Materials Today: Proceedings | 2019
Effect of Temperature Dropping Conditions during Solution Treatments on Final Microstructures of Cast Nickel Base Superalloy, MGA-1400
Abstract
Abstract This research has an aim to evaluate the effect of temperature dropping conditions during solution treatment of reheat treatment process on final restored microstructure of cast nickel base superalloy, grade MGA-1400, a gas turbine blades materials, which had been degraded under long-term service at high temperatures and pressure. Generally, reheat treatment process to restore the degraded microstructure of the alloy consists of solution treatment of 1100-1125°C for 4 hours and precipitation aging of 845-865°C for 24 hours. However, the temperature dropping could be practically occurred due to the machine error of high temperature vacuum furnace. Therefore, the research had simulated various conditions of temperature dropping during solution treatment at temperature of 1100°C and 1125°C with decreasing temperature to 845°C after a) solutioning for 1 hours b) solutioning for 2 hours and c) solutioning for 3 hours then temperature was increased again to the required 1100°C and 1125°C. Then all various solution treated specimens were performed with precipitation aging at temperature of 845°C and/or 865°C for 24 hours. From all obtained results, it was found that the effect of temperature dropping provided the different in received reheat treated microstructures when considering in term of precipitation gamma prime particle morphology such as shape, size and phase density.