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Manufacturing method of dual-metal seamless steel pipe with outer-layer low-carbon steel and inner-layer bearing steel

A technology of seamless steel pipe and manufacturing method, applied in the direction of manufacturing tools, heat treatment equipment, furnaces, etc., can solve problems such as corrosion, pipe scrapping, uneven corrosion state, etc., and achieve the effects of avoiding environmental pollution, high work efficiency, and smooth surface

Inactive Publication Date: 2012-10-17
XINXING DUCTILE IRON PIPES CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, acid pollutes the environment and is harmful to the human body
The bimetallic hot-rolled seamless steel pipe of outer carbon steel and inner bearing steel is composed of two materials, and the electrode potentials of different materials are different. When the original battery is produced, the surface of the tube will have an uneven corrosion state, the metal with high potential will not be corroded, and the metal with low potential will be corroded quickly, resulting in a large number of pits on the surface of the tube, seriously affecting the surface quality, and even causing the tube to be scrapped, causing huge Economic losses

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Example 1: (1) The material of bimetallic seamless steel pipe is 14MnV / GCr15, that is, the outer layer is 14MnV, and the inner layer is GCr15. mm+ inner wall thickness 2.6mm).

[0024] (2) The tube blank used is a hot-rolled bimetallic seamless steel tube, the specification is outer diameter φ = 159mm, total thickness of the tube wall = 7mm (outer wall thickness 2.8mm + inner wall thickness 4.2mm).

[0025] (3) Tube billet spheroidizing annealing

[0026] Heat the tube billet to 790-810°C, keep it warm for 4-6 hours, and then start cooling at a cooling rate of 30-35°C / h, then cool to 400-500°C with the furnace, and air-cool when it comes out of the furnace to reduce stress, soften the structure and improve plasticity.

[0027] (4) High-pressure sandblasting to remove iron scale

[0028] Add a certain amount of water to the quartz sand, the volume ratio of quartz sand to water is 1.2-2:5, and stir to form a water-sand mixture. The sandblasting pressure of the nozzle he...

Embodiment 2

[0036] Embodiment 2: (1) The material of the bimetallic seamless steel pipe made of low carbon steel on the outer layer and the bearing steel on the inner layer is 10MnV / GCr15, that is, the outer layer is 10MnV and the inner layer is GCr15. Thickness = 4.5m (outer wall thickness 2mm + inner wall thickness 2.5mm).

[0037] (2) The tube blank used is a hot-rolled bimetallic seamless steel tube, the specification of which is the outer diameter φ = 133mm, the total thickness of the tube wall = 5.5mm (outer wall thickness 2.3mm + inner wall thickness 3.2mm).

[0038] (3) Hot head of tube billet

[0039] The head side of the hot-rolled bimetallic seamless steel pipe billet is heated to 800-900°C, the length of the heating section is 270-300 mm, and the length of the head area is 150-200 mm.

[0040] (4) Tube billet spheroidizing annealing

[0041] Heat to 790-810°C, keep it warm for 4-6 hours, then start to cool, the cooling rate is 30-35°C / h, cool down to 400-500°C with the furna...

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Abstract

The invention discloses a manufacturing method of a dual-metal seamless steel pipe with outer-layer low-carbon steel and inner-layer bearing steel, which relates to the technical field of heat treatment of iron-based alloy. The manufacturing method comprises the following steps of: pipe blank spheroidizing annealing; straightening; oxide layer removing by high-pressure sand blasting; cold rolling, and cold drawing; destressing and annealing; oil spot and phosphorus removing by high-pressure sand blasting; finishing; and warehousing. According to the method, scales and oil spots are removed by the sand blasting which is performed by a mixture of water and aluminum oxide sand or quartz sand, so that not only are environment pollution caused by acid liquid and surface defects caused by the nonuniform corrosion of a pipe blank are avoided, but also after the sand blasting treatment, the surface of a pipe is flat, clean and smooth, the pollution is avoided, and the pipe is safe to use. Additionally, as the pipe blank progresses uniformly and spirally on a delivery roller way, the increasing of sand blasting passages caused by intermittent removing of the scales and the oil spots is prevented, and thus the working efficiency is high.

Description

technical field [0001] The invention relates to the technical field of heat treatment of iron-based alloys, in particular to a method for manufacturing a double-metal seamless steel pipe with an outer layer of low-carbon steel and an inner layer of bearing steel. Background technique [0002] Through the centrifugal casting process, a bimetallic tube billet with an outer layer of low-carbon steel and an inner layer of bearing steel is prepared, and then through a hot rolling or hot extrusion process, a finished tube with high performance can be successfully produced. However, the thermal processing process can only produce finished pipes with a wall thickness of more than 5mm. If you want to produce a composite pipe with a smaller wall thickness and higher dimensional accuracy, you generally use hot-rolled seamless steel pipes as blanks, and cold-rolled and cold-drawn methods. conduct. The outer surface and inner wall of the hot-rolled seamless steel pipe are covered with i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21C37/06C21D1/32C21D9/08C21D8/10
Inventor 王黎晖庞于思王锦永宋亚峰申勇高杰
Owner XINXING DUCTILE IRON PIPES CO LTD
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