Hot-rolled seamless steel pipes from pipes to products usually need two heating times, in which porous pipes are heated before and after heating and rolled with a given pre-heating diameter; when pipes need intermediate annealing to eliminate residual stress, cold-rolled (drawn) steel pipes are produced; for some special requirements, in order to improve the mechanical properties, structure and technological properties of steel pipes, hot spots are also carried out. Li. The heating defects of ordinary tubes (tubes) are uneven, oxidized, decarbonized, heated cracks, overheated and overheated.


The purpose of pre-heating perforated tubes is to improve ductility, reduce the deformation resistance of steel, and provide good microstructure by rolling. There are annular furnace, heating furnace, inclined bottom furnace and car bottom furnace. Due to the insufficient diameter of pipeline before reheating, the purpose is to increase the temperature of pipeline, insufficient uniformity, improve ductility of steel, control its microstructure, create favorable conditions for sizing of main pipe and ensure the mechanical properties of steel. Ordinary heating furnace trampling furnace, continuous furnace heating furnace, furnace inclined furnace, induction heating furnace. Cold rolling (drawing) reheating and hardening is mainly to eliminate and reduce deformation resistance. General annealing furnace is mainly used for heating furnace, car bottom furnace and continuous roller bottom furnace. In the production of seamless steel pipe, annular furnace and reheating furnace are the most widely used at present; induction furnace is also being developed; inclined furnace heating furnace is often eliminated because of its low quality and high labor intensity. Continuous roller hearth furnace is mainly used for heat treatment of cold rolled (drawn) steel; car hearth furnace is suitable for heating and holding thick-walled alloy steel pipe with small batch and long heat treatment time; and protective gas continuous roller hearth furnace is mainly used for steel surface requiring heat treatment and cold rolled finished steel, and no oxidation (pull) annealing occurs during pickling process.