The tested low carbon bainite steel (/%: 0.08C

0.11~0.13Si

1.10~1.12Mn

0.008〜0.009P

0.002S

0.21~0.23Ni

0.020~0.021Ti

0.003〜0.004Nb

0~0.0010B

0.0007~0.0008O

0.0031~0.0033N) is melted by a 50kg vacuum induction furnace

rolled to 45mm plate

quenched at 930℃ and tempered at 610°C. The effect of 0.0010% boron on structure and mechanical properties of 45mm plate of 780MPa low carbon bainite steel has been studied. Results show that boron can remarkably improve the hardenability of tested steel

the structure of quenched tested steel without bearing boron is granular bainite

and the structure of quenched 0.0010% boron tested steel is lath bainite. The boron can obviously improve the mechanical properties of tested low carbon bainite steel

the tensile strength 834MPa and yield strength 771MPa of quenched-tempered bearing 0.0010% boron tested steel is higher than the tensile strength 702MPa and yield strength 591MPa of quenched-tempered without bearing boron tested steel. Adding suitable boron in steel in practical production the low carbon bainite steel can get lath bainite structure.