1. The formation of a surface layer with high hardness, wear resistance, and ductility is explained by the structural transformations and plastic deformation occurring at the same time in the contact zone heated to high temperatures in the process of the treatment. Along with hardening due to phase transformation (austenite to martensite), strain hardening also occurs due to the high thermal conductivity of this layer. 2. Surface treatment of metals with a high-speed disk is similar to HTTMT (high-temperature thermomechanical treatment), and thus the hardening of the surface layers during treatment with a high-speed disk is due to the same causes as in HTTMT [3]. 3. Treatment with a high-speed disk has several characteristic features. Itrequires no special heating devices or quenching media. Also, all the operations of HTTMT (heating, deformation, quenching) occur at the same time.