High creep resistant refractory stainless steels (super-refractories)

The present invention is encompassed within the ferrous metals processing industry. Particularly, it relates to a new family of refractory stainless steels, particularly ferrous refractory steels, which present advantageous values of creep resistance and crack growth rate, when compared with standard refractory stainless steels, such as 1.4848 refractory steel. The refractory steels according to the present invention have modified chemical composition ranges of main chemical elements that appear in these standard steels (C, Si, Mn, Cr and Ni), incorporate new combined chemical elements such as Mo, Nb and W, and preferably are submitted to an ageing heat treatment for optimum precipitation. These features allow achieving a combined effect that renders significant changes in high temperature properties of these refractory steels. 

Refractory steels comprising Iron, Nickel, Chrome, Silicon, Manganese, Carbon, Molybdenum, and optionally Tungsten and Niobium; in certain proportions, having improbed creep resistance and crack growth rate, and a process of preparation thereof. The steels may be used to manufacture pieces of industrial equipment, such as radiation tubes, especially for heat treatment furnaces; buckets, especially to cantain parts in heat treatment furnaces used in the steels and aluminium flat product; beams; rolls for parts transport in hot stamping sector; trays and rails in the investment casting and ceramic sector; and entrance and outside segments in the mining and cement roasting furnaces.