The production mode of stainless steel seamless tube mainly includes hot extrusion, hot rolling and cold processing technology.
(1) hot extrusion process.
Hot extrusion process is the main production process of stainless steel seamless pipe.
The extrusion process is characterized by three compressive stresses in the deformation process compared with the rolling (longitudinal and slanting) production methods.
In this optimal state, the stainless steel tube with large deformation resistance and thermal plasticity can obtain better internal and external surface quality and metallographic structure.
Due to the improvement of the vertical hydraulic perforating process equipment, the thickness of the wall thickness can be 5% ~ 7%.
The extruder mould is easy to manufacture and replace. It is suitable for producing small batch, multi-specification stainless steel tube, especially for high alloy steel which is difficult to be machined by inclined rolling mill.
(2) hot rolling process.
Widely used at home, stainless steel pipe perforation two-high skew rolling piercer, not only common austenitic stainless steel, including difficult deformation of duplex stainless steel and high temperature alloy were also can batch production on two-high skew rolling piercer.
If choose two-high tapered roller puncher, but the production of steel grade, capillary inner surface defects such as folding, surface defect, especially internal crack less, produce the wall thickness is thinner hair at the same time, through all kinds of mill (vertical mill, skew rolling) can be more thin wall rolling, thereby reducing cold drawing (rolling) time, productivity and yield was improved, and economic benefit increased significantly.
(3) cold processing technology.
50% ~ 80% of stainless steel is manufactured by cold process.
There are basically three kinds of cold processing technology, namely cold drawing process, cold rolling process and cold rolling - cold drawing combined process.
Cold-rolled stainless steel tubes are mostly cold-rolled and cold-drawn joint production process, which is mainly cold-rolled and cold-drawn.
The advantages of cold-rolling and cold-drawing combined production process are: the quality of steel pipes is good, the thickness of cold rolling steel pipe wall is high, the surface quality is better, and the cold drawing ensures the precision of the steel pipe.
The cold machining cycle is short, reducing the process of intermediate degreasing, heat treatment, shrinkage and straightening, saving energy and reducing metal consumption.
Large size waste pipe can be used to produce small diameter steel pipe to simplify the raw material specification.
Cold rolling mill, cold drawing machine forward high - speed, high - precision, long - run, multi - line development.
Modern cold rolling mill can achieve large reduction and reduction.
The wall volume, the rolling deformation of 80% on the cold rolling machine.
Adopt cold rolling and cold drawing to change the specification and control the outer diameter to meet the requirements of different varieties and specifications.