Optimization of Thermomechanical Parameters to Produce an Ultra-High Strength Compressor Disk

Structural steels with very high strength levels are often referred to as ultrahigh-strength steels (UHSS). The usage of UHSS has been extensively studied in aerospace industries and offshore platforms. In this study, medium carbon low alloy steel (AMS6305) was thermomechanicaly treated to obtain an ultra-high strength bainitic steel for aircraft engine compressor disk. A novel themomechanical treatment was introduced to optimize microstructure and mechanical properties. By replacing the common quench-temper microstructure of compressor disk with bainite microstructure, an ultra-high strength bainitic steel was achieved. Based on the results obtained, the final microstructures following pre-deformation and subsequent heat treatment showed a very good combination of strength and toughness. Furthermore, it has been shown that austempering time and temperature play a major role in achieving ultra-high strength bainitic steels. The optimized strength and toughness was achieved by up quenching treatment. This is due to partitioning of prior austenite grains by tempered martensite plates.