Investigation on martensitic steel using a quenching-partitioning-tempering process via electron backscatter diffraction analysis

A new quenching-partitioning-tempering (Q-P-T) process was designed based on the recently developed quenching and partitioning (Q & P) treatment by Speer et al. The orientation relationships (ORs) of martensite (alpha) in Q-P-T steel tempered under different conditions were investigated using a scanning electron microscope with an electron backscatter diffraction unit. The morphology and crystallography of lath martensite within a packet were analyzed. Martensites exhibiting an initial austenite (gamma) grain in the orientation image map of different samples were chosen and their {111}(alpha) pole figures were drawn. The pole figures were fitted according to the ideal Kurdjumov-Sachs (K-S) and Nishiyama-Wasserman (N-W) ORs, which were calculated using Matlab and with a gamma crystal-oriented (001)(gamma)[100]. as the reference frame. The martensite OR in the Q-P-T steel follows both the K-S and N-W ORs; however, the K-S OR is predominant. This characteristic does not change in the samples further tempered at different temperatures.