has proved to be decidedly satisfactory, although the numerical model can be improved further. Graphs. 35 refs.
Activities in the field of plant life evaluation, life extension and plant improvement. Erve, M. and Bartholome, G. Nucl. Eng. Design J u l y 1991 128, (1), 1 0 3 - 1 1 4 The adequate margin of safety achieved in the as-built condition for a nuclear power plant has to be maintained throughout the whole life of the plant. To ensure this, a systematic evaluation of the lifetimes of safety-related items should be performed in due time in the light of new developments. The results can also be used for the purpose of life extension and licence renewal. Siemens has developed an integral analysis concept by practical experience. The analysis can result in corrective actions with respect to the life extension of plant components and systems or can lead to measures for plant improvement. Examples of the activities performed are given. Materials discussed include austenitic stainless steels, 20MnMoNi5 5, 15MnNi6 3, Inconel 600, Inconel 690 and Incoloy 800. Graphs. 18 refs.
272
Structure and properties of ion-plated aluminium bronze films. Gu, Z., Wang, L. and Yang, L. Mater. Sci. Eng. A J u l y 1991 A140, (1-2), 6 8 7 - 6 9 0 Alum/n/urn bronze films were deposited using the hollow-cathode discharge (HCD) ion plating technique, and their structures and properties were examined and studied. Both film and substrate were QAI 10-4-4 (10wt.% AI, 4wt.% Fe, 4wt.% Ni, balance Cu). The results show that ion-plated AI bronze films have the same structure as the bulk material, but their grains are much smaller than those of the bulk material. The results of X-ray diffraction show that ion-plated AI bronze has more 52 (CugAI4) and K (NiAI) phases than the bulk material, and the residual stresses in the films are compressive. The ion-plated films increase the wear resistance of AI bronze material and its fatigue-resistant properties. Photomicrographs, diffraction patterns. 2 refs. Plasma surface engineering of a l o w - a l l o y steel. Sun, Y. and Bell, T. Mater. Sci. Eng. A J u l y 1991 A140, (1-2), 4 1 9 - 4 3 4 The surface of a low-alloy steel (En40B) has been engineered in the plasma of a glow discharge via plasma nitriding and ion plating of titanium nitride coatings on the nitrided substrates with the purpose of enhancing the surface properties and fatigue strength. The nitriding response of the steel has been accessed by the evaluation of the phase composition, layer thickness, hardness profile, residual stresses, and of the nitrogen and carbon distributions. The wear and fatigue characteristics of the plasma-nitrided steel have been investigated and simple models have been developed to describe the influence of properties such as the depth and strength of the nitrided case on the fatigue limit and the load-bearing capacity of the low-alloy steel. To improve further the tribological properties and load-bearing capacity of the tow-alloy steel, a duplex plasma technique has been developed for surface engineering. This is achieved by plasma nitriding the steel first so as to produce a thick, strong subsurface and then depositing a thin, hard and wear-resistant titanium nitride coating on the nitrided substrata by ion plating. Dry-sliding wear tests demonstrated that the duplex-treated steel, that is the titanium nitride coati ng-nitrided steel composite, not only exhibited enhanced wear resistance over the as-nitrided steel (by a factor of two to eight) but also had a much higher load-bearing capacity than the titanium nitride coating on unnitrided steel. Optimization of the coating-substrate combination can be achieved by correct control of the plasma-nitriding, surface preparation and ion-plating processes, Graphs, photomicrographs, 35 refs.
Fatigue behaviour of hyperbaric and wet welds. Doyen, J., Castellucci, P. and Colchen, D. Soud. Tech. Conn. J u l y - A u g . 1991 45, (7-8), 4 7 - 5 1 (in French) The capabilities of wet welding as an economically viable alternative to more expensive techniques such as hyperbaric welding were assessed. A numerical modellization and conventional preliminary tests were made to optimize the local geometry of the test samples in terms of the applied stresses and procedural requirements. Samples of E 28-4 steel were produced by hyperbaric and wet welding, using standard filler materials; welding was performed in seawater, at a depth of 5 m, in the horizontal and vertical positions. Fatigue tests on as-welded specimens showed practically identical endurance limits for both underwater welding techniques. It was also shown that the fatigue behaviour is governed almost by local geometry parameters alone. Graphs. 6 refs.
Recommendations for the fatigue design of aluminium alloy structures. Soud. Techn. Conn. J u l y - A u g . 1991 45, (7-8), 1 0 - 3 2 (in French) A general method for the assessment of the limiting state of AI alloy structural members is outlined and rules of the assessment of the endurance of current structural details are proposed. These recommendations concern GTA and GMA welded as well as bolted and riveted joints. Topics include: basic principles, assessment procedure, fatigue loading, stress spectra, fatigue strength, detail classification, improvement of fatigue life and fatigue acceptance testing. Graphs.
The United Kingdom offshore steels research project--phase II HMSO Report No OTH 89 266 160 pp Most of this work was directed towards determining the fatigue endurance of joints, which is expressed in terms of hot-spot stress (HSS) range plotted against number of cycles to failure (N); that is the S-N curve. The topic areas are as follows: thickness effect, corrosion effects, post weld-heat treatment, weld heat treatment, weld improvement techniques, effect of joint geometry and variable-amplitude testing. Graphs. 49 refs.
Int J Fatigue July 1992