Effect of different solution heattreatments on hot ductility of superalloysPart 2 – Allvac 718Plus

Abstract

The hot ductility of Allvac 718Plus for different solution heat treatments (954°C–15 h, 954°C–1 h, 982°C–1 h and 1050°C–3 h+954°C–1 h) has been investigated using Gleeble testing. Substantial variations in the microstructure among the heat treatments affected the Gleeble test hot ductility only to a very limited extent. Constitutional liquation of the NbC phase was found to be the main cause for the poor ductility at high testing temperatures in the on-heating cycle as well as at the lower temperatures on-cooling. Grain boundary δ phase was seen to assist the constitutional liquation of the NbC phase. Based on established evaluation criteria for Gleeble ductility testing, a ranked indicator for weldability is suggested.

Keywords:

• Allvac 718Plus
• Hot ductility
• Gleeble testing
• Weldability

At the Department of Mechanical and Industrial Engineering, University of Manitoba, we sincerely acknowledge Dr O. A. Ojo for all fruitful comments and advice and Dr K. Vishwakarma and Mr M. Boskwick for all help with the Gleeble testing. C. Knee at the Department of Inorganic Chemistry, Göteborg University, is also acknowledged for performing the DSC measurements.