Features of nitrided layers in martensitic steel obtained by direct laser melting

Analysis of nitrided layers formed on 25-Cr-13-Ni-2 martensitic class steel obtained by the additive manufacturing process of direct laser melting (DLM) is performed. It is shown that in the process of nitriding in a glow discharge at a temperature of 540 °C for 24 hours, the thickness of the diffusion layer for steel obtained by the DLM method is more than 2 times greater than the layer formed in the same nitriding process for steel obtained by rolling with subsequent improvement. The formed layer on the steel obtained by the DLM method is about 140-160 microns, against approximately 70 microns on the steel obtained by rolling. In the layers obtained on steel produced by the DLM hardness also decreases with depth more slowly than hardness in a layer on steel produced by rolling. X-ray phase analysis revealed the strengthening phases in the nitrided layers, which is the same for all studied cases: y' and CrN nitrides. © 2022 Author(s).