Considering of its structure

casting process of control rod was designed and simulated with the help of the View Cast software.The results reveal that shrinkage cavity and porosity can be easily generated in hot spots.In order to eliminate the defects

appropriate chilling blocks were designed and set at the hot spots.Simultaneously

insulating riser was used

and size and number of the riser were also designed.The optimized result shows that large defects can be eliminated effectively

which not only meet requirement of the casting

but also increase the production rate.And then

the castings were normalized at 900

920 ℃firstly

and then tempered at 580

6

00 ℃.So hardness and tensile strength were measured.The results show that the tensile strength and hardness of the samples reach 815 MPa and285 HBW

respectively

meeting the pnduction requirement.