Nanoindentation investigation on the mechanical stability of individual austenite grains in a medium-Mn transformation-induced plasticity steel

The mechanical stability of individual retained austenite grains is studied by nanoindentation combined with electron backscattered diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The average hardness of retained austenite and ferrite is 7.7 and 3.4 GPa, respectively. The large scatter of hardness distribution in retained austenite may be due to the varied stability and boundary structure of different austenite grains. The mechanical stability of retained austenite increases with Mn content.

Bright-field TEM image showing martensitic transformation of a retained austenite grain subjected to nanoindentation (α′: martensite, γ: austenite).Figure optionsDownload high-quality image (170 K)Download as PowerPoint slide