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Manufacturing method for large-diameter austenitic stainless steel thick-wall pipe

A technology of austenitic stainless steel and a manufacturing method, which is applied in the directions of manufacturing tools, metal rolling, metal rolling, etc., can solve the problems of large-diameter thick-walled tubes with coarse grain size, long production cycle, and low yield, etc. The effect of reducing the manufacturing process, improving the yield and improving the uniformity

Active Publication Date: 2017-05-24
CENT IRON & STEEL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a method for manufacturing austenitic stainless steel large-diameter thick-walled pipes, which avoids the defects of low yield, long production cycle, and high cost of adopting the forging solid (hollow) billet+machining method, and Solved the problem of coarse grain size of austenitic stainless steel large-diameter thick-walled tubes produced by purely using Pilger hot rolling mill or purely adopting large-diameter cold rolling mill

Method used

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  • Manufacturing method for large-diameter austenitic stainless steel thick-wall pipe
  • Manufacturing method for large-diameter austenitic stainless steel thick-wall pipe
  • Manufacturing method for large-diameter austenitic stainless steel thick-wall pipe

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Experimental program
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Effect test

Embodiment 1

[0053] Homogenization heat treatment of embodiment 1 hot-rolled tube billet

[0054] figure 1 , figure 2 and image 3 The grain structures of the inner wall, core and outer wall of the hot-rolled billet with furnace number 1# after heat treatment at 1080°C are shown respectively; Figure 4 , Figure 5 and Figure 6 The grain structures of the inner wall, core and outer wall of the hot-rolled billet with heat number 1# after homogenization heat treatment at 1180°C are shown respectively. After the hot-rolled tube blank is heat-treated at 1080°C, the inner and outer walls are completely recrystallized, the recrystallized grain size is small, the recrystallization in the core is not complete, and there is still an incompletely recrystallized as-cast structure; after 1180°C high temperature uniformity After the heat treatment, the inner wall, outer wall and core have completely recrystallized structure, and the grain size is relatively uniform. It can be seen that increasin...

Embodiment 2

[0055] Embodiment 2 Microstructure regulation and annealing heat treatment of cold-rolled tube billet

[0056] Figure 9 , Figure 10 and Figure 11 The grain structure of the core part of the tube wall after the heat treatment of the cold-rolled tube blank with the furnace number 2# after the microstructure control heat treatment at 830°C, 930°C and 1050°C respectively is shown. After heat treatment at 930°C and 1050°C, the cold-rolled tube billet has undergone complete recrystallization. After heat treatment at 1050°C, the recrystallized grain size in the core of the tube wall is large, and its grain size is 3.5. After heat treatment at 930°C, the tube wall The recrystallized grain size in the core is small, and the grain size is 4.5; after heat treatment at 830 ℃, the cold-rolled tube billet is not completely recrystallized, and the grain is coarse, which is 2.0. Figure 8 The relationship between the annealing heat treatment temperature and the grain size of the core of...

Embodiment 3

[0059] Embodiment 3 roll diameter

[0060] Rolled by cold rolls with diameters of 600mm, 800mm and 1000mm The grain size of the core part of the pipe wall of the cold-rolled finished pipe is 4.5, 5.0 and 5.5 respectively, Figure 18 , Figure 19 and Figure 20 The grain structures of the inner wall, core and outer wall of the finished pipe rolled by 1000 mm cold roll are shown respectively. It can be seen that increasing the diameter of the cold rolling roll of the finished pipe has a good beneficial effect on refining the grains in the core of the pipe wall. Further control the roll diameter between 700-1200mm, the grain size of the finished pipe can be controlled at 5.0 and above.

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Abstract

The invention provides a manufacturing method for a large-diameter austenitic stainless steel thick-wall pipe, and belongs to the technical field of stainless steel machining. The manufacturing method includes the steps of integration of an electric furnace, AOD and centrifugal casting, hot rolling, homogenized heat treatment, primary cold rolling, structure regulation heat treatment, finished pipe cold rolling, solid solution heat treatment and the like. A large-wall-thickness centrifugal casting hollow pipe blank is used as a billet pipe, so that the manufacturing procedure of a billet pipe is omitted, and the yield is increased. The uniformity of the structure and performance in the pipe wall thickness direction is improved through high-temperature homogenized heat treatment of the hot-rolled pipe blank, and the deformation uniformity in the wall thickness direction in the follow-up cold rolling deformation process is improved. Through structure regulation annealing heat treatment and the pinning effect of the second phase, the cold-rolled pipe blank with the uniform and fine grain structure is obtained, so that the large-diameter thick-wall finished pipe with the grain size being higher than the 4.0 level is obtained. Furthermore, the finished pipe is rolled through a superlarge-diameter roller, the better uniform deformation in the wall thickness direction is achieved, and thus the large-diameter thick-wall finished pipe with the grain size being higher than the 5.0 level is obtained.

Description

technical field [0001] The invention belongs to the technical field of manufacturing stainless steel pipes, in particular to the manufacture of austenitic stainless steel large-diameter thick-walled pipes. Background technique [0002] Austenitic stainless steel has been widely used due to its good mechanical properties, corrosion resistance and cold and hot workability. For austenitic stainless steel large-diameter thick-walled pipes with a diameter of more than 300mm and a wall thickness of more than 30mm, they are generally manufactured by forging solid (hollow) billet + machining. Low efficiency, long production cycle and high cost. The production of austenitic stainless steel large-diameter pipes by centrifugal billet + hot rolling has been widely used due to its simple production process and high yield. However, due to the deformation characteristics of the current Pilger hot rolling mill, the thickness of the pipe wall is less than 60mm. If it exceeds 60mm, it is ea...

Claims

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Application Information

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IPC IPC(8): B21C37/06B21B37/78C21D8/10
CPCB21B37/78B21C37/06C21D8/105
Inventor 陈海涛郎宇平屈华鹏
Owner CENT IRON & STEEL RES INST
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