Patent ID: 6565683
Filing Date: 2003-05-20
Classification: B21H,B21J,C21D,C22F

Abstract:
A method for processing a billet, comprising the following steps:heating the billet to a treatment temperature at which a total content of precipitates exceeds 7%; subjecting the billet to a first stage deformation at a first stage treatment temperature to reduce billet cross-sectional area by about 1.2 to 3.9 times; subsequent stage-by-stage reduction of the treatment temperature down to a temperature of formation of a stable fine-grained microstructure, a ratio between grain sizes of different phases in each stage not exceeding 10; subjecting the billet to deformation at each stage of subsequent temperature reduction so as to reduce billet cross-sectional area by about 1.3 to 2.5 times per stage; and subjecting the billet to annealing after each stage; wherein the strain rate at the first treatment stage ranges from 10âˆ’2 to 10âˆ’3 sâˆ’1, and the strain rate at the following stages is set in accordance with the following relationship &egr;&eegr;=K&phgr;Â·&egr;&eegr;&rgr;Â·Td/T&eegr;&rgr;&phgr;â€ƒwhere &egr;&eegr;â€”strain rate at a next stage; &egr;&eegr;&rgr;â€”strain rate at a preceding stage; Tdâ€”next stage deformation temperature: T&eegr;&rgr;&phgr;â€”temperature of the second phase complete dissolution; and K&phgr;â€”empirical coefficient depending on the chemical and phase composition of the alloy.