Manufacturing method of structural steel

A manufacturing method and technology for structural steel are applied in the field of steel material manufacturing to achieve the effects of simple process, low energy consumption and simple cooling process

Inactive Publication Date: 2014-05-07
吴雪
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the original Q345 production method can no longer meet the requirements, and a new production process needs to be formulated according to the characteristics of boron-added steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] A method for manufacturing structural steel according to the present invention, the chemical composition of the materials used is shown in Table 1.

[0018] Heat the sample to 1200°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. The obtained 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.

[0019]

[0020] Table 1 Chemical composition of boron-containing structural steel Q345 (mass fraction, %)

[0021] C Si mn P S B 0.17 0.25 0.80 0.015 0.003 0.0018

Embodiment 2

[0023] A method for manufacturing structural steel according to the present invention, the materials used are the same as in Example 1, the final cooling temperature in Example 1 is increased to 650°C in the controlled cooling process, and the strain rate of all deformation passes is 3s -1 . The obtained room temperature microstructure 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.

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PUM

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Abstract

The invention discloses a manufacturing method of structural steel; through a controlled rolling and controlled cooling process and by utilizing the equilibrium relationship between shape change and phase change, carbon and boron in ferrite diffuse into austenite in the phase change incubation period under the condition that the phase transformation nucleation points are increased, so that the phase change period can be shortened. The boron-contained structural steel contains the following chemical components by weight: 0.08-0.20% of C, 0.10-0.30% of Si, 0.80-1.50% of Mn, less than or equal to 0.010% of P, less than or equal to 0.010% of S, 0.0008-0.0030% of B, and the balance of Fe and inevitable impurities. The boron-contained structural steel obtained through the invention is homogeneous in structure, small in grain and good in obdurability.

Description

[0001] technical field [0002] The invention belongs to the field of iron and steel material manufacturing, in particular to a method for manufacturing structural steel. Background technique [0003] In alloy structural steel, in order to reduce production costs, the content of precious alloy elements Ni, Cr, Mo, etc. is generally reduced, and some special alloy elements are appropriately added. 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". [0004] The addition of a small amount of boron to boron steel not only reduces the formation rate of ferrite during continuous cooling of austenite, but also prolongs the prec...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/04C21D8/00
Inventor 吴雪
Owner 吴雪
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