With using Gleeble-3500 thermal simulator the single pass hot compression deformation and structure evolution of 20 mm hot-rolled plate of 700 MPa pipeline steel (/%: 0.07C

0.90Si

0.60Mn

0.008P

0.002S

0.30Ni

0.10Cr

0.12Mo

0.06V

0.03Nb

0.28Cu

0.04Alt

0.0060N) with strain rate

0.01~1s

-1

at 850~1250°C have been studied to get single pass real stress-strain curves

hot compression dynamic recrystallization diagram and relation between dynamic recrystallization initial time and deformation temperature (RTT) curves. Research results show that deformation temperature and strain rate make certain of initial recrystallization

the 700 MPa pipe line steel easily occurs dynamic recrystallization with strain rate

0.01~1s

-1

at 1100~1250

°C

.the recrystallization mechanism is hot compression causing the original grain crushing and the new grain boundary migrating to prompt formation of new crystal nucleus.