Microstructure, macro-, and nano-hardness assessment of AISI 302 steel aged at 1000°C

Abstract

Changes in the microstructure of the AISI 302 steel must be analyzed in order to optimize its mechanical performance. In this paper, we studied the thermal aging behavior of the AISI 302 steel. The aging treatments of the steel were carried out at a fixed temperature of 1000°C and for durations between 0 and 6000 minutes. A metallographic microscope was used to see changes in the AISI 302 steel microstructure. In addition, the steel was mechanically characterized using the nano-indentation technique and macro-hardness tests. At the temperature investigated, the aging time increase caused a microstructure composed of large austenitic grains and a small area of grain boundaries per unit volume. For the mechanical characterization, the nano-indentation responses also showed a decrease in the nano-hardness and plasticity of the austenite as the aging time increased. The steel macro-hardness decreased significantly by incrementing the aging time.