Large-diameter steel pipe continuous casting and rolling production method, composite steel pipe continuous casting and rolling production method and composite steel plate continuous casting and rolling production method

Abstract

The invention discloses a large-diameter steel pipe continuous casting and rolling production method, a composite steel pipe continuous casting and rolling production method and a composite steel plate continuous casting and rolling production method. According to the large-diameter steel pipe continuous casting and rolling production method, the composite steel pipe continuous casting and rolling production method and the composite steel plate continuous casting and rolling production method, a ceramic pipe die is used, the pipe die temperature can be controlled, the controllable permeation thickness of two layers of metal can be achieved, the better interface fusion required by the composite technology is achieved, and the interface bonding force is guaranteed to the maximum degree; pouring of three layers and four layers of metal liquid is easily achieved through controlled cooling, the large-diameter steel pipe continuous casting and rolling production method, the composite steel pipe continuous casting and rolling production method and the composite steel plate continuous casting and rolling production method are particularly suitable for and important for compounding of two kinds of alloys not suitable for mixed melting, the limitation from alloy components is avoided, and real continuous casting and rolling are achieved; and the hot rolling diameter size is not limited, the wall thickness is not limited, and large-diameter steel pipes with the diameter being 1 m or more can be directly produced.

Description

technical field [0001] The invention relates to a continuous casting and rolling production method of a large-diameter steel pipe, a continuous casting and rolling production method of a composite steel pipe, and a continuous casting and rolling production method of a composite steel plate. Background technique [0002] Seamless steel pipes are widely used as pipes for conveying fluids, such as conveying oil, natural gas, gas, water and certain solid materials. At present, the production process of seamless steel pipes mainly includes water-cooled type and thermal mold method, but these two methods have many disadvantages, for example: (1) centrifugal casting has the disadvantage of too fast cooling speed, especially water-cooled type, metal The liquid has not been completely poured, and the temperature of the first poured end may have dropped below 700°C. (2) The outer mold of the hot mold method is mainly a steel pipe mold. The outside of the steel pipe mold needs to be c...

AI Technical Summary

Problems solved by technology

At present, the production process of seamless steel pipes mainly includes water-cooled type and thermal mold method, but these two methods have many disadvantages, for example: (1) centrifugal casting has the disadvantage of too fast cooling speed, especially water-cooled type, metal The liquid has not been completely poured, and the temperature of the first poured end may have dropped below 700°C

(2) The outer mold of the hot mold method is mainly a steel pipe mold. The outside of the steel pipe mold needs to be cooled with water, and it is difficult to ensure the drawing temperature, which makes the rolling process difficult. Moreover, the molten steel inside the steel pipe mold also faces the problem of too fast cooling , there will be a cold skin phenomenon, the produced tube blanks generally have a large wall thickness, a large temperature difference between the inner and outer surfaces, and a large difference in the yield strength of the inner and outer surfaces, which leads to difficulties in continuous casting and rolling

(3) Both the water-cooled type and the hot mold method use steel pipe molds. The steel pipe mold itself will melt at high temperatures, so it is impossible to achieve secondary remelting between the metal layers by heating, especially the first metal layer in production. When it is thin, the cooling rate is too fast, which will cause the interface to fail to achieve metallurgical fusion. That is to say, it is very complicated to realize the production of composite base metal pipes, let alone the realization of continuous casting and rolling.

Even if the first layer of pouring liquid is thick, it is often impossible to roll due to the appearance of cold skin

(6) Water-cooled type and thermal mold method, because the cooling rate is too fast, the thickness of the permeable layer cannot be controlled, and it is generally completed only by solid-state atomic diffusion at high temperature, and the binding force is still not fully exerted

[0003] Due to the limitations of the above conditions, water-cooled and hot-rolled rolling tubes are not available, and the diameter and wall thickness are limited.

Therefore, at present, large-diameter thin-walled steel pipes are generally welded by pipeline steel plates, and pipeline steel plate welding has the following defects: (1) The structure of the base metal adjacent to the weld changes, which affects the mechanical properties; (2) The chemical corrosion resistance of the pipes (3) Welding defects are easy to form at the pipe weld; (4) The production chain is lengthened, which increases the production cost; (5) There are too many additional processes such as flaw detection and heat treatment, which increases the difficulty of construction

[0005] At present, there are mainly several methods for producing composite pipes, such as cold composite method, explosive composite method, centrifugal casting method, brazing method, etc., but these methods have many disadvantages in practical applications, for example: (1) The cold composite method produced Composite pipe, there is no bonding force between adjacent pipe layer interfaces, and the cold composite method has strict requirements on the wall thickness of the matrix, and the matrix pipe requires sufficient rigidity to prevent deformation, otherwise the inner and outer cold composite layers will easily fall off, resulting in cold The composite pipe can only be used for decorative occasions. Although the outer layer of the composite pipe can also play an anti-corrosion effect after being fully sealed, there are strict restrictions on its force load requirements; (2) The explosive composite method requires that the inner layer of the composite pipe is very thin, and the outer layer The layer is thicker, the inner layer must have better plasticity and ductility, and the blasting composite method will cause damage to the matrix metal structure, resulting in a decline in the overall comprehensive performance of the composite pipe, so the scope of application is very narrow

(3) The brazing method uses the thermochemical reaction of several metals and metal compounds to form a new compound as a bonding layer, but the existence of slag affects the interface bonding and easily causes embrittlement

(4) The centrifugal casting method is currently in the stage of small batch production in the laboratory, and the means of producing tube blanks are limited to water-cooled and hot mold methods, which cannot realize continuous casting and rolling, and the composite billet must have strict air cooling and reheating requirements. The finished product rate is low, and it faces the problem of weak interfacial composite effect and weak bonding force

Especially in the past, the composite method was only limited to single-layer composite, and the cost of multi-layer composite was high, mainly because the cost of the composite process was too high, even higher than the price of pure stainless steel plate, thus losing the value of multi-layer composite

[0006] The production methods of clad steel plate mainly include hot rolling method and brazing method. The hot rolling method is to plan the interface of two slabs with a machine tool, pickle, degrease and decontaminate the interface, then stick the interface closely and combine the four sides of the steel plate with gap welding. After strict vacuum extraction, heating and rolling, flaw detection, edge trimming and other processes, the production cost of this method is very high, and if the welding is not strict enough to cause air leakage, oxides on the interface will make the interface unable to bond, so the yield rate relatively low

During production by brazing method, the brazing material between the two layers of plates spontaneously ignites to generate high temperature, which melts the surface layer of the interface between the two layers of plates, and the molten iron connects the interface through the metal oxide gap, but the formed metal oxide is hard and brittle. Make the binding force low, easy to crack when bent and stressed

[0007] In short, the metal composite pipe or metal composite plate prepared by the traditional production process is not only difficult to apply the composite layer to the substrate tube blank with a thinner tube wall due to the insufficient bonding force between the substrate layer or the tube layer and the composite layer. The length of the composite pipe is limited, and it is easy to be damaged during use, resulting in safety accidents

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