The influence of V-alloying on microstructure, phase composition and microhardness of high-nitrogen austenitic steels processed by high-pressure torsion (HPT) was investigated. HPT leads to fragmentation of steel structure and increases steel microhardness by ~1.5 times after one revolution of HPT. The different evolution of microhardness of steels investigated with increasing strain was observed. The V-alloying of steel promotes change of the mechanism of deformation under high-pressure torsion: from slip and twinning in V-free steel to slip and formation of localized deformation microbands and precipitation hardening in V-containing steel.