Effect of Nitrogen on the Microstructure of AISI M42 High-Speed Steel

摘要

AISI M42 high speed steel is a kind of high carbon high alloy steel. As the most widely used tool steel, AISI M42 high speed steel continue to be manufactured of cutter due to its high hardness level (62-69 HRC)[1]. With the increasing demand of properties in tool steel, improve the chemical composition of tool steel is of great importance. One of the trends in modifying the tool steels chemical composition consists is adding nitrogen[2]. Nitrogen is known to produce some beneficial effects in steels and be regarded as a significant alloying element in ferrous materials. Increasing the nitrogen content could improve the microstructure and hardness of high speed steel. Because nitrogen promoted solid solution hardening and precipitation strengthening reactions that form the basis of many high-strength grades[3]. It has been pointed out that nitrogen has a greater effect on the secondary hardness than carbon. Besides, the higher carbon content, the more influence of nitrogen on the hardness growth[4]. The nitrogen content up to 0.18% could increase the secondary hardness and heat resistance to 1.5-2 HRC[5].