By directional solidification experiment for a net-shape blade

gating system and directional solidification parameters

sucha s shell preheating temperature

pouring temperature and withdrawal velocity

were optimized.The results show that

in the design of gating system

the blade distribution mode and seeding position are directily relavant with the grain growth and the distribution of temperature field.It is suitable for connecting the seeding with the tenon to avoid distorting deformation of the blade and reduce the metallurgical defects（such as loose

cracks）in the blade.The orthogonal testing reveal that it exhibits negative effects on the grain growth and the solidified surface temperature gradient with a lower shell preheating and pouring temperature or a higher withdrawal velocity.The optimized directional solidification parameters were presented as follows:shell preheating at 1 510

1

520℃

pouring at 1 510

1

520℃and the withdrawal velocity of 5.0mm/min

where the blade with stable thin straight columnar crystal and absence of the surface oblique or broken grain.