Numerical Simulation and Industrial Experiment of Vacuum Arc Remelting ϕ690 mm Large-sized GH4738 Superalloy Ingot

To study the vacuum arc remelting process and improve the homogenization and cleanliness level of large-sized superalloy ingot， numerical simulation and industrial experiment were carried out to investigate the evolution of molten pool， solidification characteristics and inclusion distribution in a ϕ690 mm GH4738 superalloy ingot during vacuum arc remelting. The results show that as the melting progresses， the simulated molten pool morphology changes from a "shallow flat" shape to a "shallow U " shape. After melting for 500 minutes， the depth of the molten pool and the width of the mushy zone tend to stabilize， with maximum molten pool depth and mushy zone width being 200.88 mm and 72.38 mm respectively. During stable melting， the cooling rate at the surface and center of the casting ingot is 0.126K / s and 0.009 K/s， respectively， and after the height of the ingot is exceeds 0.4 m， the cooling rate of the casting ingot is basically stable.The trajectories of six particle size inclusions in the molten pool were simulated. Large size inclusions （>20 μm） were subjected to the fluid flow and buoyancy to move helically in the molten pool and were eventually trapped at the ingot sidewalls， while small size inclusions （≤10 μm） entered the molten pool and then moved inward along the bottom of the pool， eventually remaining inside the ingot， which is basically consistent with the detection value of the industrial ingot.