Stainless steels nitrogen, carbon, effect

The polyesterification reaction is normally carried out in stainless steel vessels ranging from 8,000—20,000 L, heated and cooled through internal cods (Fig. 1). Blade agitators revolving at 70—200 rpm ate effective in stirring the low viscosity mobde reactants, which ate maintained under an inert atmosphere of nitrogen or carbon dioxide during the reaction at temperatures up to 240°C. 

Although not recommended, processing requirements may occasionally necessitate storage in partially filled containers. Stainless steel or other containers that can be sealed effectively should be used in this case. After transfer, such containers should be topped with nitrogen gas and sealed. In this case, nitrogen, rather than carbon dioxide gassing, is recommended. The limited solubility of N2 (14 mg/L) compared with COg (1500 mg/L) in wine means that the former remains as a layer on and above the wine s surface for a longer period of time compared with CO2, which rapidly solubilizes. 

Figure 3 presents data showing the wear of carbon materials impregnated with various inorganic materials run against type 304 stainless steel in dry air and in liquid nitrogen. In air these impregnants had little effect on we r in liq-... 

The thermal convection loop is also useful for studying dissimilar-metal mass transfer. The bimetallic loop design shown in Fig. 13 was used by DeVan and Jansen [86] to determine the transport rates of nitrogen and carbon between vanadium alloys and stainless steels in a sodium circuit. Mass transfer rates and carbon and nitrogen effects on mechanical properties were monitored by means of insert specimens in the hot and cold legs. The effects of surface area ratios of the two materials were determined by adding or subtracting insert specimens. 

Barker, M. G. and Frankham, S. A., "The Effects of Carbon and Nitrogen on the Corrosion Resistance of Type 316 Stainless Steel," Journal of Nuclear Materials, Vol. 107, 1982,... 

Although atmospheric corrosion of ferrous metals is related first to the amount of moisture in the air (relative humidity), atmospheric moisture alone has no influence on the corrosion of stainless steel. Of primary importance are the effects of such atmospheric contaminants as particulate chlorides and iron-based dust. Sulfur-based acids will promote corrosion while oxides of nitrogen improve the resistance. Contaminants such as hydrocarbons, ammonia, and oxides of carbon have no effect. 

The relationship between alloying elements and alloy types illustrated in the Schaeffler diagram (Figure 9.1) is an important concept in understanding stainless steels. It has been established that certain elements, specifically chromium, molybdenum and silicon, are ferrite formers. Aluminum and niobium are also ferrite formers, although their effect is dependent on the alloy system. There are also elements that tend to promote the formation of austenite. The most often used are nickel, manganese, carbon, and nitrogen. 

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