Characteristics of AlN Precipitation and Growth During Solidification of FeCrAl Stainless Steel

In the present work, AlN precipitation and growth were investigated in a FeCrAl stainless steel with high aluminum content (Al wt pct = 4.07). The effect of the cooling rate on the number and size distribution of AlN particles was analyzed with the directional solidification method and the field emission scanning electron microscope. A coupled model of solutes micro-segregation and diffusion-controlled inclusion growth was also established in combination with the interaction between the inclusions and advancing solidifying interface, to characterize the precipitation and growth of AlN during solidification of FeCrAl stainless steel. The results indicate that the AlN particles with the hexagonal wurtzite crystal structure belong to the P6(3)mc space group. AlN precipitates in the mushy zone during solidification. The growth of AlN is controlled by the diffusion of nitrogen. The increased cooling rate could increase the number density of AlN and reduce the size of AlN particles. The coupled model can be used to predict AlN size distribution and solutes distribution in solid and liquid phases during solidification.