The optimized design of gating system for large-scale ring castings was completed by optimizing the structure

selecting the appropriate material and solidification shrinkage process parameters in combination with the FDM and FEM numerical simulation.The density of oxidized slagis decreases from（12

1

5）/cm2 to（2

3

）/cm

2

and the average diameter is reduced from 2.6 mm to 0.4 mm after the graded melting and refining process.The average grain size is reduced from 176μm to 68μm

and the average tensile strength and elongation are increased about 8%

1

0% and 60% by selecting composite grain refinement

respeotively.The average tensile strength

yield strength and elongation of ZL114 A alloy reach 360 MPa

310 MPa and 8.2%

respectively

based on the multi-stage solid solution and aging process

While the corresponding values of ZL205 Aare 520MPa

460 MPa and 7.4%

and the fractures are characterized by typical dimple rupture.The internal residual stress is reduced from 140MPa

2

50 MPa to 50 MPa

1

05 MPa

and the machining accuracy of high and radial direction is increased about 180% after the cryogenic treatment.In addition the average tensile strength and elongation are increased by 20 MPa

3

0 MPa and 2%

3

.5%

repectiuely

after the T6 treatment.