The thermal deformation behavior of BH08G welded steel- 0.08C

1.59Mn

0. 34Mo

0.1215 with strain rate ε 0.1~10.0 s

-1

at 950 ~ 1 050℃ has been studied by Gleeble-1500 thermal simulation machine. It is obtained by regression calculation of austenite recrystallization dynamics that relation between Zener-Hollomon parameter Z and peak stress δ

m

is Z = 3. 829 x 10

12

exp (0.046 46δ

m

)

and relation of lnZ with peak stress δ

m

dynamic recrystallization critical strain ε

m

peak strain ε

m

and dynamic recrystallization finishing strain ε

s

is respectively δ

m

= 21. 338 I

nZ - 516.49

ε

c ≈

0. 83ε

m

= 0.032 6 InZ - 0.732

and ε

s

= 0.052 2 InZ -0.980 1. The dynamic recrystallization state diagram of BH08G steel shows that with rough rolling at 980 ~ 105 0℃ and finishing rolling at 930 ~ 980℃ it is available to fine deformed grain and improve mechanical properties of material.