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Medium carbon steel and production process thereof

A production process and technology of carbon steel, applied in the direction of manufacturing tools, metal processing equipment, rolling mill control devices, etc., can solve problems such as stress concentration, product failure and fracture, and easy cracks in materials, and achieve the effect of improving life and high hardness

Active Publication Date: 2020-08-18
BAOSTEEL SPECIAL STEEL SHAOGUAN CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Medium-carbon steel products generally need to be quenched to obtain higher hardness. Due to the reduction of carbon content, the hardness after quenching is not high, that is, there are quenching soft spots. In the subsequent application process, in the presence of alternating stress, the material Will be prone to cracks, causing premature fatigue failure
In addition, due to decarburization, the carbon content of the surface layer changes gradually, resulting in different coefficients of expansion during quenching at different positions, and different degrees of volume change during tissue transformation, resulting in stress concentration, resulting in direct microcracks in different areas of the surface , these cracks become stress concentration areas, laying hidden dangers for subsequent cracks, eventually causing product failure and fracture, reducing the fatigue limit of materials

Method used

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  • Medium carbon steel and production process thereof
  • Medium carbon steel and production process thereof
  • Medium carbon steel and production process thereof

Examples

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Comparison scheme
Effect test

Embodiment 1

[0042] This embodiment provides a medium-carbon steel and its production process. In terms of mass percentage, the composition of the medium-carbon steel includes C: 0.37%, Si: 0.45%, Mn: 1.35%, P: 0.020%, S: 0.025-0.060 %, Cr: 0.20%, Mo: 0.10%, Al: 0.030%, V: 0.02%, Ti: 0.03%, and the rest is Fe.

[0043] The production process includes:

[0044] 1. Continuous casting slab heating, billet rolling. The thickness D of the rolled slab was 210 mm.

[0045] 2. Rolled billet peeling: two-pass process is used to peel the four rolling surfaces of the billet after billet rolling, the total peeling depth is 1.2mm, the first peeling depth is 0.7mm, the second The peeling depth is 0.5mm.

[0046] 3. Rolled billet heating: four-stage heating process is adopted, the heating temperature of the preheating section is not more than 750°C, the heating temperature of the first heating section is 800±50°C, and the heating temperature of the second heating section and the soaking section is 110...

Embodiment 2

[0050] This embodiment provides a medium-carbon steel and its production process. In terms of mass percentage, the composition of the medium-carbon steel includes C: 0.42%, Si: 0.57%, Mn: 1.37%, P: 0.011%, S: 0.042%, Cr: 0.14%, Mo: 0.03%, Al: 0.017%, V: 0.005%, Ti: 0.004%, and the rest is Fe.

[0051] The production process includes:

[0052] 1. Continuous casting slab heating, billet rolling. The thickness D of the rolled slab was 210 mm.

[0053] 2. Rolled billet peeling: Two-pass process is used to peel the four rolling surfaces of the steel billet after billet rolling. The total peeling depth is 1.3mm. The first peeling depth is 0.8mm, and the second peeling The peeling depth is 0.5mm.

[0054] 3. Rolled billet heating: four-stage heating process is adopted, the heating temperature of the preheating section is not more than 750°C, the heating temperature of the first heating section is 800±50°C, and the heating temperature of the second heating section and the soaking s...

Embodiment 3

[0058] This embodiment provides a medium-carbon steel and its production process. In terms of mass percentage, the composition of the medium-carbon steel includes C: 0.40%, Si: 0.60%, Mn: 1.40%, P: 0.015%, S: 0.055%, Cr: 0.10%, Mo: 0.02%, Al: 0.019%, V: 0.004%, Ti: 0.001%, and the rest is Fe.

[0059] The production process includes:

[0060] 1. Continuous casting slab heating, billet rolling. The thickness D of the rolled slab was 220 mm.

[0061] 2. Rolled billet peeling: Two-pass process is used to peel the four rolling surfaces of the billet after billet rolling. The total peeling depth is 1.1mm. The first peeling depth is 0.6mm, and the second peeling The peeling depth is 0.5mm.

[0062] 3. Rolled billet heating: four-stage heating process is adopted, the heating temperature of the preheating section is not more than 750°C, the heating temperature of the first heating section is 800±50°C, and the heating temperature of the second heating section and the soaking section...

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Abstract

The invention relates to medium carbon steel and a production process thereof, and belongs to the technical field of production processes of medium carbon steel. The production process of the medium carbon steel comprises the steps: performing four-stage heating and rolling on a continuous casting blank or a rolling blank, and then cooling the rolled steel to obtain ferrite and pearlite structureswith uniform structures. In the process of the four-stage heating, a dual-heating stage is performed under the heating temperature of 1100+ / -15 DEG C for D*(0.15-0.25) minutes; and a soaking heatingstage is carried out under the heating temperature of 1090+ / -15 DEG C for D*(0.10-0.20) minutes. By controlling the heating temperature of each stage, the heating time of the high temperature stages and a cooling mode, the ferrite and pearlite transformation areas on the surface of the steel are completely formed into the ferrite and pearlite with the uniform grains and the uniform structures, thedecarburization tendency of the steel is reduced, the total decarburization depth of the medium carbon steel is controlled within 0.30 mm or 0.4% Dmm, and the hardness is less than or equal to 260 HBW.

Description

technical field [0001] The present application relates to the technical field of production technology of medium carbon steel, and particularly relates to a medium carbon steel and a production technology thereof. Background technique [0002] Decarburization is a common surface defect of medium carbon steel, and the carbon content of the surface will decrease relative to the matrix. Medium carbon steel products generally need to be quenched to obtain higher hardness. Due to the reduction of carbon content, the hardness after quenching is not high, that is, there is a quenching soft spot. In the subsequent application process, in the presence of alternating stress, the material Cracks are prone to occur, causing premature fatigue failure. In addition, due to decarburization, the surface carbon content changes in a gradient, resulting in different expansion coefficients during quenching at different positions, and different degrees of volume change during microstructure tran...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/28B21B37/74B21B37/00
CPCB21B37/00B21B37/74C21D2211/005C21D2211/009C22C38/002C22C38/02C22C38/04C22C38/06C22C38/22C22C38/24C22C38/28
Inventor 刘年富杨伟光吴学兴赵贺楠邓湘斌钟芳华周成宏钟凡
Owner BAOSTEEL SPECIAL STEEL SHAOGUAN CO LTD