Morphology of Ti-Al Inclusions in Ultrapure Ferritic Stainless Steel

In this paper,the Ti-Al inclusions in ultra-pure ferritic stainless steel were studied.The Ti-Al inclusions in steel were observed by two-dimensional metallographic method and three-dimensional anhydrous electrolysis.Tungsten filament and field emission scanning electron microscope were used to observethe morphology,and its elemental composition was analyzed by an energy spectrometer.The results show that various forms of alumina inclusions are formed in the ultra-pure ferritic stainless steel after Al deoxidation.These deoxidation products will affect the subsequent Ti alloying and form a Ti-Al composite with excessive local titanium content.The equilibrium curve of TiN inclusions and the Ti-Al equilibrium curve in ultrapure ferritic stainless steel were obtained by classical thermodynamic calculations.The calculations showed that the formation of TiN should be in an unfavorable state at the experimental temperature and elemental content,but due to the local enrichment of Ti and N elements,TiN formed during the deoxidation product indicating or solidification.