Hüseyin Çimenoğlu

Nitriding is an attractive surface hardening treatment for many steel grades to enhance their surface related mechanical properties such as hardness and wear resistance. Conventionally, it is employed in temperature range of 500–600 °C to form graded surfaces consisting of a compound layer with a nitrogen diffusion zone beneath it. In practice, the thickness of the compound layer is mostly kept in between 5 and 10 µm, while the depth of the nitrogen diffusion zone is more than 10 times of the compound layer thickness. As in the case of impact-extrusion dies manufactured from hot work steels, conventional nitriding may form a compound layer susceptible to cracking and spalling leading early failure. Conventional nitriding, on the other hand, is not favorable for stainless steels as it causes early failure by corrosion attack. In the scope of this presentation, studies conducted at Istanbul Technical University on nitriding of hot work tool and austenitic stainless steels will be introduced. For the hot work tool steel, the target was optimizing nitriding process to enhance the high temperature wear resistance under impact and sliding loading conditions. In the case of austenitic stainless steel, the aim was determining the impact of nitriding at a temperature much lower than that of conventional nitriding, on corrosion, wear and fatigue performances.