Tested 0.5 ~0.7Cr steel for bucket blade (/% : 0.22 ~ 0.30C

0.25 ~ 0.45Si

0.95~1.20Mn

0.006 ~ 0.009P

0.008 ~0.010S

0.5 ~0. 7Cr

0.015 ~0. 065Nb

0 ~ 0. 040Ti) is melted by a 50 kg vacuum induction furnace and hot-rolled to 16mm plate with finished rolling temperature 850 ~ 900 °C

air cooling. The effect of Nb-Ti content (0. 015Nb

0. 035Nb-0. OlOTi and 0. 065Nb-0. 040Ti) on structure and mechanical properties of hot-rolled steel for bucket blade has been studied by optical

scanning electron and transmission electron microscope and mechanical properties examination. Results show that the structure of tested steel is ferrite + pearlite ； with increasing Nb-Ti content in steel

the grain in steel plate is fined

the lamellar spacin

g of pearlite decreases and the amount of precipitates of (Nb

Ti) C and ( Nb

Ti) (C

N) and the strength increase； and the mechanical properties of steel plate containing 0. 065Nb-0. 040Ti is yield strength 632 MPa

tensile strength 916 MPa

elongation 17.7%

impact energy K

AV

40 J and HB hardness value 234.