Pickling-free high-strength spring steel and preparation method thereof
By adopting the preparation method of non-picking in the spring steel manufacturing process, including preheating, hot rolling, wire drawing, quenching and tempering, the high cost and environmental protection problems of the traditional pickling process are solved, and the preparation of high-strength spring steel is realized.
Patent Information
- Application Number
- CN202510133566.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2025-04-15
AI Technical Summary
In traditional spring steel manufacturing process, pickling is required after hot processing to remove the scale, but the pickling process consumes a lot of chemical reagents, increasing equipment investment and maintenance costs, and the problem of waste acid treatment leads to environmental pressure and economic burden.
The preparation method of high-strength spring steel without pickling is adopted, including preheating, hot rolling, wire drawing, quenching and tempering, and the pickling process is avoided through specific heating processes and component adjustments.
It realizes the acquisition of high-strength spring steel without pickling, reduces the cost of chemical reagent use and waste acid treatment, reduces equipment damage and environmental protection pressure, and improves the quality and service life of the steel.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of metal materials, and in particular to a pickling-free high-strength spring steel and a preparation method thereof. Background Art
[0002] In the traditional manufacturing process of spring steel, pickling has always occupied an important position. Pickling is usually carried out after hot working processes such as forging or rolling. Its purpose is to remove impurities such as oxide scale and rust formed on the surface of spring steel due to hot working, so that the thickness of the oxide scale is reduced to less than 5μm. For example, in the common hot-rolled strip steel process, after the steel billet is rolled at high temperature, the surface will be covered with a thick and dense layer of oxide scale, which not only seriously affects the surface quality of the steel, making the surface rough and dark in color, but also greatly hinders subsequent processing steps such as phosphating and electroplating. Because if there is oxide scale on the surface, the adhesion of the phosphating film will be significantly deteriorated, and the electroplating layer will be difficult to adhere evenly, and thus it will not be able to fully exert its functions of improving corrosion resistance and lubricity, which will ultimately affect the comprehensive performance and service life of the spring steel product.
[0003] However, the pickling process has many disadvantages. On the one hand, the pickling process requires the use of a large amount of acid, generally hydrochloric acid or sulfuric acid solution, which not only consumes a lot of chemical reagent costs, but also the acid is highly corrosive, requiring extremely high protection of the equipment, increasing equipment investment and maintenance costs. For example, equipment parts such as pickling tanks and pipelines that have been in contact with acid for a long time are easily corroded and damaged, and need to be replaced frequently, resulting in a significant increase in production costs. On the other hand, the treatment of waste acid after pickling has become a thorny problem. Waste acid contains a large amount of dissolved metal ions and unreacted acid. If it is directly discharged, it will cause serious pollution to the environment and violate environmental protection regulations. In order to meet emission standards, enterprises need to be equipped with complex and expensive waste acid treatment facilities to carry out a series of treatment processes such as neutralization, precipitation, and filtration, which further increases the economic burden and environmental pressure of enterprises.
[0004] In view of the above problems of pickling process, technicians in this field have been committed to finding an effective method to replace pickling. In recent years, with the continuous improvement of spring steel performance requirements and the increasing awareness of environmental protection, it is urgent to develop a new technology that can avoid the disadvantages of pickling and ensure the strength of spring steel. Summary of the invention
[0005] The invention provides a pickling-free high-strength spring steel and a preparation method thereof, which solves the problem of pickling after hot rolling in the related art.
[0006] The technical solution of the present invention is as follows: The present invention provides a method for preparing pickling-free high-strength spring steel, comprising the following steps: S1, preheating the steel billet to obtain a preheated steel billet; S2, heating, hot rolling, wire drawing, quenching and tempering the preheated steel billet to obtain spring steel; The heating includes three stages. In the first stage, the heating temperature is increased at a rate of 20-25°C / min, the temperature is heated to 680-720°C, and the temperature is kept warm for 10-15 minutes. In the second stage, the heating temperature is increased at a rate of 12-19°C / min, the temperature is heated to 900-950°C, and the temperature is kept warm for 10-15 minutes. In the third stage, the heating temperature is increased at a rate of 8-11°C / min, the temperature is heated to 1000-1050°C, and the temperature is kept warm for 50-70 minutes.
[0007] As a further technical solution, the preheating temperature is 500-550° C. and the preheating time is 15-30 minutes.
[0008] As a further technical solution, the hot rolling temperature is 950-980°C.
[0009] As a further technical solution, the wire drawing temperature is 820~860°C.
[0010] As a further technical solution, the quenching is to keep the temperature at 800-820°C for 45 minutes and then cool to room temperature with 30°C oil.
[0011] As a further technical solution, the tempering is to keep the quenched steel at 400-450°C for 45 minutes and then cool it to room temperature.
[0012] The present invention also provides an acid-free high-strength spring steel, which is prepared by the acid-free high-strength spring steel preparation method and consists of the following components in percentage by weight: 0.80% to 0.85% carbon, 0.02% to 0.05% silicon, 0.2% to 0.7% aluminum, 0.1% to 0.7% manganese, 2.2% to 4.8% zirconium, 1.8% to 4.2% molybdenum, 0.0002% to 0.0025% phosphorus, 0.0002% to 0.0033% sulfur, and the balance is iron and unavoidable impurities.
[0013] As a further technical solution, the weight ratio of zirconium to molybdenum is 1~2:1.
[0014] In the present invention, the yield strength of the spring steel is improved by adjusting the weight ratio of zirconium to molybdenum to 1-2:1.
[0015] As a further technical solution, the weight ratio of zirconium to molybdenum is 1.5:1.
[0016] In the present invention, the yield strength of the spring steel is further improved by adjusting the weight ratio of zirconium to molybdenum to 1.5:1.
[0017] As a further technical solution, according to the test method in GB / T 228.1-2021, the yield strength of the spring steel is greater than 2000 MPa.
[0018] The working principle and beneficial effects of the present invention are: 1. In the present invention, preheating causes the steel to heat up slowly, which helps to reduce the thermal stress inside the steel. When the steel enters a high temperature environment directly from room temperature, due to the large temperature difference between the inside and outside, a large thermal stress will be generated. The preheating process allows the crystal structure inside the steel to gradually adapt to the temperature change, thereby reducing the generation of thermal stress and avoiding defects such as cracks in the steel during subsequent processing.
[0019] 2. In the present invention, a specific heating process is used to reduce the thickness of the scale layer, thereby eliminating the pickling process.
[0020] 3. In the present invention, hot rolling refines the grains of the steel. Under the action of rolling pressure, the grains inside the steel are elongated and broken along the rolling direction, and then form fine new grains through the recrystallization process. Grain refinement can effectively improve the strength and toughness of spring steel. At the same time, the hot rolling process can also make the steel structure more dense, reduce internal defects such as pores and looseness, and further improve the quality of spring steel.
[0021] 4. In the present invention, wire drawing is to further process the hot-rolled spring steel material into a thinner wire material. This can accurately control the diameter of the spring steel wire to meet the production requirements of springs of different specifications. DETAILED DESCRIPTION
[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0023] Example 1 A method for preparing pickling-free high-strength spring steel comprises the following steps: S1. The steel billet is preheated at 550°C for 15 minutes to obtain a preheated steel billet; S2, heating the preheated steel billet, hot rolling at 980° C., wire drawing at 860° C., quenching, and tempering to obtain spring steel; The heating process includes three stages. In the first stage, the heating temperature is increased at a rate of 25°C / min to 720°C and kept warm for 10 minutes. In the second stage, the heating temperature is increased at a rate of 19°C / min to 950°C and kept warm for 10 minutes. In the third stage, the heating temperature is increased at a rate of 11°C / min to 1050°C and kept warm for 50 minutes.
[0024] The quenching was carried out by keeping the temperature at 820°C for 45 min and cooling to room temperature with 30°C water; Tempering is to keep the quenched steel at 450°C for 45 minutes and then cool it to room temperature; The spring steel raw material is composed of the following components in percentage by weight: 0.85% carbon, 0.05% silicon, 0.7% aluminum, 0.7% manganese, 4.8% zirconium, 1.8% molybdenum, 0.0025% phosphorus, 0.0033% sulfur, and the balance is iron and inevitable impurities.
[0025] Example 2 A method for preparing pickling-free high-strength spring steel comprises the following steps: S1. The steel billet is preheated at 500°C for 30 minutes to obtain a preheated steel billet; S2, heating the preheated steel billet, hot rolling at 950° C., wire drawing at 820° C., quenching, and tempering to obtain spring steel; The heating process includes three stages. In the first stage, the heating temperature is increased at a rate of 20°C / min to 680°C and kept warm for 15 minutes. In the second stage, the heating temperature is increased at a rate of 12°C / min to 900°C and kept warm for 15 minutes. In the third stage, the heating temperature is increased at a rate of 8°C / min to 1000°C and kept warm for 70 minutes.
[0026] The quenching was carried out by keeping the temperature at 800°C for 45 min and cooling to room temperature with 30°C water; Tempering is to keep the quenched steel at 400°C for 45 minutes and then cool it to room temperature; The spring steel raw material is composed of the following components in percentage by weight: 0.80% carbon, 0.02% silicon, 0.2% aluminum, 0.1% manganese, 2.2% zirconium, 4.2% molybdenum, 0.0002% phosphorus, 0.0002% sulfur, and the balance is iron and inevitable impurities.
[0027] Example 3 A method for preparing pickling-free high-strength spring steel comprises the following steps: S1. The steel billet is preheated at 530°C for 20 minutes to obtain a preheated steel billet; S2, heating the preheated steel billet, hot rolling at 960° C., wire drawing at 840° C., quenching, and tempering to obtain spring steel; The heating process includes three stages. In the first stage, the heating temperature is increased at a rate of 24°C / min to 700°C and kept warm for 12 minutes. In the second stage, the heating temperature is increased at a rate of 15°C / min to 930°C and kept warm for 13 minutes. In the third stage, the heating temperature is increased at a rate of 9°C / min to 1030°C and kept warm for 60 minutes.
[0028] The quenching was carried out by keeping the temperature at 810°C for 45 min and cooling to room temperature with 30°C water; Tempering is to keep the quenched steel at 470℃ for 45min and then cool it to room temperature; The spring steel raw material is composed of the following components in percentage by weight: 0.83% carbon, 0.03% silicon, 0.5% aluminum, 0.4% manganese, 4.1% zirconium, 1.9% molybdenum, 0.0008% phosphorus, 0.0012% sulfur, and the balance is iron and inevitable impurities.
[0029] Example 4 The only difference between this embodiment and embodiment 3 is that the spring steel raw material of this embodiment is composed of the following components in percentage by weight: 0.83% carbon, 0.03% silicon, 0.5% aluminum, 0.4% manganese, 2.8% zirconium, 3.2% molybdenum, 0.0008% phosphorus, 0.0012% sulfur, and the balance is iron and unavoidable impurities.
[0030] Example 5 The only difference between this embodiment and embodiment 3 is that the spring steel raw material of this embodiment is composed of the following components in percentage by weight: 0.83% carbon, 0.03% silicon, 0.5% aluminum, 0.4% manganese, 3.0% zirconium, 3.0% molybdenum, 0.0008% phosphorus, 0.0012% sulfur, and the balance is iron and unavoidable impurities.
[0031] Example 6 The only difference between this embodiment and embodiment 3 is that the spring steel raw material of this embodiment is composed of the following components in percentage by weight: 0.83% carbon, 0.03% silicon, 0.5% aluminum, 0.4% manganese, 3.6% zirconium, 2.4% molybdenum, 0.0008% phosphorus, 0.0012% sulfur, and the balance is iron and unavoidable impurities.
[0032] Example 7 The only difference between this embodiment and embodiment 3 is that the spring steel raw material of this embodiment is composed of the following components in percentage by weight: 0.83% carbon, 0.03% silicon, 0.5% aluminum, 0.4% manganese, 4.0% zirconium, 2.0% molybdenum, 0.0008% phosphorus, 0.0012% sulfur, and the balance is iron and unavoidable impurities.
[0033] Comparative Example 1 The only difference between this comparative example and Example 2 is that the heating in this comparative example includes three stages. In the first stage, the heating temperature rise rate is 26°C / min, heating to 680°C and keeping warm for 15 minutes; in the second stage, the heating temperature rise rate is 12°C / min, heating to 900°C and keeping warm for 15 minutes; in the third stage, the heating temperature rise rate is 8°C / min, heating to 1000°C and keeping warm for 70 minutes.
[0034] Comparative Example 2 The only difference between this comparative example and Example 2 is that the heating in this comparative example includes three stages. In the first stage, the heating temperature rise rate is 19°C / min, heating to 680°C and keeping warm for 15 minutes; in the second stage, the heating temperature rise rate is 12°C / min, heating to 900°C and keeping warm for 15 minutes; in the third stage, the heating temperature rise rate is 8°C / min, heating to 1000°C and keeping warm for 70 minutes.
[0035] Comparative Example 3 The only difference between this comparative example and Example 2 is that the heating includes three stages. In the first stage, the heating temperature rise rate is 20°C / min, heating to 680°C and keeping warm for 15 minutes; in the second stage, the heating temperature rise rate is 11°C / min, heating to 900°C and keeping warm for 15 minutes; in the third stage, the heating temperature rise rate is 8°C / min, heating to 1000°C and keeping warm for 70 minutes.
[0036] Comparative Example 4 The only difference between this comparative example and Example 2 is that the heating includes three stages. In the first stage, the heating temperature is increased at a rate of 20°C / min, heated to 680°C, and kept warm for 15 minutes; in the second stage, the heating temperature is increased at a rate of 20°C / min, heated to 900°C, and kept warm for 15 minutes; in the third stage, the heating temperature is increased at a rate of 8°C / min, heated to 1000°C, and kept warm for 70 minutes.
[0037] Comparative Example 5 The only difference between this comparative example and Example 2 is that the heating includes three stages. In the first stage, the heating temperature is increased at a rate of 20°C / min, heated to 680°C, and kept warm for 15 minutes; in the second stage, the heating temperature is increased at a rate of 12°C / min, heated to 900°C, and kept warm for 15 minutes; in the third stage, the heating temperature is increased at a rate of 12°C / min, heated to 1000°C, and kept warm for 70 minutes.
[0038] Comparative Example 6 The only difference between this comparative example and Example 2 is that the heating includes three stages. In the first stage, the heating temperature is increased at a rate of 20°C / min, and the temperature is heated to 680°C and kept warm for 15 minutes. In the second stage, the heating temperature is increased at a rate of 12°C / min, and the temperature is heated to 900°C and kept warm for 15 minutes. In the third stage, the heating temperature is increased at a rate of 7°C / min, and the temperature is heated to 1000°C and kept warm for 70 minutes.
[0039] Experimental Example 1 The iron oxide scale on the surface of the hot-rolled steel billets in Examples 1 to 3 and Comparative Examples 1 to 6 was tested by electron microscope scanning. The test results are shown in Table 1.
[0040]
[0041] Comparing Example 2 with Comparative Examples 1 to 6, it is shown that the specific heating rate selected in the present invention can make the thickness of the oxide scale generated on the steel billet after hot rolling reach less than 3 μm, and pickling can be avoided.
[0042] Experimental Example 2 The yield strength of Examples 1 to 7 and the prepared spring steel was tested according to the method specified in GB / T 228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method", and the test results are shown in Table 2:
[0043] Comparing Examples 5 to 7 with Examples 3 to 4, it is shown that when the weight ratio of zirconium to molybdenum in the spring steel raw material is 1 to 2:1, the yield strength of the spring steel is improved; comparing Example 6 with Examples 5 and 7, it is shown that when the weight ratio of zirconium to molybdenum is 1.5:1, the yield strength of the spring steel is best improved.
[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing pickling-free high-strength spring steel, characterized in that: The following steps are involved: S1, preheating the steel billet to obtain a preheated steel billet; S2, heating, hot rolling, wire drawing, quenching and tempering the preheated steel billet to obtain spring steel; The heating includes three stages. In the first stage, the heating temperature is increased at a rate of 20-25°C / min, the temperature is heated to 680-720°C, and the temperature is kept warm for 10-15 minutes. In the second stage, the heating temperature is increased at a rate of 12-19°C / min, the temperature is heated to 900-950°C, and the temperature is kept warm for 10-15 minutes. In the third stage, the heating temperature is increased at a rate of 8-11°C / min, the temperature is heated to 1000-1050°C, and the temperature is kept warm for 50-70 minutes.
2. The method for preparing pickling-free high-strength spring steel according to claim 1, characterized in that: The preheating temperature is 500-550° C. and the preheating time is 15-30 minutes.
3. The method for preparing pickling-free high-strength spring steel according to claim 1, characterized in that: The hot rolling temperature is 950-980°C.
4. The method for preparing pickling-free high-strength spring steel according to claim 1, characterized in that: The wire drawing temperature is 820-860°C.
5. The method for preparing pickling-free high-strength spring steel according to claim 1, characterized in that: The quenching is performed by keeping the temperature at 800-820° C. for 45 minutes and then cooling the temperature to room temperature with water at 30° C.
6. The method for preparing pickling-free high-strength spring steel according to claim 1, characterized in that: The tempering is to keep the quenched steel at 400-450° C. for 45 minutes and then cool it to room temperature.
7. A pickling-free high-strength spring steel, prepared by the method for preparing a pickling-free high-strength spring steel according to any one of claims 1 to 6, characterized in that: It is composed of the following components in percentage by weight: 0.80% to 0.85% carbon, 0.02% to 0.05% silicon, 0.2% to 0.7% aluminum, 0.1% to 0.7% manganese, 2.2% to 4.8% zirconium, 1.8% to 4.2% molybdenum, 0.0002% to 0.0025% phosphorus, 0.0002% to 0.0033% sulfur, and the balance is iron and inevitable impurities.
8. The pickling-free high-strength spring steel according to claim 7, characterized in that: The weight ratio of zirconium to molybdenum is 1-2:
1.
9. The pickling-free high-strength spring steel according to claim 8, characterized in that: The weight ratio of zirconium to molybdenum is 1.5:
1.
10. The pickling-free high-strength spring steel according to claim 7, characterized in that: According to the test method in GB / T 228.1-2021, the yield strength of the spring steel is greater than 2000 MPa.