Crystal structure and chemical composition of precipitates in an aged SUS316L stainless steel

The microstructure of a SUS316L stainless steel which was treated by solid solution at 1100℃ followed aging at 550℃,600℃ and 650℃ for 10000h,respectively was investigated.The morphology,size and distribution of the precipitate were observed by using transmission electron microscopy(TEM).Electron diffraction was conducted to characterize the crystal structure of the precipitate formed in the stainless steel.The chemical composition of the precipitate was analyzed by means of analysis electron microscopy equipped with an energy dispersive spectrum system(AEM-EDS).The results show that the precipitate of M_(23)C_6 carbide mainly composed of chromium occurs in the SUS316L stainless steel aged at experimental temperatures.Most of the carbide form along the grain boundaries of the stainless steel and a few disperse inside the grains or along the crystal defect like as stacking fault.Both the size and volume of(M_(23)C_6) precipitate increase with increasing aging temperature.