METHOD OF THERMODIFFUSION ZINC COATING FASTENERS FROM BAINITE CLASS STEELS WITH SIMULTANEOUS INCREASE OF COLD RESISTANCE THEREOF Russian patent published in 2017 - IPC C23C10/36 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical-thermal treatment of items, specifically, to technology of thermodiffusion zinc coating of fasteners made from bainite class steels, intended for production of parts and assemblies, operating under conditions of Far North and Siberia, for example, in loaded threaded joints of bridges, bulldozers, excavator for mining operations, offshore drilling rigs, ice ships. Method of thermodiffusion zinc coating fasteners made from bainite class steel, subjected to quenching and subsequent high tempering, includes placing parts in rotary drum of heating furnace with charge, containing zinc powder, alumina and activated carbon, heating to temperature of 450±10 °C and holding at said temperature until extraction and coagulation of tertiary cementite, wherein content of zinc powder is determined from relationship: m=0,36τ²-6τ+30, wherein m is zinc content in % of charge weight, τ is duration of thermodiffusion zinc coating.

EFFECT: higher cold resistance of fastener and creation on its surface of a corrosion- and wear-resistant diffusion zinc coating.

1 cl, 1 dwg, 3 tbl