Optimization of Process Parameters for ESR Waspaloy Superalloy by Numerical Simulation

Area of Science:

• Materials Science
• Metallurgical Engineering
• Computational Fluid Dynamics

Background:

• The electroslag remelting (ESR) process is crucial for producing high-performance superalloys.
• Controlling the solidification microstructure, such as dendrite arm spacing, is vital for alloy properties.
• Understanding the thermal and fluid dynamics within the ESR furnace is essential for process optimization.

Purpose of the Study:

• To investigate the temperature, velocity, and solidification fields during the ESR of large-size Waspaloy superalloy.
• To analyze the impact of key process parameters (melting rate, filling rate, slag layer thickness) on molten pool characteristics and microstructure.
• To determine optimal ESR parameters for industrial-scale production of Waspaloy.

Main Methods:

• A transient numerical simulation method was employed.
• The simulation focused on the temperature field, velocity field, and solidified field.
• Key parameters analyzed include melting rate, filling rate, and slag layer thickness.

Main Results:

• The slag pool exhibits high, uniform temperatures (1690-1830 K), with the highest melt pool temperature at the slag-metal interface (1686 K).
• Two pairs of circulating vortices were identified in the slag pool, driven by buoyancy and electromagnetic forces.
• Molten pool depth and dendrite arm spacing increase with melting rate; slag thickness and filling rate have minimal impact without droplet effects.

Conclusions:

• The melting rate is the most significant parameter influencing molten pool morphology and dendrite arm spacing.
• An optimal melting rate of 5.8 kg/min is recommended for industrial-scale ESR of 580 mm diameter Waspaloy ingots.
• Maintaining specific process parameters ensures desirable molten pool characteristics and uniform dendrite arm spacing for enhanced material quality.