Abstract
AISI M2 steel is the one of the most well-known high speed steels (HSSs) [1]. The M steels contain molybdenum as their main alloying element and they have properties (wear resistance, red hardness, toughness), that permit efficient metal removal in 70% of drilling and milling applications [2]. Almost all the energy used during the machining processes to plastically deform the material is converted into heat [3]. Friction on both tool/chip and tool/workpiece interfaces generate heat and negatively influences the tool life and the quality of machined surface [4]. The most common cause of failure of machine parts and tools is the wear of their working surface [5]. Coatings are today being increasingly to improve the tribological performance of the cutting tools to increase tool life [6, 7]. Boron-based coatings are the leaders in improving properties such as wear resistance, heat resistance and hardness [5]. The boriding process is a thermochemical surface treatment, in this process, the boron is diffused into the material surface at the high temperature to form a hard layer composed of iron borides (single phase Fe2B or double phase FeB+Fe2B) at the surface [8]. This study investigates the friction and wear evolution of borided and unborided AISI M2 steel under dry sliding conditions using the pin-on-disc apparatus, to find the most suitable parameters of the thermochemical boriding treatment for application in solid twist drills.