The thermal deformation behavior of 420 mm casting slab of 690 MPa high-strength steel for ocean engineering (/% ：0. 12 〜0. 15C

1.05 ~ 1.20Mn

0.5 ~0. 7Cr

1. 0 ~ 2.0Ni

0. 5 ~0. 6Mo

0. 3 ~0. 6Cu

0.015 〜0.035Nb

0. 008 〜0. 020Ti

0. 04 ~0. 07Alt) with 20% deformation and strain rate 0. 05 ~ 5 s

-1

at 1 000 ~ 1 100 ℃ has been tested studied by using Gleeble 3800 thermal simulation machine to get true stress-strain curves

strain-hardening rate-deformation stress curves

thermal deformation constitution equation and dynamic recrystallization thermal activation energy of the steel. Results show that at same test temperature with increasing strain rate the corresponding deformation stress increases ； while with increasing deformation temperature the deformation stress decreases ； and the dynamic recrystalli

zation thermal activation energy of the steel is 499 954. 0 J/mol.