2.2 Hot-extrusion process 

The hot extrusion process is the world's current primary pipe production process in the stainless steel industry. As technology advances, some types of hot-rolled stainless steel tube units can be produced, but the extrusion unit is the world's major producer of stainless steel seamless pipe unit. Currently, there are 60 sets of extrusion units, except for a few for extrusion, 70% of the units are used for the production of steel Extrusion and rolling (longitudinal rolling, cross rolling) production methods are characterized by the extrusion of metal deformation processes under the stress test. In this best stress state, deformation resistance for the large stainless steel tube inside and outside will have a better surface quality and microstructure. The vertical hydraulic equipment through the piercing process improvement, will provide an extrusion wall thickness deviation of 5% to 7% accuracy. It is easy to manufacture, and replace, but it is meant for the production of small quantities and specifications of the stainless steel tube.

The extrusion unit can also produce a wide range of steel pipes, 1 set of 50MN of the extrusion unit can produce 25-254mm steel pipe, and will produce far more than the other rolling method. The stainless steel pipe extrusion production process can be used directly as raw material, the product quality is excellent, and replacement of varieties is flexible, it can manufacture pipe extrusion products, but it is also able to produce all kinds of profiled stainless steel tubes. Clearly, the production of finished pipe by extrusion and cold working requires waste management for the material. Currently, thermal processing is currently used widely in stainless steel production as it is a more economical method; with the high-speed, automation, extrusion machine with large tonnage, along with glass, lubricants, non-oxidative heating, high strength and toughness of hot dye, and other related technologies, with the production of stainless steel seamless pipe extrusion, in particular the difficult production and deformation of stainless steel, the high alloy steel pipe has been rapidly developed. With a single two-roll piercing, the cold method of providing material shortage management, is generally not used by foreign countries.