1. Nitriding in a mixture of 50% NH3+50% natural gas at 570° for 6–8 h ensures formation of a carbonitride layer as thick as 20 μ consisting of e and γ′ phases and a diffusion zone with a thickness ∼0.3 mm. 2. Brief nitriding of steel 40Kh increases the fatigue strength more than twice. 3. A process has been developed for brief gas nitriding of the bracket arms of hydraulic pumps permitting the service life to be doubled and leading to substantial savings.