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Production method of spring flat steel

A production method and flat steel technology, applied in the field of iron and steel production, can solve the problems of large equipment wear, large loss of processing tools, high hardness, etc., and achieve the effects of heat treatment process optimization, composition design optimization, and low hardness

Pending Publication Date: 2022-08-09
HUNAN VALIN XIANGTAN IRON & STEEL CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, there are following problems in the application of high-strength spring flat steel to manufacture leaf springs: the microstructure of high-strength spring flat steel is tempered troostite after quenching+medium temperature tempering treatment, and its hardness is usually very high, resulting in lower The wear of the equipment is relatively large when processing the center hole and the end hole, which increases the processing cost of the leaf spring manufacturer.
[0007] In the above-mentioned patents, in order to ensure that the spring steel has high tensile strength and yield strength, it usually contains a relatively high content of one of C (>0.5%), Mn (>1%), Cr (>1%) or Several kinds, resulting in high hardness of spring steel after quenching + tempering (hardness ≥ 45 HRC), resulting in greater loss of processing tools for leaf spring manufacturers and increasing production costs

Method used

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  • Production method of spring flat steel
  • Production method of spring flat steel
  • Production method of spring flat steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The chemical composition of the steel is C: 0.36%, Si: 1.2%, Mn: 0.3%, Cr: 0.60%, Ni: 0.50%, V: 0.20%, Nb: 0.030%, Al: 0.020%, P: 0.003 %, S: 0.005%, Cu: 0.02%, O: 0.0011%, N: 0.0150%, and the rest are Fe and inevitable impurities. Key process steps include:

[0032] (1) Smelting: During smelting, the converter adopts double-slag carbon-preserving smelting, and the control end point is C=0.17%; the refining adopts high-basicity slag-making and deoxidation process, and Al is adjusted in place at one time in the early stage, and it is strictly forbidden to adjust aluminum in the later stage.

[0033] (2) Continuous casting: The molten steel after smelting is continuously cast to obtain a slab. During continuous casting, the superheat degree of the tundish is 15~25℃, the weak cooling is adopted, the specific water volume is 0.16L / kg, with electromagnetic stirring and light pressing at the end. 24h.

[0034] (3) Rolling: The continuous casting billet is hot rolled into s...

Embodiment 2

[0038]The chemical composition of the steel is C: 0.38%, Si: 1.3%, Mn: 0.3%, Cr: 0.80%, Ni: 0.50%, V: 0.25%, Nb: 0.030%, Al: 0.025%, P: 0.005 %, S: 0.004%, Cu: 0.03%, O: 0.0009%, N: 0.0160%, and the rest are Fe and inevitable impurities. Key process steps include:

[0039] (1) During smelting, the converter adopts double-slag carbon-preserving smelting, and the end-point carbon is controlled at 0.16%; the refining adopts a high-basicity slag-forming and deoxidizing process, and the Al is adjusted in place at one time in the early stage, and it is strictly forbidden to adjust the aluminum in the later stage.

[0040] (2) Continuous casting: The molten steel after smelting is continuously cast to obtain a slab. During continuous casting, the superheat degree of the tundish is 15~25℃, the weak cooling is adopted, the specific water volume is 0.16L / kg, with electromagnetic stirring and light pressing at the end. 24h.

[0041] (3) Rolling: The continuous casting billet is hot ro...

Embodiment 3

[0045] The chemical composition weight percentage and process steps of the steel are basically the same as those in Example 1. The difference is: in step (4), the spring flat steel is heated to 880°C, kept for 60min, oil-cooled to room temperature, and then tempered. The tempering temperature is 410°C, and the water is cooled to room temperature after 120min of heat preservation.

[0046] Use metallographic microscope to observe the microstructure of the spring flat steel obtained in this example, such as image 3 The microstructure shown is tempered troostite. The room temperature tensile test was carried out according to GB / T 228.1-2021, and the mechanical properties were measured. The obtained mechanical properties test results are shown in Table 1.

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Abstract

The invention relates to a production method of spring flat steel with high strength and low hardness. The steel comprises the following chemical components in percentage by weight: 0.35%-0.40% of C, 1.0%-1.3% of Si, 0.2%-0.4% of Mn, 0.50%-0.90% of Cr, 0.20%-0.60% of Ni, 0.10%-0.30% of V, 0.010%-0.050% of Nb, 0.010%-0.050% of Al, less than or equal to 0.020% of P, less than or equal to 0.020% of S, less than or equal to 0.20% of Cu, less than or equal to 0.0020% of O, 0.0090%-0.0200% of N and the balance of Fe and inevitable impurities. The production process comprises the steps of smelting, continuous casting, rolling, cold bed slow cooling, quenching, tempering and the like. By applying the components and the process, the structure of the obtained spring flat steel is tempered troostite, and the tensile strength is gt; the pressure is 1500MPa, and the yield strength is gt; the pressure is 1350 MPa, and the hardness is 40 HRC to 44 HRC.

Description

technical field [0001] The invention belongs to the technical field of iron and steel production, and relates to a production method of spring flat steel with both high strength and low hardness. Background technique [0002] With the continuous upgrading of automobile emission standards, lightweight has become an inevitable trend of automobile development. Leaf spring, referred to as leaf spring, is an important part of the vehicle suspension system, which has the functions of shock absorption and guidance. Due to its simple structure and easy manufacture, leaf springs have been widely used in trucks. The weight of the leaf spring accounts for about 9% of the weight of the whole vehicle. Reducing the weight of the leaf spring is an effective means to realize the lightweight of the vehicle. Increasing the strength of the flat spring steel from which the leaf spring is made can significantly reduce the weight of the leaf spring, because the weight of the leaf spring is inve...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/46C22C38/48C22C38/06C22C38/42C22C33/04C21D1/18C21D8/02B22D11/00
CPCC22C38/02C22C38/04C22C38/46C22C38/48C22C38/06C22C38/42C22C38/001C22C33/04C21D1/18C21D8/0205C21D8/0226C21D8/0247B22D11/001C21D2211/009Y02P10/20
Inventor 郑健张成元张群琥杨奇军刘建杨庚朝王旭冀李建宇杨建华陈礼清赵阳姜政宇
Owner HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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