Stainless steel composite steel pipe and manufacturing method thereof

Abstract

The invention discloses a stainless steel composite steel tube and a manufacturing method thereof. The method overcomes the technical prejudices in the prior manufacture of brazing stainless steel composite steel tube, adopts a brass foil with lower price as a brazing material, and avoids the problems of environmental pollution, high cost, large energy consumption and the like in the prior art which uses a nickel-based brazing material coated layer; and a method for performing diffusion brazing by air-cooling a composite tube blank from bottom to top according to a temperature reducing gradient of between 100 and 200 DEG C per minute so as to solidify a brazing solder in sequence from bottom to top not only sufficiently fills the brazing material in the inner and outer tube gaps but also forms diffusion with a distance of a few microns with inner and outer layer materials, wherein an inner layer stainless steel tube and an outer layer carbon steel tube form good metallurgical bonding through a diffusion brazing layer; and simultaneously, the heating temperature, the soaking time and the cooling speed can make carbon steel in a normalized condition to obtain fine textures, and the strength matches well with the plasticity and the stainless steel which is in a solution state and has optimal corrosion resistance at the same time.

Description

Technical field: [0001] The invention relates to an industrial and civil bimetallic composite pipe and its manufacturing method, especially a stainless steel composite steel pipe with good bonding quality, simple process, low cost, good structure and performance of stainless steel layer and carbon steel layer and Manufacturing method. Background technique: [0002] The stainless steel clad steel pipe covered with stainless steel inside the carbon steel pipe has both the excellent corrosion resistance of stainless steel and the high strength of carbon steel. Advantages such as saving resources. The existing stainless steel clad steel pipes can be divided into two types according to the bonding conditions: mechanical bonding and metallurgical bonding. Mechanically bonded stainless steel clad steel pipe, in the process of bending, torsion, etc., or when the temperature, pressure, and load change, the phenomenon of inner pipe instability and bulging will occur, which will easi...

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Problems solved by technology

In this method, nickel-based solder is used, which not only has high cost of raw materials, but also increases the energy consumption due to the high brazing temperature, which further increases the manufacturing cost of the product, resulting in a coarse structure of the base pipe and a decline in performance; the solder is applied by coating. On the outer surface of the liner, there will inevitably be environmental pollution problems; after induction heating, water is sprayed for rapid cooling, although the corrosion resistance of stainless steel is guaranteed, but the plasticity and toughness of the base pipe are greatly damaged

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