METHOD OF HEAT TREATMENT OF METAL PIPES (VERSIONS) Russian patent published in 2024 - IPC C21D9/08 C21D1/74 C21D1/70 

FIELD: various technological processes.

SUBSTANCE: invention relates to methods of heat treatment in air of metal articles with an inner cavity, for example, pipes, profiles and others. Method of heat treatment of a metal pipe includes placing the pipe in a heating furnace, heating at a given temperature and time of heat treatment and cooling in air outside the furnace, wherein hollow insert of quartz, ceramic or porcelain is arranged inside pipe with clearance relative to pipe inner surface and heat treatment is performed to produce oxide protective films without scale formation on pipe inner surface. In a version of the method, a hollow insert of quartz, ceramic or porcelain is placed in the inner cavity of the pipe with a gap relative to the inner surface of the pipe, applying a protective coating composition to the outer surface of the pipe and performing heat treatment to obtain oxide protective films and without formation of scale on the outer and inner surfaces of the pipe, wherein the composition used for the protective coating contains, wt.%: kaolin clay 50-25, quartz sand 25-45, boric acid 5-25, water – not less than 250 ml per 1 kg of the mixture.

EFFECT: simplicity of method implementation and obtaining on surface of treated parts more dense defect-free thin oxide films preventing further oxidation of metals.

2 cl, 2 dwg