Microstructural and Nanostructural FE-SEM, TEM, and STEM Investigations of High Strength Boron-Alloyed Steel Used in the Automotive Sector

Abstract

Abstract More and more steel grades with martensitic microstructure are used for highly stressed structural components in the automobile branch. They are used in the field of light weight construction and for crash safety. Principally, press-hardened boron-alloyed steels with low carbon content are used here. In this study, the fine microstructure is investigated by means of FE-SEM and TEM microscopy. Possibilities but also limits of the FE-SEM investigation methodology are clearly pointed out and demonstrated presenting concrete examples. In addition to that, further microstructural investigations are performed using a modern scanning transmission electron microscope (STEM). The device allowed for switching from the TEM mode to the SEM mode and thus enabled an investigation of one and the same microstructural section in SEM and TEM conditions; first experiences are presented.