Large Diameter Seamless Steel Thermoforming Manufacturing Process

Thermoforming manufacturing processes include large-caliber seamless hot rolling and hot extrusion in two ways, the former mainly for the production of composite pipe joints, the latter using seamless composite pipe production.


Rolling is the traditional method of preparing large diameter seamless steel pipe. Hot rolled composites are substantially below pressure welds, and if the deformation is large enough, the pressure exerted by the metal rolls can damage the oxide film surface, contact the surface atoms, and weld the two surfaces together. The advantages and disadvantages of scrolling are as follows:
Advantages: high productivity, good quality, low cost, can save a lot of loss of metal materials, it is a very broad application of composite materials technology. Rolled composite board composite board, a total of 90%, and is commonly used in processing the wall thickness of 32mm.
Disadvantages: one-time investment, and many material combinations can not be achieved by rolling compound. Currently the most widely used is the rolling process with carbon steel, stainless steel pipe fittings.


Hot extrusion is generally carried out bimetallic tube, known as coextrusion (coextrude). Composite extrusion is currently the best method to produce stainless steel and high-nickel alloy seamless tubes. Three methods are used to prepare composite tubes by extrusion forging billet perforation and hot extrusion, direct centrifugal rotary casting, coupled with corrosion-resistant Powder particles. Two metal raw materials, powders for internal and external applications, called "NuVal" technology, allow the development of new alloys, but the cost of preparing them is too high. Coextrusion shortcomings:
① Advantages: Metallurgical interface; the pressure involved in the extrusion process is completely pressure, it is particularly suitable for hot workability, high alloy low plasticity metal processing.
Disadvantages: Due to the combination of elements in the extrusion process in a very short period of time to spread, usually due to the existence of the oxide film is affected, is currently limited to composite extruded composite carbon steel, stainless steel and high nickel alloys. It should be noted that hot extrusion with small deformation resistance allows various degrees of deformation, resulting in higher surface roughness and hence rolling to hot extrusion (or drawing) to produce a composite pipe.