At present, continuous casting is mostly used in the production of stainless steel, and the caster is mainly vertical and arc. Compared to the traditional ingot - rolled billet, the quality of the stainless steel continuous casting billet is better, the yield of the metal is increased by 10%-15%, and the effect is obviously reduced. At present, the main technology of manufacturing stainless steel seamless pipe is hot extrusion. While gradually eliminating hot rolled steel pipe sets, extrusion unit is becoming the main unit of stainless steel seamless pipe production all over the world.
In addition to a small amount of extrusion for extrusion, most of these extruding units are used to make steel pipes, the main varieties are stainless steel seamless pipes. Compared with the rolling process, the extrusion process is characterized by the compression stress of three directions in the process of metal deformation. Under such optimum stress state, stainless steel seamless pipes with high type and high deformation resistance can form satisfactory deformation, internal and external surface quality and microstructure state.
Through the extrusion process to the maximum benefits of stainless steel seamless pipe can be as raw materials directly to continuous casting, stable quality of stainless steel seamless pipe, and the replacement is flexible, can directly produce hot extrusion finished stainless steel seamless pipe, can also be used to produce various kinds of special-shaped stainless steel seamless pipe. However, the drawback of the manufacture of stainless steel seamless pipe by extrusion method is that the rate of production is low.
In order to increase the yield of stainless steel seamless pipe, the production process is optimized. If the high required variety usually uses the pre drilling, the hydraulic piercer expansion and the extrusion process. The requirement of cold processing of raw materials in general pipe according to the actual situation with different production processes, such as small size stainless steel seamless pipe with solid billet directly in the vertical hydraulic punch and extruded pipe; medium size stainless steel seamless pipe with blank is pre drilled holes, vertical hydraulic reaming and extrusion punch into large steel pipe; the specifications with blank pre drilling larger holes, directly into the extrusion pipe. Obviously, it is a cost-effective method to produce finished products and provide raw materials for cold processing by extrusion.
In addition, the cold rolled stainless steel seamless pipe mostly uses cold rolling and cold drawing as the auxiliary production process. The stainless steel seamless pipe of 50%-80% should be made into finished products by cold processing. Therefore, the cold processing equipment will develop greatly. There are three main cold processing technologies, which are cold drawing, cold rolling, cold rolling and cold drawing. The cold rolling and cold drawing process of the stainless steel seamless pipe in foreign countries is mostly cold rolling and cold drawing, which is the main part of cold rolling.
At present, the cold rolling mill can complete the large wall reduction and the large reduction of the stainless steel seamless pipe, and 80% of the deformation can be done directly on the cold pipe mill. The production requirements of different specifications and varieties can be achieved by changing the wall of cold rolling, changing the specification of steel pipe and controlling the outer diameter with cold drawing.
This is the advantage of the quality of the finished production process of stainless steel seamless pipe, and the pipe wall thickness and fine and high surface quality, high precision cold drawn steel pipe diameter, cold processing cycle short, omitting the middle of degreasing, heat treatment, necking, straightening process and pipe material consumption, effective energy saving, but also simplify all kinds of raw materials, so as to expand the scale of production.
Source: China Stainless Steel Seamless Pipes Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)