Fatigue Abstracts Fatigue behaviour of austenitic stainless steel sheets for rnllcars. Budano, S. and Florio, G. Proc. Conf. Processes and Materials." Innovation Stainless Steel, Florence, Italy, 11-14 Oct, 1993, Vol. 1, pp 1.277-1.284 Use properties of interest for application in railcars of cold-worked austenitic stainless steel sheets of AISI 301 LN and AISI 304 have been evaluated. Utilization of these products is considered to be convenient either for railcar manufacturers or for railway companies because the ever-higher costs for corrosion protection can be significantly limited, and maintenance expenditures as well as shut-down losses are avoided. Spot weldability and fatigue behaviour of spot-welded lap joints made of cold-rolled sheets of AISI 301LN and 304 of different thickness have been studied. The experimental activity showed the suitability of stainless steel sheets to be easily spot welded. The useful range of welding parameters to obtain optimized features of welded lap joints was assessed. Fatigue properties of smooth and folded specimens, and of spot welded lap joints of different geometry have been determined. The result obtained can be profitably used in the design and manufacture of stainless railcars. Graphs, 5 ref. Mechanical properties of austeniti¢ and duplex stainless steel. Nordberg, H. Proc. Conf. Processes and Materials: Innovation Stainless Steel, Florence, Italy, 11-14 Oct. 1993, Vol. 2, pp 2.217-2.229 Mathematical relations between chemical and microstructural parameters and mechanical properties, yield strength, flow stress, tensile strength and fatigue limit are presented. The relations are able to predict properties for a wide range of austenitic and duplex stainless steels. Graphs, 26 ref. Effect of nickel on high-temperature properties for ferritic stainless steel. Fujita, N., Ohmura, K., Kikuchi, M., Suzuki, T., Funaki, S. and Hiroshige, L Proc. Conf. Processes and Materials: Innovation Stainless Steel, Florence, Italy, 11-14 Oct. 1993, Vol, 2. pp. 2.197-2.202 Ferritic steels generally have less strength at high temperature than austenitic steels. On the other hand a ferritic steel has a longer thermal fatigue life than an austenitic steel because of a lower coefficient of thermal expansion for ferritic steels. For this reason, some conventional ferritic stainless steels were used for automotive exhaust manifolds. But exhaust gas temperature tends to be high to increase engine horsepower and improve fuel economy. Materials with better heat resistance are needed for this use. In the present study, the improvement of proof strength at high temperature for ferritic stainless steel to achieve longer thermal fatigue life was the centre of the investigation. It was proven that one of the most effective methods to improve high-temperature strength is to increase the initial solid solution amount of niobium. In addition, the high-temperature strengthening mechanism using Nb for ferritic stainless steel is discussed. Graphs, photomicrographs, 4 ref. Fatigue behaviour of welded austenitic steels. Mang, F., Bucak, O. and Koch, E. Proc. Conf. Processes and Materials: Innovation Stainless Steel, Florence, Italy, 11-14 Oct. 1993, Vol. 2, pp. 2.139-2.148 Austenitic steels have been applied not only in the chemical industry but also in various dynamically loaded structures. Steel chimneys, sewage treatment, steel and hydraulic structures and the construction of transportation systems can be considered as the most important fields of application. Regarding these constructions, the four most important basic notch cases include butt welded joints, cross joints (with fillet weld), members with longitudinal rib and members with transverse rib. Experimental investigations regarding their fatigue behaviour cannot be found in the literature. Individual series of tests on welded specimens in the low-cycle fatigue range are available, but those in the high-cycle fatigue range are not known yet. In practice, therefore, these cases are treated like those of mild steel application. In this paper, results of the first experimental investigations are presented (for X6CrNiMoTiI7122) of mild steel. Based on these investigations, the conception of a future research project regarding the fatigue behaviour of welded austenitic stainless steels in corrosive environment under service loads is submitted for discussion. Graphs, 16 ref. Research on strength and toughness of the microanoyed medium carbon steel 40SiMnV. Sun, Z.B. and An, Y.Z. Iron and Steel (China) (1994) 29 (20), 57-61, 45 (in Chinese) The hot-working effects on the microstructure, ordinary mechanical properties, fracture toughness, and fatigue feature of the microalloyed medium carbon steel 40SiMnV are discussed. It is found that the strength, fatigue limit, and high-cycle impact resistance with low energy of this steel are similar to that of 40Cr steel under the state of quenching and tempering, but the toughness is much lower than that of 40Cr. The strength and toughness of microalloyed medium C steel could be controlled by the quality of pearlite or pro-eutectoid ferrite, the grain size, and the precipitating ability of pro-eutectoid ferrite, while the microstructure factors of pro-eutectoid ferrite depend on the prior austenite grain diameter, cooling rate. and hot-working method (rolling, forging, and normalizing). The mathematical model between the mechanical properties of microstructure factors could be established. The property characteristic and the application of microalloyed medium C steel are discussed; the optimizing principles of hot-working technologies by which better overall mechanical properties could be obtained are proposed. Graphs, photomicrographs, 6 ref.
A general fatigue theory and its application to out-of-phase cyclic loading. Ellyin, F. and Xia, Z. J. Eng. Mater. Technol. (Trans. ASME) (Oct. 1993) 115 (4), 411-416 Results of an experimental investigation of a constant-amplitude, fully reversed biaxial tension-compression out-of-phase cyclic loading are presented first. An energy-based fatigue theory is extended to include non-proportional (out-of-phase) cyclic loading. Finally, a constitutive model is presented to predict the cyclic multiaxial stress-strain response, and to calculate the energy-based damage parameter. A general theory, applicable to uniaxial, proportional, and non-proportional multiaxial cyclic fatigue is presented. The predicted results are in fairly good agreement with the constant-amplitude test data. A few uniaxial fatigue tests and an out-of-phase cyclic test are required to specify material constants of the theory. Graphs, 14 ref. Fatigue of AZ91E-T6 cast magnesium alloy. Goodenberger, D.L. and Stephens, R.I. J. Eng. Mater. Technol. (Trans. ASME) (Oct. 1993) i15 (4), 391-397 Room-temperature fatigue behaviour of AZ91E-T6 cast magnesium alloy was studied. Whether commonly used models that depict fatigue behaviour are applicable to this cast alloy was determined. Axial strain-controlled fatigue behaviour using cylindrical specimens was employed to determine low-cycle fatigue behaviour with strain ratios R = ¢mi~/e,,~ 0, - 1 , and -2. The conventional log-log total strain low-cycle fatigue model properly represented the R = - 1 axial fatigue data. Significant mean stress relaxation occurred for all R = 0 and - 2 axial fatigue tests. However, for the smaller strain amplitude tests with R = 0, sufficient mean stresses were retained such that fatigue life was reduced. The mean stress/stresses had little influence on the cyclic stress-strain curve, which exhibited cyclic strain hardening. Mean stress effects were analysed using the Morrow, SWT and Lorenzo-Laird models and similar, but often non-conservative, calculations resulted. Region I and If fatigue crack growth behaviour was determined using C(T) specimens with load ratios R = Pmin/Pm~ = 0.05 and 0.5. Values of AKthand (AKth)e ff were less than 1.5 MPa m i and the Paris equation slopes were between 3.3 and 3.9. Quasi-cleavage was predominant for both fatigue crack growth and final fracture regions. The commonly used low-cycle fatigue and fatigue crack growth models appear to reasonably represent most of the results with this AZ91E-T6 cast Mg alloy. Graphs, 12 ref. Application and verification of fatigue life calculation methods for AZ9IE-T6 cast magnesium alloy under variable amplitude loading. Perov, S.N, Stevens, R.I. and Ogarevi, V.V. J. Eng. Mater. Technol. (Trans. ASME) (Oct. 1993), 115 (4), 385-390 The applicability of commonly used fatigue life calculation methods for variable amplitude loading with sand cast AZ91E-T6 magnesium alloy using notched 'keyhole' specimens was determined. Commercially available fatigue life calculation software packages were used to calculate the fatigue crack initiation life (1 mm crack) and fatigue crack growth life corresponding to the experiments. The resulting correlation between experimental and calculated fatigue lives ranged from good to poor, and from conservative to nonconservative, depending on the analysis method used. It was shown that these fatigue life calculation methods can be used with this sand cast Mg alloy but with certain apprehension. Graphs, 13 ref. The use of classification zones for fatigue behavior in steels. 11. Weiss, M.P. J. Eng. Mater. Technol. (Trans. ASME) (Oct. 1993) 115 (4), 380-384 The basic idea of classification of the fatigue regime is implemented, using updated fatigue studies, and the result is a new and updated diagram. Numerous studies on fatigue damage and fatigue crack propagation dealt with these problems either by the cumulative damage approach, or by using crack propagation equations based on linear elastic fracture mechanics. Although these two approaches are not compatible, each is useful for predicting fatigue behaviour with acceptable scatter, but only within defined limits. This study updates the fatigue diagram, which classifies different combinations by stresses and crack lengths in a given specimen, as zones in which different fatigue evaluation criteria govern. The whole fatigue regime is divided into six zones, which fit known and new prediction methods. For the more problematic zone, where the stress amplitude is higher than the fatigue limit, and the stress intensity factor range is higher than the threshold, a superposition of two prediction procedures is shown to match closely to test results in AISI 4XXX types of steel specimen including 4130. The fatigue diagram is shown to be a useful tool for dealing with real-life, fatigue design problems. The threshold crack length is reintroduced, and directions for additional studies are indicated. Graphs, 16 ref. Constitutive equations for the thermomechanical response of Rene. If. Effects of temperature history. Bhattachar, V.S. and Stouffer, D.C. J. Eng. Mater. Technol. (Trans. ASME) (Oct. 1993) 115 (4), 358-364 The unified constitutive equations for Rene 80 developed by Bhattachar and Stouffer (1992) are used to predict the thermomechanical fatigue (TMF) response of a nickel base superalloy Rene 80 between 649 and 1093°C. Predictions using these equations suggest that temperature history effects are significant during TMF, and that the TMF response of Rene cannot be predicted completely using only isothermal parameters. It is postulated without metallurgical observations that the two deformation mechanisms in Rene 80, planar slip at low temperatures and dislocation climb at high temperatures, produce characteristic microstructures which interact under unisothermal conditions to produce extra hardening that is not present during isothermal deformation. A state variable approach has been used to model this interaction. The non-isothermal model with temperature history effects