Steel alloy structures

Nickel and nickel alloys possess a high degree of resistance to corrosion when exposed to the atmosphere, much higher than carbon and low-alloy steels, although not as high as stainless steels. Corrosion by the atmosphere is, therefore, rarely if ever a factor limiting the life of nickel and nickel alloy structures when exposed to that environment. 

Once properly treated, there are practically thousands of organic adhesive compounds that are available for bonding steel alloys. Epoxies are the most common of structural adhesive for bonding steel. Figure 15.15 shows the effect of humidity on the adhesion of two structural epoxy adhesives used to bond stainless steel. 

Figures 2.4(a),(b),(c) Typical defects occurring in different alloy structures (similar to steel).

FIGURE 18.16 (a) The arrangement of a catalytic converter used to reduce automobile pollution, (b) Cutaway views of several catalytic converters showing different structures for organizing metal catalysts, platinum, palladium, and rhodium on different substrates and supports. A steel-alloy heating element raises the temperature to 400 C in seconds, activating the catalysts and reducing the pollution emitted in the first minutes after the car is started. 

Adequate prediction of the thermal conductivity for pure metals can be made by means of the Wiedeman-Franz law which states that the ratio of the thermal conductivity to the product of the electrical conductivity and the absolute temperature is a constant. This ratio for high-conductivity metals extrapolates essentially to the Sommerfeld value of 2.449 x 10" W f2/K at 0 K, but falls considerably below it at higher temperatures. High-purity aluminum and copper exhibit peaks in thermal conductivity between 20 to 50 K, but these peaks are rapidly suppressed with increased impurity levels and cold work of the metal. Some metals including Monel, Inconel, stainless steel, and structural and aluminum alloys show a steady decrease in thermal conductivity with a decrease in temperature. 

An alternative method of enhancing the properties of steel is to alloy it with another metal, M this combines both interstitial and substitutional alloy structures, with C occupying holes in the Fe lattice, and M occupying lattice sites. Stainless steel is an example of an alloy steel and is discussed further in Box 5.2. For high-wear resistance (e.g. in rail and tram tracks), Mn is alloyed with steel. Other alloy steels contain Ti, V, Co or W, and each solute metal confers specific properties on the finished product. Specific steels are described in Sections 21.2 and 22.2. 

Loe] Loeser, W., VoUemann, T., Metastable Phase Formation in Undercooled Stainless Steel Alloys , Mater. Sci. Forum, 225-221, 27-32 (1996) (Crys. Structure, Experimental, Phase Relations, 18)... 

Supercritical fluid, especially supercritical water (SCW), that is above the thermodynamic critical point of water (374"C, 22.1 MPa), has attracted increasing attention in various applications, such as in supercritical water oxidation (SC WO), in supercritical water gasification (SCWG), and for the continuous synthesis of nanoparticles. The environment of reactors presents a big challenge for structural materials used in the components. Many kinds of materials including stainless steel, alloys, and ceramics have been studied for using in SCW atmosphere. However, the details of the corrosion mechanism of each ceramic in an SCW environment were not fully clarified. 

The base material of construction is a ferritic stainless steel alloy having iron/chrome/aluminum/rare earths. Typical monoliths have between 400 and 600 cpsi, with 0.002-in. wall thickness. The metallic monoliths are heat treated to provide an alumina-rich surface and then the structure is coated with catalysts similar to their ceramic counterparts (10). 

Fuel rod cladding is stainless steel alloy lTT-9, as well as much of the internal core structure [22]. HT-9 is favored in fast neutron applications for its neutron transparency, resistance to radiation damage, and thermal performance. 

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