Abstract: An improved method for casting metallic material while toughening the cast piece is described herein. Essentially, the improved method utilizes a part of the thermal energy used for casting to toughen the cast piece by making use of super-plastic phenomena. After metallic material poured into a mould has been solidified, the mould is disintegrated during the period when the temperature of said metallic material is at a raised temperature higher than the temperature of 100.degree.C under a phase transformationpoint. Under the condition where the thus obtained intermediate product is loaded with a low stress of the order of 1/10 - 1/20 of the yielding point stress of said metallic material, super-plastic phenomena are generated by applying temperature cycles passing over said phase transformation point, and thereby said intermediate product is subjected to toughening treatment.

Abstract: A method of working metallic material with roll dies resulting in toughening of the worked material is herein described, which method is characterized in that said metallic material is worked with roll dies while generating super-plastic phenomena by applying a temperature cycle passing over a transformation point to said metallic material.