Process for making superplastic steel powder and flakes

A process for making a consolidated superplastic steel said process comprising the steps of:

• rapidly solidifying molten steel to form a solidified material in the form of a powder, ribbon, or flake comprising single phase austenitic steel having a grain size of no greater than about 2 .mu.m;
• providing said rapidly solidified material of said single-phase austenitic steel having a grain size of no greater than about 2 .mu.m, in powder or flake form;
• heating said powder or flakes of said single-phase austenitic steel having a grain size of no greater than about 2 .mu.m, at a temperature of 300.degree. C. to 600.degree. C. to thus transform said single-phase austenitic steel powder or flakes into superplastic steel powder or flakes consisting of a mixture of a ferrite phase and one or more metal carbide phases, said ferrite phase having a randomly oriented structure and having a grain size of no greater than about 2 .mu.m in any dimension, said metal carbide phases having a grain size no greater than about 0.5 .mu.m;
• hot pressing said powder or flakes at a temperature of 650.degree. C. to 950.degree. C. at a pressure of about 10 MPa to about 100 MPa for a time sufficient to form a consolidated superplastic steel;
• and
• recovering said consolidated superplastic steel.