The effect of thermomechanical controlled processing (TMCP) on structural refinement and enhancement of properties of a low carbon Cu-B high strength low alloy steel has been investigated. Thermomechanical processing was carried out according to various schedules. A few hot rolled bars were solution treated, quenched and aged at 600uC to study the effect of precipitation of copper. From the study of microstructures by optical metallography and TEM, it has been found that a significant improvement of properties can be attained through a proper selection of TMCP schedule. Precipitation of copper and alloy carbides and dislocation pinning by these precipitates appear to be the principal strengthening mechanisms. Using a lower finish rolling temperature in the TMCP schedule, the precipitation of copper is increased and hence the aging response of the steel becomes poorer. Furthermore, the addition of boron to copper bearing high strength low alloy steels delays the precipitation of copper during post TMCP aging. A higher aging temperature of 600uC of the thermomechanically processed alloys improves the subambient impact strength.

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Among the various surface modification processes, the hot-dip aluminizing process has increasingly evoked considerable attention. This method has proved to be commercially cost-effective and technically better than galvanizing. In contrast to hot-dip aluminized steel components, galvanized components cannot be used in service conditions at elevated temperatures. During the last few years, intensive research by researchers has yielded new insights into metallurgical aspects of aluminized coating in as-dipped and annealed condition. The present review gives a bird’s eye view of the hot-dip aluminizing process, from the early years of its inception to the current research on aspects of the aluminized coating. The progress of research on thermodynamic studies, phase equilibria, phase identification, and their crystallographic features have been traced in this attempt. This review is not restricted to briefing the research performed so far but also points out several issues of discrepancies among the results of the published literature. Special emphasis has been given to the phase development in the coating during annealing and the increasing horizon of application of hot-dip aluminizing to alloy steels in hot stamped conditions. Reference has also been made to state-of-the-art topics embracing the current research on computer simulation software and sophisticated experimental techniques. However, lower surface hardness and economy restrict the wide application of the hot-dipping process.

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