This section contains abstracts of selected articles, technical reports, dissertations and patents ~oncerned with fatigue. It is prepared in collaboration with Materials Information, a joint service of The Institute of Metals and ASM International. Readers wishing to obtain the full text of articles abstracted here should contact either: The Institute of Metals, 1 Carlton House Terrace, London S W l Y 5DB, UK, or: ASM International, Metals Park, OH 44073, USA (not International 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). Composites Study o f t h e interface end its effest on mechanical properties o f continuous g r a p h i t e fibre-reloforced 291 e l u m i n i u m . Nayeb-Hashemi, H. and Seyyedi, J. MetelL Trans. Apr. 1989 A 29A, (4), 727-739 The formation of fibre/matrix interfecial reaction zone and its impact on mechanical properties of Gr/2Ol At composite (41 voL % fibre) was evaluated in the as.received condition and after heat treatment in vacuum at 450, 500 and 545°C for one day, and at 545°C for one week. After heat treatment, the microstructures of matrix and interface were studied by transmission electron microscopy. This study revealed the presence of interfecial constituents AI4, C3, AI4, O4C and TiB2. The mean fibre/ matrix reaction zone thickness showed an increase with increasing heat treatment temperature and time. The effects of heat treatment on interfecial shear strength, monotonic and cyclic tension/compression properties were evaluated. The results show that the interfecial shear strength not only depends on chemical reaction but also depends on the thickness of the reaction zone. An increase in reaction zone size reduces mechanicet bonding considerably (thermal-induced stresses). The growth of reaction zone was very detrimental to monotonic and cyclic tension/ tension fatigue behaviour. The mechanism of failure in tansion/tension fatigue was the initiation of cracks at the interface and their subsequent propagation in the matrix. It was concluded that the reaction zone was the controlling factor in tension/ tension fatigue, in contrast, the results showed that compressional fatigue was matrix-dependent and was only slightly sensitive to the size of the fibre/matrix interfecial reaction zone. 31 refs.
Screening o f m e t a l - m a t r i x c o m p o s i t e s using ultrasonic C-scans. Johnson, W.S. J. Compos. Technol. Res. Spring 1989 11, (1), 3 1 - 3 4 How ultrasonic C-scens can be used to find some types of defects in continuous fibre reinforced metal-matrix composites (sO B/6061 AI) composites is shown. These defects are then related to the fatigue behaviour and fracture location of each inspected specimen. The C-scan technique was used to determine the relative amount of defects in B/AI composites. The defects were primarily identified as gaps in the fibre spacing. Those specimens with higher defect densities had shorter fatigue lives, lower fatigue endurance limits, and greater reductions in the elastic unloading modulus (that is, stiffness) because of fatigue cycling. This type of data could be used to set accept/reject levels for a composite panel based on C-scan indications. 8 refs.
Corrosion FFT analysis o f polarization current f l u c t u a t i o n dudng corrosion f a t i g u e on HT60 h i g h - s t r e n g t h steel. Ono, M., Kayano, Y., Shimojo, M., Ht"go,
Y. and Nunomura, S. Tetsu-to-Hagane (J. Iron Steel Inst. Jpn.) Jan. 1989 75, (1), 113-120 (in Japanese) During potentiostatic corrosion fatigue tests, fluctuation of polarization current which is synchronized with the cyclic tansion--compression loading was observed. This current fluctuation means that the corrosion rate was accelerated by the cyclic loading. Using Fourier transformation, the current component of this acceleration, which is synchronized with the cyclic loading, was separated from the polarization current. This component of the current is termed 'stress synchronized polarization current (SSPC)' and is compared with the fatigue life. Corrosion fatigue tests for high strength steel HT60 was carried out potentiostatically in artificial seawater solution and in borate solution under conditions of bend type specimens. In the artificial seawater, with the exception of the potential range where prominent general corrosion of hydrogen embrittlement occurred, there was a good correlation between SSPC and the fatigue life. Under the potential where SSPC was low, corrosion fatigue damage was also small and fatigue life was longer. This correlation is clear in the borate solution in which the passive film formed. The result suggests that the SSPC, which can be measured at the early stage of fatigue tests, is useful to estimate the corrosion fatigue damage quantitatively. 27 refs.
Corrosion resistance and f a t i g u e s t r e n g t h o f stainless steels for chemical tankers. Yajima, H., Sueoka, H., Zerna, M., Mort, T. and Kabate, 7". Mitsubishi Heavy Ind. Tech. Rev. Oct. 1988 25, (3), 185-190 The characteristics of stainless steels for chemical tankers were investigated in order to increase the reliability of stainless steel tank construction of chemical tankers. The corrosion resistance and the fatigue strength are described among the many
Int J Fatigue September 1989
characteristics of stainless steels, which are key factors to get the satisfactory qualities. The complicated parameters of corrosion in various conditions ere clarified respectively and the corrosion resistance against the typical corrosive cargoes is evaluated, while it is understood that the tank cleaning operations influence the corrosion of stainless steel tanks, especially in some kinds of cargoes, such as concentrated sulphuric acid. The fatigue strength of butt welded joints and fillet welded cruciform joints of stainless steel is obtained experimentally. On the basis of research and development, more reliable chemical tankers have been designed and constructed. 10 refs. The influence o f t h e mechanical test conditions on the corrosion f a t i g u e heheviour o f euatenitic stainless steel in chloride solutions. Magnin, T.,
Desjardins, D. and Puiggali, M. Corros. Sci. 1989 29, (5), 567-576 The corrosion fatigue behaviour of the 316L alloy in chloride solutions is analysed and compared to the stress corrosion cracking behaviour of the same alloy in the same electrochemical conditions. The kind of corrosion fatigue test (cyclic tensile stress, tension-compression strain) is shown to have a very sensitive effect on the resulting damage. The tansion-compression test is much more severe than the cyclic tensile stress and induces damage which can occur even if stress corrosion cracking is not observed. 13 refs.
Corrosion fatigue behsviour o f 13Cr m a f t e n s i t i c stainless steels in 3% NaCI s o l u t i o n w i t h special reference t o t h e i r intergranuiar corrosion susceptibility. Osake, T., Ishikawa, Y. and Mukai, Y. Teteu-to-Hagane (J. Iron Steel Inst. Jpn.) Mar. 1989 75, (3), 523-528 (in Japanese) Corrosion fatigue tests of 13Cr rnartensitic stainless steels in several tempered states were carried out in 3% NaCI solution at room temperature, and the effect of metallurgical variables on corrosion fatigue strength at 107-10s cycles was investigated. The corrosion fatigue strength, ~ , decreases monotonicetly with the loading cycle. At 10s cycles, owc decreases to 50 MPs for some tempered states. In the high cycle region, owc strongly depends on the tempering conditions, and owc of the steels sensitive to intergranular corrosion was relatively low because of the formation of deep pits. The apparent stress intensity factor for corrosion fatigue cracking, Kcf, is about 1.6-2.5 MPa ~/m at ~07--109cyc|es and independent of tempering conditions. The rate determining process for corrosion fatigue life under high cycle and low stress conditions appears to be that of pitting corrosion. One effective method to increase corrosion fatigue strength may be careful selection of the tempering conditions in which the Cr depleted zone is not formed. 22 refs. Fretting corrosion. Collin, G., Guerin, J.-J., Baratto, G. and Mongis, J. CETIM INf. Oct. 1988 107, 4 7 - 5 2 (in French) Fretting or contact corrosion results from two surfaces oscillating against each other, thus causing wear. This wear can lead to eventual fatigue failure. Examples cited of failure due to fretting corrosion are a medium carbon steel crankshaft, a cast AI alloy gear case, and two alloy steel shafts (eg 17-4 PHi for centrifugal compressors. Prevention by modification of the contact area, surface coatings and material changes is suggested. The effects o f corrosion on t h e reliability o f steel girder bridges. (Dissertation). Kayser, J.R. Dies, Abstr. Int. Nov, 1988 49, (5), p p 205 The objective is to develop a corrosion damage model to measure and predict the performance of corroded steel bridges. The damage model is developed from information concerning the type, location, pattern, and rate of corrosion occurring on a bridge. The most important form of corrosion, general surface loss, is considered. Additional investigation is given to corrosion fatigue. The other forms of corrosion which occur (galvanic, pitting, crevice, and stress) are identified and discussed. Structural reliability theory is used to determine the probable distribution of corrosion, loss, member resistance, and structural safety. The resistance modes of bending, shear, and bearing are treated as a series system. The system reliability is calculated from the component reliabilities and correlations of the resistance modes. The safety of the individual modes and of the system is measured in terms of the reliability index, using a normal variable formulation. The rating of a corroded bridge is based on the standard procedures set forth by AASHTO. A comparison is made between the safety and capacity of simple span steal girder bridges of differing lengths. Each bridge is considered with and without a web bearing stiffener at the support. Different types of environment are also studied. The parameters which make up the corrosion damage model are investigated using sensitivity analysis. The investigation shows that a marine environment, with salt contamination, has an extremely detrimental effect on bridge performance. The rural and urban