Klimin V. Formation of tribotechnical properties of steel details by combined mechano-chemico-thermal treatment

Dissertation is devoted to the decision of an actual problem of increasing of tribotechnical properties and restoration of working capacity of details of cars and gears made of constructional steels by a combined mechanical-chemical-thermal treatment (MCTT) by an intensification of shaping of wear-resistant surface layers. For the task in view decision complex MCTT constructional steels with application of a method of a volume hot plastic deformation (VHPD) for the purpose of shaping of wear-resistant stratums of the set structurally-phase composition the mode has been developed for their heightening tribotechnical properties. It is fixed that subcritical (to 3 %) hot plastic deformation ensures an intensification of processes of saturation of constructional steels in a nitrogenous gas environment and leads to considerable (in 1,5 times) to depth increase diffusion a layer and to increasing of its microhardness (on 10-20 %). Thus except increase in depth of a layer with a heightened microhardness in VHPD - modified samples there is a smooth transition of the nitrated layer to a base metal with gradual lowering of a microhardness to corresponding values. It is fixed also that there is such a density of nitrogen (within 6,5…7,5 %) at which hardness of the hardened layer comes nearer to hardness of a gama'-phase, with simultaneous preservation of toughness epsylon-phases, creating, thereby, optimum structural premises for heightening of abrasion resistance of details