A commercial gear steel (18CrNiMo7-6) containing a tempered martensite structure was nitrided using a pressurized gas nitriding process under a pressure of 5 atm at 530 Â°C for 5 hours. The mechanical properties and microstructure of the nitrided sample were characterized by Vickers hardness measurements, X-ray diffraction, and backscatter electron imaging in a scanning electron microscope. A micro-hardness gradient was identified over a distance of 500 Î¼m with hardness values of 900 HV at the top surface and 300 HV in the core. This micro-hardness gradient corresponds to a gradient in the microstructure that changes from a nitride compound layer at the top surface (âˆ¼ 20 Î¼m thick) to a diffusion zone with a decreasing nitrogen concentration and precipitate density with distance from the surface, finally reaching the core matrix layer with a recovered martensite structure.
|Journal||I O P Conference Series: Materials Science and Engineering|
|Publication status||Published - 2017|
|Event||38th Risø International Symposium on Materials Science - Technical University of Denmark , Roskilde, Denmark|
Duration: 4 Sep 2017 → 8 Sep 2017
|Conference||38th Risø International Symposium on Materials Science|
|Location||Technical University of Denmark|
|Period||04/09/2017 → 08/09/2017|