On the Precipitation Sequence in a 10%Cr Steel under Tempering

Abstract

Precipitation sequence under tempering in a 10%Cr steel has been considered in details. Two different precipitation processes have been identified, concurrently. First, at 350°C, a dispersion of M₂C phase with orthorhombic lattice appears. At 525°C, the M₂C phase is displaced by the formation of M₂₃C₆ carbide. However, this process remains uncompleted. Dissolution of M₂C phase occurs completely due to the formation and growth of more stable M₆C phase as a result of tempering in the range of 650 to 770°C. Second, Nb-rich and V-rich M(C,N) carbonitrides precipitate in the temperature interval of 500–770°C. These dispersoids play a role of heterogeneous nucleation sites for precipitations of M₂₃C₆ and M₆C carbides.