The production process of Φ 14 mm products of steel HRB400 (/% : 0. 21 ~0. 25C

0. 35 ~0. 60Si

1.30 - 1.55Mn

0.045P

0.045S) is 100 t BOF-argon blowing-150 mm x 150 mm billet casting-rolling. In order to resolve the cold-bending cracking phenomenon by increasing yield strength of steel HRB400 besides higher C and Mn content in steel

the commercial pilot production by adding titanium nitride for Ti microalloying and optimizing control rolling-cooling process is carried out. Results show that with decreasing Mn and Si content (/% ) in steel respectively by 0. 35 and 0. 1

and adding 0. 007% Ti in steel (test No2)

or controlling steel reinforced bar going to cold bed temperature at 670 ~ 690 °C

(test No2 )

the yield strength of finished reinforced bar is up to 460 MPa the test aim value ； as using Ti microalloying and optimizing cooling process (/% : 0. 22C

0. 34Si

1. OOMn

0. 007Ti and going to cold bed temperature at 670 ~ 710 °C

test No3) the average yield strength R

el

of test steel is up to 485 MPa

while as using original process (/% : 0. 22C

0. 43Si

1. 37Mn and going to cold bed temperature at 690 ~ 730 X.) the average yield strength R

el

is only 435 MPa.