Rupture properties

Fig. 14. Stress—rupture properties of NiAl alloys and composites compared with superaHoy Renit 80 (77). The Heusler precipitates (ppts) = 50 Ni—25 Al—25X (at. %), where X = a Group 4 (IVB) or Group 5 (VB) element such as Hf. To convert MPa to psi, multiply by 145.

The stress rupture properties of this alloy are shown in Figure 11-6. 

Above temperatures of 900°F, the austenitic stainless steel and other high alloy materials demonstrate inereas-ingly superior creep and stress-rupture properties over the chromium-molybdenum steels. For furnace hangers, tube supports, and other hardware exposed to firebox temperatures, cast alloys of 25 Cr-20 Ni and 25 Cr-12 Ni are frequently used. These materials are also generally needed because of their resistanee to oxidation and other high temperature corrodents. 

Furnace tubes, piping, and exchanger tubing with metal temperatures above 800°F now tend to be an austenitic stainless steel, e.g., Type 304, 321, and 347, although the chromium-molybdenum steels are still used extensively. The stainless steels are favored beeause not only are their creep and stress-rupture properties superior at temperatures over 900°F, but more importantly because of their vastly superior resistance to high-temperature sulfide corrosion and oxidation. Where corrosion is not a significant factor, e.g., steam generation, the low alloys, and in some applications, carbon steel may be used. 

Bismuth Niobium is resistant to bismuth at temperatures up to 560°C but is attacked at higher temperatures and is therefore not considered a suitable container for handling liquid bismuth even under oxygen-free conditions Furthermore, the stress-rupture properties of niobium are significantly lowered when the metal is tested in molten bismuth at 815°C . 

Bismuth Liquid bismuth has little action on tantalum at temperatures below 1000°C " , the rate of attack at 870°C being less than 0.13 mm/y, and exerts not detrimental effects on the stress rupture properties of tantalum at 815°C, but is causes some intergranular attack at 1000°C . 

Bussemer,T., Peppas, N. A., and Bodmeier, R. (2003), Evaluation of the swelling, hydration and rupturing properties of the swelling layer of a rupturable pulsatile drug delivery system, Eur. J. Pharm. Biopharm., 56,261-270. 

The attention of the author has been drawn to an interesting study by Bartenew (Piaste u. Kautschuk, 17, 235 (1970)1 in which the correlation of viscoelastic behaviour and rupture properties is attempted. This deals only with gum elastomers, but when it will be extended to reinforced vulcanizates, it may throw additional light on the subject of this review... 

Tschoegl, N. W., Rinde, J. A., and Smith, T. L. (1970a). Rheological properties of wheat flour doughs. I. Method for determining the large deformation and rupture properties in simple tension. J. Sci. Agric. 21, 65-70. 

Rupture of a tensile test piece may be regarded as catastrophic tearing at the tip of a chance flaw. The success of the WLF reduction principle for fracture energy, G, in tearing thus implies that it will also hold for tensile rupture properties. Indeed, a/, and may be calculated from the appropriate value of G at each rate and temperature, using relations analogous to Eqs. (10.6) and (10.7). The rate of extension at the crack tip will, however, be much greater than the rate of extension of the whole test piece, and this discrepancy in rates must be taken into account (Bueche and Halpin, 1964). 

Enhancing the creep and rupture properties of fibers is undoubtedly beneficial, but explicit goals cannot be set until component testing is done. 

Yun, H.M., J.C. Goldsby, and J.A. DiCarlo. 1995a Environmental effects on tensile creep and stress rupture properties of advanced SiC fibers. Pp. 331-336 in High-Temperature Ceramic-Matrix Composites 11 Manufacturing and Materials Development Vol. 58 in Ceramic Transactions, A.G. Evans and R. Naslain (eds.). Westerville, Ohio American Ceramic Society. 

Reiter has examined the rupturing properties of thin Aims of polymers with relatively high molecular weight and observed that the number density of holes,... 

The tensile creep and creep rupture properties of Prepreg HiPerComp composites have also been evaluated in air for times up to 1000 hours. These data are summarized in... 

The present study aims at investigating the Reaction Bonded Silicon Carbide (RBSC) process to produce porous mullite-bonded SiC ceramics. Wu and Claussen (1991) reported a technique to produce mullite ceramics starting from Al, SiC and AI2O3 powder mixtures. However for the purpose of this study it was decided to use only SiC and Al 03 as the precursor powders with SiC as the major component so that after completion of the reaction the microstructure would be SiC bonded with mullite phase, with no residual alumina. This material was then tested for its mechanical properties like Young s modulus. Modulus of Rupture. Properties of Silicate-based SiC refractories have been reported to a certain extent by Reddy and others. Its potential use as a refractory material has been evaluated by measuring its thermal shock resistance. A sample refractory that has been designed in the... 

For the structural integrity assessment of control plug mockups, 75 thermal shocks have been given so far, based on the preliminary estimation of crack initiation. No visible cracks have been noticed due to the possible statistical variations in the creep-rupture properties. In order to continue the tests, the copper cylinder which was originally provided to simulate the temperatures on the outer shell of mock up, is to be replaced by mild steel cladded with SS. Theoretical analysis has been completed to confirm the use of mild steel in place of copper. 

One of the biggest challenges has been to control the grain size within a narrow range of 45 to 90 microns, in order to meet the conflicting requirements of ultrasonic inspectability and acceptable tensile strength and ductility on one hand and realize the required creep / stress rupture properties, on the other hand, for which coarser grain structure is desirable. 

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