Abstract: Plasma nitriding tests of different time and temperatures were carried out on the solid solution treated T250 steel. Microstructure, microhardness, phase and depth of the nitrided layer were measured by means of metallographic analysis, hardness test and XRD. The results show that after ion nitriding, the surface hardness is capable of reaching above 900 HV0.3, and the substrate hardness about 500 HV0.3. The boundary between the diffusion layer of the infiltration layer and the matrix is obvious. The nitriding temperature is similar to the aging temperature of the T250 steel, and the aging strengthening of the steel can be achieved during the nitriding process.

Key words: T250 steel, plasma nitriding, microstructure, microhardness