The fact that the microstructure of steel depends on its composition and the heat treatment given to it has been heavily exploited in the design of steel for power plant applications. To obtain a steel that can function at the higher temperature where power plants operate without failure for extended life, heat treatment is needed to produce fine and highly stable dispersion of carbides, nitrides, and intermetallic compounds in the microstructure of the material. A significant contribution also comes from solid solution strengthening by substitutional solutes. We review here various types of phases, microstructures, functions, and interacting effects of the various alloying elements in the design of steel for modern power plant application.

The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated), E 308-16(lime-titania coated) electrodes, and TIG welded joints fall within the range of 1.5 ≤ Cr eq. /Ni eq. ≤ 1.9 and solidified with a duplex mode and were found to be resistant to solidification cracking. The E 308-16 weld metal had the greatest resistance to solidification cracking. Joints produced from E 310-16 had Cr eq. /Ni eq. ratio < 1.5 and solidified with austenite mode. It was found to be susceptible to solidification cracking. E 312-16 produced joints having Cr eq. /Ni eq. ratio > 1.9 and solidified with ferrite mode. It had a low resistance to solidification cracking.

The need for electricity supply has increased tremendously in recent time thereby necessitating an improvement in the efficiency of steam power plant. A greater efficiency leads to a saving in fuel for a given electricity output with a consequential reduction in the rate at which damage is done to the earth's environment. This paper looks at the physical metallurgy theories and parametric models that have been the bases in the design of steel for power plant applications.

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A model has been derived for periodic analysis of the quantity of water evaporated during thermo-processing of clay designated for production of oven refractory. The model; γ = exp lnt 1.3 2.9206 shows that the quantity of evaporated water during the drying process is dependent on the drying time, with the evaporating surface being constant. It was found that the validity of the model is rooted on the expression lnγ = (lnt/Logβ) N where both sides of the equation are correspondingly almost equal. The maximum deviation of the model-predicted quantity of evaporated water from the corresponding experimental value is less than 19% which is quite within the acceptable deviation range of experimental results. Water evaporation rate as obtained from experiment and derived model were evaluated to be 0.0536 and 0.0337g mins-1 respectively.

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