Surface scale cleaning of titanium sheets by high-pressure liquid and sanding

Fatigue Abstracts 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 SWlY 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).

Micromechanisms of fatigue crack growth and fracture toughness in metal matrix compealtes. Final Report 27 April 1984-15 April 1993.

Applications of new light aluminum alloys - a study of structural main material for advanced fighters.

Davidson, D.L. Southwest Research Institute Report AD-A265 153/7/XAB (1993) 14 pp.

Tiemin, W., Tiecheng, T. and Tinghong, D. Proc. Conf. Light Metals Processing and Applications, Quebec City, Quebec, Canada, 29 Aug.-I Sept. 1993, pp. 677-687

This final report summarizes research in the fatigue and fracture toughness of a large number of materials ranging from metallic and ceramic matrix composites reinforced with ceramic particulates to aluminium, titanium and glass matrix composites reinforced with continuous fibres. The purpose is to summarize and draw conclusions about the state of knowledge of fatigue and fracture mechanisms from the past several years of research sponsored mainly by ONR.

This paper presents applications of new light aluminium alloys in the aircraft industry, briefly introducing applications of 7050 AI alloy with focus on developments and trends of AI-Li alloys. Processing good combinative properties of high strength, good stress-corrosion resistance and moderate fracture toughness (especially for thick section), the 7050 A! alloy can be used in a wide range of products with different shapes and sizes (such as plate forging) under different heat treatment conditions. It has the largest percentage in terms of applications among the materials used on the aircraft. A1-Li alloy series will become the main material for aircraft structure in the future. Their sensitive mechanic problems-fracture toughness, fatigue and corrosion are discussed. This paper also presents two Chinese AI-Li alloys, 8090-AI-Li-I and 2091, by means of analysing chemical composition physicomechanical properties, heat treatment, processing and superplastic ability, fabricating typical structural part specimens for buckling and fatigue tests, assembling a simple door and producing simple complex shape parts by SPF (superplastic forming). This paper also outlines research work and requirements of AI-Li alloys in China, finally anticipating the boundless prospect of applications of AI-Li alloys in advanced fighters beyond the year 2000.

Mechanical preperties of ceramic particulates-reinforced titanium-based compositos produced by blended elemental powder metallurgy.

Hagiwara, M., Emura, S., Kawabe, Y., Arimoto, N. and Marl, S. Proc. Conf. Light Materials for Transportation Systems, Kyongju, Korea, 2023 June 1993, pp. 903-910 Three kinds of conventional titanium alloy (Ti-5AI-2.5Fe, Ti-5AI-13Cr, Ti-6AI-2Sn-4Zr-2Mo) matrix composites reinforced with ceramic particulates such as TiB and TiC were produced by the blended elemental powder metallurgy route. FeB, Cr3C2 and TiB 2 ceramic powders were used as starting powder materials to form these particulates in situ in the matrix. The composites showed improved Young's modulus, and tensile creep, and highcycle fatigue strength over those for the unreinforced matrix alloys. Graphs, photomicrographs, I0 ref.

Investigation of the thermal fatigue behavtours of chemically deposited cobalt-phosphorus alloy on the hot work die steel.

You, X . Q and Zhu, S.F. Mater. Mech. Eng. (China) (1993) 17 (1), 29-32, 50 (in Chinese)

Influence of thermomecbanical processing on the tensile and fatigue properties of a SiC part/de rehiforced aJuminlum alloy.

Harris, S.J., McCall, LR. and Huang, Z.W. Proc. Conf. Developments and Applications of Ceramics and New Metal Alloys, Quebec City, Quebec, Canada, 29 Aug.-2 Sept. 1993, pp. 117-126 The addition of small (3 p.m) silicon carbide particles to an AI-Cu-Mg (2124) alloy can improve its strength properties significantly. Such materials have been tested in the naturally aged (T4) condition; however, with the application of a cold stretch prior to ageing, the yield strength of the composite is increased further. Fatigue tests have been carried out on the composite in the T4 and in the stretched and aged (T3) condition. This has demonstrated an improvement in fatigue strength in both conditions well above that of the unreinforced alloy. A TEM investigation has revealed that dislocation substructures set up during processing favourably influence strength and fatigue performance. Fractographic studies have been used to investigate fatigue crack initation and growth behaviour in these materials. Graphs, photomicrographs, 5 ref. Fatigue behavior of alumina short fiber reinforced aluminum ahoy at room and higher temperatures.

Tanaka, T., Yamamoto,S., Kobayashi, Y. and Nakayama, H. J. Sac. Mater. Sci. Jpn (June 1993) 42 (477), 689-695 (in Japanese) As a first step in the study on the fatigue mechanism of fibre and/or particlereinforced aluminium alloys, a series of fatigue tests and fatigue crack growth tests on an alumina short fibre reinforced AI alloy (A6061) in push-pull load conditions were carried out. The results indicated that the fatigue failure of this fibre-reinforced AI alloy was governed by two main mechanisms: one was a debonding of the fibre and matrix induced by the localized plastic strain, depending on the mismatch of elastic constants, and the other was the failure of the matrix induced by the accumulation of fatigue damage around the bond interface. In the higher applied stress range, and at room and relatively lower temperatures, the former mechanism is predominant, hut in the lower stress range, and consequently in the longer-life region, the latter mechanism plays a main role, and this trend becomes more dominant with each increase in temperature. Graphs, photomicrographs, 16 ref. 0142-1123/94/070513-07 © 1994 B u t t e r w o r t h - H e i n e m a n n Ltd

Thermal fatigue is one of the main failure forms of hot-work die. Co-P alloy has been plated on 3Cr2W8V steel. The test of 25-680 °C thermal fatigue has been made by means of self-made and self-strained machine. The thermal fatigue crack initiation and propagation have been observed under MIC and SEM. The effect of heat treatment on the thermal fatigue resistance of this plating has been studied. The thermal lives of Co-P plated 3Cr2W8V steel with those of 3Cr2W8V steel without Co-P plating are compared. These results provide a theoretical basis for the further use of Co-P electroless plating in hot-work dies. Diffraction patterns, graphs, photomicrographs, 7 ref. Low cycle fatigue life of ceramic-sprayed Cr-Mo steel.

Sonoya, K., Tomisawa, Y., Kitagawa, M. and Kayigaya 1. Jr+Sac. Mater. Sci. Ipn (Sept. 1993) 42 (480), 1077-1082 (in Japanese) Low-cycle fatigue tests were performed at RT and elevated (673 K) temperatures for ceramic sprayed 1Cr-0.5Mo steels (STBA22). The fatigue properties of ceramic-sprayed steels and the mechanism of fatigue-fracture were discussed. The main results obtained are as follows. (1) The fatigue life of the ceramic-sprayed steel at 673 K was slightly longer than the life at RT, where it was shorter than those of the base metal at RT and elevated temperatures. (2) The crack initiation in the ceramic layer occurred at a significantly early state of fatigue of the coated steel. As the strain range became smaller, the crack initiation life of the ceramic layer became longer. (3) The fatigue-fracture process of the coated steel is considered as follows. At an early stage of fatigue, a fatigue crack is initiated at the surface of the ceramic layer and propagates quickly to the metal layer. The propagating fatigue crack through the ceramic layer continues to grow into the substrate. Graphs, photomicrographs, 12 ref. Surface scale cleattlng of titanium sheets by high-pressuru liquid and sanding.

Xia, J.P., Ma, Y.X., Wang, B.A. and Luo, S.L. Xiyou Jinshu Cailiao yu Gongcheng (Rare Metal Materials and Engineering) (1993) 22 (2) 66-72 (in Chinese)

Not only the fundamental principle and technique of using high-pressure liquid and sanding to clean the surface scale of titanium sheets but also the design ideas, structure characteristics, and difficult points of technique are

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described in detail. It was shown that the structure was reasonable, all the design demands of properties had been met, and the quality of cleaning surface scale was similar to the acid-corroded ones according to the analysis of craft parameters of operation for the completed equipment. For the mechanical properties of the cleaned Ti sheets, the fatigue strength was lower and the others were unchanged if compared with acid-corroded ones. 12 ref. Fatigue properties of brazed aluminium alloy joints

Sato, S., Sukimoto, M., honaga, S. and Honda, 1". J. Jpn Inst. Light Met. (Sept. 1993) 43 (9), 478-483 (in Japanese) The fatigue life distribution of the brazing butt joint consisting of D712.0 and A6063 alloys was analysed statistically, in order to evaluate reliability and strength characteristics of an air intake manifold made by brazing joint of cast and wrought aluminium alloys. Obtained results are summarized as follows. Fatigue life distribution of the brazing joint is scattered according to the normal distribution. Scatter of fatigue life seems to be influenced by brazing defect ratio, filter metal microstructure, and joint force with base metals. Graphs, photomicrographs, 6 ref. Modelling the faff~gue of aluminum spot welds.

Thornton, P.H., Krause, A.R. and Davies, R.G. Proc. Conf. Light Metals Processing and Applications, Quebec City, Quebec, Canada, 29 Aug.-1 Sept. 1993, pp. 601-614 Models based upon a modified nominal axial load, stress intensity factor and stress index that have been suggested for correlating the fatigue behaviour of steel spot welds are applied to fatigue data for overlap shear spot welds in several aluminium alloys. For the long fatigue life regime (106 cyles) the stress range and stress intensity factors are significantly less than those for steel spot welds. The values of these quantities for the AI alloys varied with heat treatment condition, but not in any systematic manner with simple mechanical strength. A finite element model based upon the presumed mechanical properties of the wrought base metal and chili chest weld nugget indicated that weld fracture rather than base metal fracture would occur in the short life, high load fatigue regime, in accordance with observation. Graphs, maps, l0 ref. The fatigue of spot-welded aluminum alloys.

Krause, A.R., Thornton, P.H. and Davies, R.G. Proc. Conf. Light Metals Processing and Applications, Quebec City, Quebec, Canada, 29 Aug.-1 Sept. 1993, pp. 589-600 The fatigue response of spot-welded aluminium alloys in overlap shear has been investigated for both heat-treatable and non-heat-treatable alloys. For the non-heat-treatable AI alloy, welding conditions were investigated which affected both the nugget diameter and fatigue failure modes. For the heattreatable AI alloys, the welding conditions were held constant to maintain constant nugget diameter but the base material strength was varied from the O temper to the T6 temper. Fatigue testing was performed on samples welded subsequent to heat treatment, and for the non-heat-treatable alloy test geometries were varied. The metallography of the weld nuggets as well as the fracture modes observed is discusssed. Graphs, 11 ref. Effect of specimen geometry on fatigue of welded joints.

Guha, B. Eng. Fract. Mech. (Sept. 1993) 46 (1), 35-39

Reports indicate that the joint geometry and loading configuration affect the crack growth behaviour of specimens. In an attempt to study the above effect, three specimen geometries are selected: cruciform joint under tension (CJT), side end notch under tension (SENT) and under three-point bending (SENB3)Ioad. Results show that all three geometries have different fatigue strength and fracture mechanics parameters, although their weld-metal chemistry and mechanical properties are the same. Further tests are needed to establish this relationship quantitatively. Carbon manganese steel weldments are tested. Graphs, 9 ref. Cyclic neor-tip fields for fatigue cracks along metal/metal and metal/ceramic interfaces.

Woelt]en, C., Shih, C.F. and Suresh, S. Acta Metall. Mater. (Aug. 1993) 41 (8), 2317-2335 Finite element analyses were conducted with the objective of determining the cyclic near-tip fields ahead of a stationary tensile fatigue crack lying along the interface between two dissimilar solids. The model systems analysed are (i) a metal/metal bimaterial whose components have the same elastic properties but different plastic deformation characteristics, and (ii) a metal/ ceramic bimaterial. In both cases, monotonic loading to the peak tensile load results in a predominantly mode I field ahead of the crack. However, unloading in one or both components of the bimaterial with prior plastic deformation generates mixed-mode conditions at the crack tip. The mode mixity persists during a significant portion of the next loading phase and is gradually removed upon reloading to the peak stress. The cyclic plastic zone size directly ahead of the fatigue crack is approximately one-fifth the size of the monotonic plastic zone. The residual compressive stresses within the cyclic plastic zone are computed. The implications of reversed yielding and mixed-mode near-tip fields to constant-amplitude and variable-amplitude fatigue fracture are discussed. Graphs, 36 ref.

514 Fatigue, 1994, Vol 16, October

Fatigue life prediction for plate girder specimens with four types of vertical stiffener connections.

Sakano, M., Mikami, L and Yonemoto, E. Technology Reports of Kansai University (Mar. 1993) (35), 277-284 Fatigue crack propagation analysis is performed to estimate the fatigue life of four types of vertical stiffener connections in plate girders. The fatigue life of three types of connections with fatigue cracks developed from the turn-round fillet weld toe in steel (JIS SM490A) welded joint can be estimated by using two-dimensional finite element models reflecting the configuration of fillet weld toe in each detail. The other type of connection with fatigue cracks initiated at the intersection of weldments requires three-dimensional finite element models simulating the stress concentration at the intersection. Graphs, 8 ref. Simulation analysis of fatigue design curves for Shlnkansen steel bridges.

Sakano, M., Mikami, 1. and Nishimura, T. Technology Reports of Kansai University (Mar. 1993) (35), 267-276

Fatigue design curves for steel railway bridges are investigated through fatigue crack propagation analysis using variable-amplitude stresses generated by a computer simulation of Shinkansen train loading. It can be found that the cut-off limit for variable-amplitude stresses in Shinkansen bridges varies widely with the type of structural members. Graphs, 4 ref. Analysis for size effects on fatigue strength of out-of-plane gusset joints.

Sakano, M., Mikami, 1. and Arai, M. Technology Reports of Kansai University (Mar. 1993) (35), 247-256

It is necessary to investigate the low-stress and long-life fatigue behaviour of out-of-plane gusset joints made of thick steel plates. Therefore through fatigue crack propagation analysis applying the fracture mechanics concept, and the effects of the size of the main plate and attachments on the fatigue strength of out-of-plane gusset joints are investigated. The fatigue strength of out-of-plane gusset joints decreases in tl and t2, when these are identical. Graphs, 14 ref. Fatigue in single crystal nickel superailoys. Technkni Progress Report, 16 March-15 April 1993.

DeLuca, D.P. and Annis, C. United Technologies Report, AD-A266 ll6/3/XAB (1993) 6 pp This programme investigates the seemingly unusual behaviour of single-crystal airfoil materials. The fatigue initiation processes in singie-crystal materials are significantly more comphcated and involved than fatigue initiation and subsequent behaviour of a (single) maerocrack in conventional, isotropic materials. To understand these differences is the major goal of this project. The development of stresses and their distribution in two-phase alloys during cyclic loading.

Li, Z., Luo, J. and Li, Y. Fatigue Fract. Eng. Mater. Struct. (July 1993) 16 (7), 781-794 A finite element program calculates the cyclic behaviour of the individual component phases of a multiphase material using a master curve observed in uniaxial cyclic stress tests. The fatigue behaviour of the two-phase alloys was characterized by visualizing the evolution of the phase stress (denoted by an average effective stress and a hydrostatic stress) during cyclic loading. The evolution procedure shows a unique fatigue behaviour of the in situ component phases, which differs from that observed in uniaxial or multiaxial fatigue tests of the single-phase material. The fatigue damage on a microstructural scale was identified by the distributions of the plastic strain accumulated during cyclic loading and the stress triaxiality in the component phases. Pure iron, 19Mn5 and 65Mn were studied. Graphs, photomicrographs, 23 ref. Shear connection of composite beams with profiled steel sheeting and dynamic loading (Tragerverbund unter dynamischer Belastung bei Verwendtmg yon Profllblechen).

Bode, H. and Becker, J. Stahlbau (July 1993) 62 (7), 195-201 (in German) Dynamic tests with headed studs as shear connectors of composite beams with profiled steel sheeting have been carried out in the laboratory for constructional engineering of the University of Kalserslautern, Germany, to determine the fatigue strength. The test series and the results are described and a design procedure is explained. Graphs, 19 ref. The effect of oxidizing environments on high temperature fatigue failure of 3CR12 alloy.

Aghion, E. and Ferreira, J. Can. Metall. Q. (Oct.-Dec. 1993) 32 (4), 369-374 3CR12 alloy is a titanium-stabilized chromium containing corrosion-resisting steel which was developed as a cost-effective alternative material of construction in applications where tow-carbon and other structural steels have proved to have an inadequate combination of corrosion resistance and mechanical properties. Lately the use of 3CR12 was considered for components in the power generating and chemical industries operating under creep-fatigue loading conditions and oxidizing environments. A systematic study was conducted to evaluate the effect of an oxidizing environment, in the form of an oxygen-containing atmosphere, on the creep-fatigue failure of 3CR12 at 600 °C. The tests consisted of a creep tensile cycle and a plastic compression cycle and were conducted according to the CP mode of the strain range partitioning method. The strain ranges varied from 0.2% up to 0.4%. The results showed that the fatigue lives of 3CR12 were greater in an atmosphere containing up to 20% O than in an inert argon atmosphere, indicating an adequate oxidizing resistance of the alloy under the cyclic loading conditions