Microstructure Evolution of a Novel Super304H Steel Aged at High Temperatures

Abstract

The microstructure evolution of a novel Super304H stainless steel aged at different temperatures was investigated using various analysis methods. The results reveal that the microstructure of the Super304H steel after aging at 973–1623 K consists of the primary γ matrix and a small amount of precipitated phases. Grain size of γ-matrix shows a slow increase when the aging temperature is lower than 1373 K and it increases quickly when the aging temperature is beyond 1423 K. The lattice parameter of γ-matrix varies at different aging temperatures, and this variation corresponds to the phases precipitated or redissolved. The variation of grain size and precipitated phases can affect the performance of the steel when exposing to steam oxidation and be subject to creep at high temperatures.