A Simulation Method for Predicting Shrinkage Cavity and Cracking Tendency in Waspaloy Vacuum Induction Melting Ingot

Vacuum induction melting (VIM) is a common process for producing high-quality superalloys; however, large shrinkage cavities and cracking often occur in VIM ingots. To improve the quality and reliability of VIM ingot production, a VIM solidification model was established using finite element method (FEM) software ProCAST. High-temperature tensile experiments of Waspaloy ingots were conducted at temperatures ranging from 1200 °C (zero strength temperature) to room temperature. Based on the result, the cracking criterion is constructed by comparing the thermal stress and alloy strength of the ingot using the first and fourth strength theories, to assess the risk of cracking due to insufficient plasticity or strength. And the safe demolding time without cracking was determined according to the solidification time and cracking criterion. The reliability of this method was verified by analyzing the internal shrinkage cavity results and surface quality of a 3 t Waspaloy industrial VIM ingot, longitudinally sectioned at the hot top. Using this method, the effects of important VIM pouring process parameters on the shrinkage cavity and safe demolding time of alloy ingots were analyzed and compared, and this method can be used to predict VIM production results and optimize the VIM process.