304L/SA210 hot-rolled bimetallic tube blank production method

Abstract

The invention discloses a production method of 304L / SA210 bimetallic thin-wall tube blank centrifugal casting, the bimetallic tube blank can be used for hot-rolled raw material tube blank. During centrifugal casting, the inner and outer metal liquid is respectively poured from two ends of the pipe die; the outer layer 304L metal liquid is mixed and poured by adopting a low melting point protectiveslag; before and during pouring of inner and outer metal liquids are both protected by the inert gas fed by the nozzle; the pouring time of the outer layer 304L metal liquid is no more than 5 seconds, and the pouring time of the inner layer SA210 metal liquid is no more than 8 seconds. In order to prevent excessively fast cooling, the steel ladle used for pouring the outer layer 304L metal liquidis subjected to strict baking and covering heat preservation. According to the 304L / SA210 bimetallic tube blank produced by the technical scheme, the control of the inner layer is good, the content of each component of the SA210 is ensured, and meanwhile, the inner and outer layer interface is clean and free of slag, so that the metallurgical bonding is generated, and the requirement of hot-rolled deformation can be met.

Description

technical field [0001] The invention is applied in the field of centrifugal casting, and provides a production method of a 304L / SA210 bimetallic hot-rolled tube billet used for hot-rolling and producing bimetallic seamless steel pipes. Background technique [0002] 304L / SA210 bimetallic seamless steel pipe is a boiler tube used for black liquor boilers. The outer layer is 304L, which is mainly used to prevent black liquor from corroding. The inner layer SA210 is a commonly used boiler tube. Good, but its thermal conductivity is small, which is not conducive to improving the heat transfer efficiency of boiler tubes, so SA210 is used for the inner layer. [0003] The current specification of the bimetallic pipe is Φ63.5×6.53mm, and the thickness of the outer layer is 1.65mm. It is produced by extrusion and cold rolling. The production method of the extruded tube blank is disclosed by CN10530897B, which is manufactured by centrifugal casting process. In order to ensure the co...

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Problems solved by technology

[0002] 304L / SA210 bimetallic seamless steel pipe is a boiler tube used for black liquor boilers. The outer layer is 304L, which is mainly used to prevent black liquor from corroding. The inner layer SA210 is a commonly used boiler tube. Good, but its thermal conductivity is small, which is not conducive to improving the heat transfer efficiency of the boiler tube, so the inner layer uses SA210

For 304L / SA210 bimetallic seamless steel pipe, the transition layer has an adverse effect on the final heat treatment and performance of the finished pipe, and the yield of the finished pipe is greatly reduced due to the existence of hard and brittle phases.

Later, the method of mechanical inserting disclosed in CN104266003B was adopted to produce extruded bimetal tube blanks to eliminate the transition layer. However, due to the weak bonding force of the inner and outer layers, the yield of cold-rolled finished tubes was also very low, resulting in Φ63.5× 6.53 304L / SA210 bimetallic pipe cannot be industrialized

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