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Preparation method of boron-containing structural steel

A manufacturing method and technology of structural steel, which is applied in the field of steel material manufacturing, can solve problems such as large differences in structure, and achieve the effects of low cost, improved toughness, and improved performance

Inactive Publication Date: 2011-06-01
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the problem that the existing method produces boron-added Q345 steel with relatively large structure differences, the purpose of the present invention is to provide a method for manufacturing boron-containing structural steel

Method used

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  • Preparation method of boron-containing structural steel

Examples

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Effect test

Embodiment 1

[0024] A method for manufacturing boron-containing structural steel according to the present invention, the chemical composition of the materials used is shown in Table 1.

[0025] Heat the sample to 1175°C and hold it for 5 minutes. After it is completely austenitized, cool it to 1000°C, 850°C, and 780°C at a cooling rate of 5°C / s. %, 33.3%, 50%, single pass compression test, the strain rate of all deformation passes is 1s -1 . Then carry out 5°C / s controlled cooling method to cool down to 600°C, and finally place it in air for cooling. obtained organizations such as figure 1 shown. From figure 1 It can be seen that the structure is composed of a large number of polygonal ferrite and granular bainite, the grain size is small, and a small amount of pearlite is distributed on the polygonal ferrite.

[0026]

Embodiment 2

[0028] A method for manufacturing boron-containing structural steel according to the present invention, the material used is the same as in Example 1, the final cooling temperature in Example 1 is increased to 630°C in the controlled cooling process, and the strain rate of all deformation passes is 3s -1 . The obtained room temperature tissue is as figure 2 shown. The obtained structure is also composed of polygonal ferrite, acicular ferrite, pearlite and a large number of clustered granular bainite. Compared with Example 1, the grain size does not change much, and the acicular ferrite increases a lot , the volume fraction of pearlite increases.

Embodiment 3

[0030] A method for manufacturing boron-containing structural steel according to the present invention, the materials used are the same as in Examples 1 and 2, the final cooling temperature is increased to 660°C in the controlled cooling process, and the strain rate of all deformation passes is 5s -1 . The obtained room temperature tissue is as image 3 shown. The obtained structure is composed of a large amount of ferrite, a small amount of polygonal ferrite, a very small amount of pearlite and granular bainite, and the grain size is increased compared with Examples 1 and 2, but the increase is not obvious.

[0031] It can be seen that the boron-containing steel obtained according to the present invention has excellent structure and properties, fine grain size, average grain size of ferrite less than 5 μm, simple process and low cost.

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Abstract

The invention discloses a preparation method of boron-containing structural steel. The boron-containing structural steel comprises the following chemical components by weight percent: 0.08-0.20% of C, 0.10-0.30% of Si, 0.80-1.50% of Mn, no more than 0.010% of P, no more than 0.010% of S, 0.0008-0.0030% of B and the balance of Fe and inevitable impurities. The preparation method comprises the following specific steps: heating to 1175-1225 DEG C for austenitization, and then performing multipass rolling, wherein the deformation temperature is between the austenitic recrystallization region and austenitic unrecrystallization region and the austenite-ferrite two-phase region; and then cooling to 600-660 DEG C at a cooling rate of 1-10 DEG C / s, and then performing air cooling. The boron-containing structural steel prepared by the method provided by the invention mainly contains ferrite, bainite and a small amount of pearlite. The structural steel has the advantages of uniform structure, fine grain and good strength and toughness.

Description

technical field [0001] The invention belongs to the field of iron and steel material manufacturing, in particular to a method for manufacturing boron-containing structural steel. Background technique [0002] In recent decades, countries in the world have generally reduced the content of precious alloy elements Ni, Cr, Mo, etc. in alloy structural steels in order to reduce production costs, and appropriately added some special alloy elements. The development of boron steel is widely used under such requirements. When 0.0005-0.0050% boron is added to the steel, the hardenability of the steel is greatly improved, and the mechanical properties after heat treatment are improved, so a small amount of boron can replace a large amount of alloying elements (such as Ni, Cr, Mo, etc.), so In the Soviet Union, "boron" was hailed as "the vitamin in steel". A variety of boron steels have been used abroad to manufacture parts that require heat treatment, such as automobiles, aircraft, t...

Claims

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Application Information

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IPC IPC(8): C22C38/04B21B37/74
Inventor 邱红雷李晓玲楚觉非王端军刘朝霞陈远姝宋世佳
Owner NANJING IRON & STEEL CO LTD
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