MORPHOLOGICAL STABILITY OF GAMMA ALPHA-INTERFACE FORMED BY CARBURIZATION IN FE-C-X ALLOYS/

Effect of alloying elements on the morphological stability of austenit e/ferrite interface formed by carburization of Fe-X alloys at 850-degr ees-C and 800-degrees-C was investigated. Planar interfaces were found when the alloying elements added were from among the following: Ti, V , Nb, Ta, Cr, Mo, W, Co, and Cu. Nonplanar interfaces with Widmanstatt en-like structures and/or an isolated phase were observed when the all oying elements were from the following group: P, Al, Sb, Ni, Mn, Si, a nd Ge. The degree of supersaturation of C in the alpha phase adjacent to the gamma phase front was analyzed using the concept of local equil ibrium. It was confirmed that there was indeed a close correlation bet ween the morphological stability and the degree of C supersaturation, which in itself depended on whether the alloying element added was an alpha or gamma stabilizer and how strongly it bonded with C in the fer rite phase.