The effect of single roll soft reduction (0〜14 mm) and reduction position ( 1

#

~ 7

#

) on inacrostructure and central carbon segregation of 240 mm x 240 mm casting bloom of low carbon steel 20CrMnTiH has been tested and studied. Results show that as from roll No. 3 reduction and maximum soft reduction 9 mm

the ratio of the without shrinkage cavity increases by 12.3% and the ratio of center porosity 1.0 rating and center carbon segregation do not improve obviously ；as from roll No. 2 reduction with maximum soft reduction 1 1 mm

the ratios of center porosity 1.0 rating and the without shrinkage cavity decrease

and the ratio of center carbon segregation increases by 14. 2% ； as from roll No. 1 reduc

tion and the maximum soft reduction 14 mm

the ratios of center porosity 1.0 rating and without shrinkage cavity are up to 100%

and the ratio of center carbon segregation is 71.4% . By comprehensive analysis it is obtained that with casting speed 0.85 m/min

mold stirring 300 A and 5 Hz

the central carbon segregation and macrostructure of steel 20CrMnTiH 240 mm x 240 mm casting billet are better by single roll soft reduction 14 mm.