Stability of the structure and phase composition of Kh15N25V4T steel (ÉP164)

1. Steel Kh15N25V4T (EP164) has a structure with a fairly high stability at working temperatures of 550–700°C. 2. The basic hardening phase in this steel is the intermetallic compound βNi3Ti with a fec lattice. 3. Prolonged aging at temperatures up to 750°C has almost no effect on the lattice constant of the βNi3Ti phase; also, the high dispersity of the phase is retained. 4. Along with the β phase, the intermetallic compound Fe2W also occurs. It is formed after a very long incubation period and its dispersity is several orders lower than that of the primary hardening phase (βNi3Ti).