The cold rolling of seamless steel pipe changes martensite to seamless steel pipe before the rolled piece enters the fine extruder. Rough rolling is still carried out under the condition of full martensite. Then, according to the ultra rapid refrigeration system between the fine extruder and the rough extruder, the temperature of hot rolled strip is reduced below the change point before entering the first fine extruder.
The nitriding treatment method of seamless steel pipe is mainly to use the nitriding furnace, put the seamless steel pipe into the feeding frame, and then lift the product workpiece by the driver and put it at the bottom of the furnace for heating. In addition, the nitriding furnace with the design scheme of furnace door lifting load can be made, and the workpiece of wall hanging product can be heated vertically according to the special tools for lifting and wall hanging. The furnace shell of nitriding furnace is generally driven by reducer motor and electric full-automatic elevator. After the furnace cover is closed, another anchor bolt shall be clamped to ensure the tightness of the vacuum pump of the nitriding furnace. Vacuum packaging first, and then N2 is introduced to carry out nitriding heat treatment process.
Nitriding treatment of seamless steel pipe refers to an organic chemical heat treatment method that makes certain substances make the surface of the workpiece of the organic chemical heat treatment process at a certain temperature. Nitriding furnace application nitriding furnace is used to carry out steam nitriding heat treatment process in various steel mechanical parts, car curved glaze, transmission gear, motorcycle brake pad, die shell, etc. In the field of non-ferrous plate, it can be used for bright air-free oxidation quenching of copper materials such as air-conditioning copper pipe, copper coin, copper core wire and copper rod in maintenance atmosphere. Or no air oxidation quenching heat treatment method for vacuum pump N2 maintenance of thick wall seamless steel pipe, stub shaft and various metal parts.
Obviously, because the slab heating temperature of cold rolling in seamless steel pipe zone is lower than that of basic cold rolling, the heating energy consumption can be greatly reduced, and the production of heat treatment furnace can also be improved. Low heating temperature can also reduce the temperature rise of hot-rolled strip, and then reduce the fatigue cracking and fracture of hot-rolled strip caused by internal stress, and reduce the wear of hot-rolled strip; Ultra low temperature cold rolling can also reduce the secondary zinc dust, improve the process performance of hot-rolled products, and improve the operation speed of pickling and passivation line. Life practice has proved that replacing the traditional cold-rolled quenched hot-rolled strip with the thin hot-rolled strip produced by the hot rolling Institute in the seamless steel pipe zone can greatly reduce the product cost.
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