Revealing heterogeneous C partitioning in a medium Mn steel by nanoindentation

The present work employs nano-indentation technique to investigate the C partitioning in a medium Mn steel subjected to quenching and tempering process. It is found that the C partitioning between martensite and austenite is inhomogeneous. Particularly, the large lenticular martensite has negligible C partitioning into the austenitic matrix as it maintains an ultra-high nanohardness comparable to the one without tempering. Strategies to suppress the formation of large martensite are discussed.