Effects of hot deformation and heat treatment on grain refinement for as-cast and spray formed SA508-3 steel

摘要

In order to identify quantitatively the different effects of hot deformation and heat treatment processes on the grain size of as-cast and spray formed SA508-3 steel, two kinds of billets were produced respectively. Samples were machined, forged and heat-treated in sequence under the same conditions for both billets. Then, the corresponding microstructures were observed and analysed for each process. The experimental results demonstrate that both hot deformation and heat treatment are beneficial to refine the grains of the as-cast and spray formed billets. Furthermore, the grains of spray formed samples are much finer and more uniform than that of as-cast ones. It indicates that the spray forming process is more competitive for grain refinement than the conventional casting. However, the existence of voids in the spray formed is detrimental for the mechanical properties, especially the elongation. Therefore, not only the spray forming process but also the hot deformation parameters should be further improved to densify the microstructures and guarantee the complete closure of voids.