Reverse austenite transformation behavior in a tempered martensite low-alloy steel studied using in situ neutron diffraction

The microstructure evolution during reverse transformation of a Cr-Ni-Mo steel consisting of tempered lath martensite and Cr carbide was examined using in situ neutron diffraction at high temperatures. The microstructural change from a reversed coarse-grained structure to a fine-grained polygonal structure by further annealing was monitored through a decrease in the diffraction intensity caused by primary extinction and the full width at half maximum. This result is different from that for a bainite steel, showing good coincidence with the observations using electron back scatter diffraction. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.