It is particularly preferable for very rounded particles to be formed, with a mean elongation between 1 and 1.5.With UHC lightweight structural steels according to the invention the procedure for producing a superplastic structure can be as follows:A. Largely complete austenitization, depending on the C, Si, Al and Cr content in particular at 10000 to 1150?? C. This produces a homogeneous distribu