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Medium carbon steel and its production process

A production process, carbon steel technology, applied in the direction of manufacturing tools, metal processing equipment, rolling mill control devices, etc., can solve problems such as stress concentration, reduce material fatigue limit, product failure and fracture

Active Publication Date: 2021-08-03
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 its production process
  • Medium carbon steel and its production process
  • Medium carbon steel and its production process

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 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 is 1096...

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Abstract

The application relates to a medium carbon steel and a production process thereof, belonging to the technical field of production technology of medium carbon steel. The production process of medium carbon steel includes: four-stage heating and rolling of continuous casting or rolling billets, and then cooling the rolled steel to obtain uniform ferrite and pearlite structures. In the four-stage heating, the heating temperature of the second heating stage is 1100±15℃, and the heating time is D×(0.15‑0.25)min. The heating temperature of the soaking section is 1090±15℃, and the heating time is D×(0.10‑0.20)min. By controlling the heating temperature of each stage, the heating time of the high temperature section and the cooling method, the ferrite and pearlite transformation areas on the steel surface can fully form ferrite and pearlite with uniform grains and uniform structure, so as to reduce the desorption of steel. Carbon tendency, the total decarburization layer depth of medium carbon steel is controlled within 0.30mm or 0.4%Dmm, and the hardness is less than or equal to 260HBW.

Description

technical field [0001] The application relates to the technical field of medium carbon steel production technology, and in particular to a medium carbon steel and its production process. Background technique [0002] Decarburization is a common surface defect of medium carbon steel, and the carbon content on the surface will decrease compared with 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 are quenching soft spots. In the subsequent application process, in the presence of alternating stress, the material Will be prone to cracks, making it 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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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