1.8519 | 31CrMoV9 +QT, plasma-nitrided

31CrMoV9 is a typical nitrided steel and used, for example, for valve stems, worms, crankshafts and other stressed wear parts. The matrix is quenched and tempered. The darker etching of the diffusion zone is due to the fact that fine chromium nitrides are precipitated during nitriding and therefore the matrix is depleted in chromium. In addition, nitrides have precipitated at the grain boundaries in the diffusion zone. In the compound layer, the typical pore fringe can be seen near the surface.