Microstructural characteristic of the 24Cr2SiMn super ferritic stainless steel synthesized using local Indonesian materials

Precipitation is a key factor for the mechanical properties of material at high temperature application. It is important to study the formation and stability of precipitates in order to optimize the material properties. In this article, the author presents the preliminary results of the microstructure including precipitates formation in Fe-24Cr-2Si-0.8Mn (wt%) super ferritic stainless steel. Both the X-ray and the HRPD neutron diffraction pattern characterizations showed the first four characteristic reflections intensity with Miller indices corresponding to the (110), (200), (211), (220) diffraction planes that are typical for diffracting plan (hkl) of bcc system. The Scanning Transmission Electron Microscopy (STEM)-High Angle Angular Dark Field (HAADF) images and semi-quantitative Energy-Dispersive X-ray Spectroscopy (EDS) revealed the presence of chromium-carbide and chromium rich precipitates in rod-like shape with the size of about 700 nm in length and 250 nm in width. EDX semi-quantification results showed that the precipitate in the ferritic sample typically consists of 55.04 wt%C, 0.78 wt%Si, 35.42 wt%Cr, 0.68 wt%Mn, and 8.37 wt%Fe. Moreover, Selected Area Electron Diffraction (SAED) analysis revealed (Fe,Cr)7C3 as one of the chromium-carbide formed as precipitates. Finally, HRTEM images showed atomic structure of matrix and precipitates at dendrite boundaries at atomic level.