Coarsening behavior of M23C6 and Laves phase precipitates during long-term aging in a 10% Cr steel with low nitrogen and high boron contents

Abstract

The coarsening evolution of M23C6 and Laves phase particles in the 10 % Cr steel with 0.008 % B and 0.003 % N during long-term thermal aging at 650 °C for 40,000 h was examined. Particles located on the prior austenite grain boundaries (PAGBs) were compared with those located on the lath/block boundaries. A 5 times slower coarsening of M23C6 on the lath/block boundaries than on PAGBs was attributed to a smaller interfacial energy. After 10,000 h aging, Laves phase particles tended to disappear on PAGBs, whereas larger particles grew on lath boundaries, resulting in a 2 times higher coarsening rate than on PAGBs.