High temperature deformation behaviour of high carbon cast AIM and ESR Fe 3Al alloys

Abstract

The Fe 3Al alloys with the following compositions, Fe–16.2Al–0.54C and Fe–15.5Al–1.1C were melted under flux cover by air induction melting (ATM). Conventional casting defects like shrinkage pipes and microporosity were observed in AIM ingots. Electroslag remelting (ESR) of AIM ingots has resulted in clean, sound ingots free from casting defects. Isothermal, constant strain rate compressive tests were carried out on a DARTEC computer controlled servo hydraulic testing machine over a range of strain rates, 10 −1 to 10 −3 s −1, and temperatures of 1073–1273 K. The cast ESR high carbon Fe–15.5Al–1.1C alloy exhibited high flow stress as compared to the low carbon Fe–16.2Al–0.54C alloy. This may be attributed to the presence of a high volume fraction of hard Fe 3AlC 0.5 particles in the high carbon alloy. The flow stress levels of ESR cast Fe–15.8Al–1.1C alloys were the same in both longitudinal and transverse directions and lower than those of the cast AIM alloy. This may be due to a fine homogeneous axially oriented columnar grain structure free from defects observed in cast ESR ingot. It would appear from the limited present work that isothermal forging of both AIM and ESR ingots of the high carbon Fe 3Al alloy is possible even at temperatures of 1073 K. Non-isothermal rolling or press forging at a moderate strain rate of 10 −1 s −1 would be at starting temperature of 1273 K.