Heating control method for reducing decarburization of spring steel for automobile stabilizer bar

Abstract

The invention discloses a heating control method for reducing decarburization of spring steel for an automobile stabilizer bar, which comprises the following steps of: 1) controlling the total heating time of a blank in a heating furnace to 180-250 minutes through an in-furnace steel loading empty step; (2) the temperature of the second heating section is controlled to be 950-1060 DEG C, and the soaking temperature is controlled to be 1060-1120 DEG C; by controlling the number of the blanks in the furnace, shortening the heating time and reducing the heating temperature, surface decarburization of the spring steel can be reduced, even zero decarburization is achieved, the production cost is reduced, and the delivery rate is increased.

Description

Technical Field

[0001] The invention relates to spring steel, in particular to a heating control method for reducing decarburization of spring steel used for automobile stabilizer bars. Background Art

[0002] At present, spring steel is more and more widely used in various fields in China. Spring steel has a high elastic limit and load-bearing capacity, plays a role in buffering and shock absorption, and has particularly high requirements for fatigue performance. Surface decarburization has a great damage to the fatigue performance of springs, especially for some precision spring products such as spring steel for automobile stabilizer bars. The surface is not allowed to have a full decarburization layer, and the raw materials are delivered with zero decarburization. Nanjing Iron and Steel Medium Rod Factory has a heating furnace with a total length of 42.6 meters and a billet of 250mm×300mm×11000mm. The production of small-sized spring steel is slow, and it is generally heated in the furnace for more than 5 hours before being taken out of the furnace. The surface decarburization layer of the finished product is thick, and surface peeling is usually required to achieve zero decarburization delivery; in production, the surface peeling of the billet or painting of the billet surface is usually used to reduce decarburization, which not only increases production costs, but also has a certain impact on the environment. Summary of the invention

[0003] Purpose of the invention: In view of the shortcomings and defects of the prior art, the present invention provides a heating control method for reducing decarburization of spring steel for automobile stabilizer bars. By controlling the number of blanks in the furnace, shortening the heating time and lowering the heating temperature, the surface decarburization of the spring steel can be reduced or even reach zero decarburization, which not only reduces the production cost but also improves the delivery rate.

[0004] Technical solution: A heating control method for reducing decarburization of spring steel for automobile stabilizer bars of the present invention is characterized in that it includes the following steps: 1) by loading steel into the furnace in an empty step, the total heating time of the blank in the heating furnace is controlled to be 180min-250min; 2) the temperature of the second heating stage is controlled to be 950℃-1060℃, and the soaking temperature is controlled to be 1060℃-1120℃.

[0005] Among them, in the step 1) of steel loading and emptying in the furnace, for Φ16mm, the steel tapping rhythm is >254s, the steel loading and emptying step requirements are 1 loading and 3 emptying, and the machine hourly output is ≤84 tons / h.

[0006] Among them, in the step 1) of steel loading and emptying in the furnace, for Φ17mm-22mm, the steel tapping rhythm is 196s-254s, the steel loading and emptying step requirement is 1 loading and 2 emptying, and the machine hourly output is 85 tons / h-109 tons / h.

[0007] Among them, in the step 1) of steel loading and emptying in the furnace, for Φ23mm-30mm, the steel tapping rhythm is 144s-196s, the steel loading and emptying step requirements are 1 loading and 2 emptying, and the machine hourly output is 110 tons / h-150 tons / h.

[0008] Wherein, the total heating time in step 1) includes the heating time of the preheating section, the heating time of the heating section and the heating time of the soaking section.

[0009] Among them, the heating time of the preheating section is 60 minutes, the heating time of the heating section is 60 minutes-90 minutes, and the heating time of the soaking section is 60 minutes.

[0010] Wherein, the heating temperature of the preheating section is ≤800°C.

[0011] Wherein, the heating section includes a first heating section and a second heating section, and the soaking section includes a first soaking section and a second soaking section.

[0012] Wherein, the temperature of the first heating stage is ≤950°C, and the temperature of the second heating stage is 950°C-1050°C.

[0013] Wherein, the temperature of the first stage of the equalization is 1060°C-1120°C, and the temperature of the second stage of the equalization is 1080°C-1120°C.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention reduces the surface decarburization problem of spring steel for automobile stabilizer bars with a bar grade of Φ16mm-30mm 55Cr3 and SUP9D; the total decarburization layer of the spring steel is controlled to be 0.08mm-0.15mm; the total decarburization layer on the surface of the spring steel is 0. The present invention can reduce the surface decarburization of the spring steel or even achieve zero decarburization by controlling the number of blanks in the furnace, reducing the heating time and the heating temperature, which not only reduces the production cost, but also improves the delivery rate. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0016] The heating control method for reducing decarburization of spring steel for automobile stabilizer bars of the present invention comprises the following steps:

[0017] 1) Through the steel-loading and emptying steps in the furnace, the total heating time of the billet in the heating furnace is controlled within 180min-250min. In the steel-loading and emptying steps in the furnace, for Φ16mm, the steel-out rhythm is greater than 254s, the steel-loading and emptying steps are required to be 1 for loading and 3 for emptying, and the machine-hour output is ≤84 tons / h; for Φ17mm-22mm, the steel-out rhythm is 196s-254s, the steel-loading and emptying steps are required to be 1 for loading and 2 for emptying, and the machine-hour output is 85 tons / h-109 tons / h; for Φ23mm-30mm, the steel-out rhythm is 144s-196s, the steel-loading and emptying steps are required to be 1 for loading and 2 for emptying, and the machine-hour output is 110 tons / h-150 tons / h.

[0018]

[0019] By controlling the empty step of steel loading, the preheating time in the heating furnace is controlled at 60 minutes, and the heating time is controlled at 60-90 minutes; the soaking time is controlled at about 60 minutes, reducing the time the billet spends in the high temperature section, which can effectively prevent the carbon atoms on the billet surface from reacting with the oxygen atoms in the furnace gas at high temperature, reducing decarburization on the surface of the finished product, and at the same time will not affect production efficiency.

[0020] 2) The temperature of the second heating stage is controlled at 950℃-1060℃, and the absorptive temperature is controlled at 1000℃-1120℃. The heating temperature of the preheating stage is ≤800℃. The heating stage includes the first heating stage and the second heating stage, and the absorptive stage includes the first absorptive stage and the second absorptive stage. The temperature of the first heating stage is ≤950℃, and the temperature of the second heating stage is 950℃-1050℃. The temperature of the first absorptive stage is 1060℃-1120℃, and the temperature of the second absorptive stage is 1080℃-1120℃.

[0021]

[0022] After the billet enters the second heating stage, low-temperature heating is adopted to reduce the residence time of the billet in the high-temperature stage, avoid decarburization of carbon atoms on the surface of the steel billet at high temperature, and thus reduce the thickness of the decarburization layer on the surface of the finished product.

[0023] Chemical composition of spring steel: C: 0.56%-0.69%, Si: 0.25%-0.35%, Mn: 0.80%-0.88%, Cr: 0.80%-0.88%, Ni+Cu≤0.20%, P+S≤0.025%, balance Fe.

[0024] The present invention shortens the heating time of the blank in the furnace by controlling the steel loading empty step, and reduces the heating temperature at the same time. While ensuring the temperature uniformity of the blank, the oxidation reaction between the carbon atoms on the surface of the blank and the oxygen atoms in the furnace gas is reduced, so that the total decarburization layer thickness on the surface of the product is controlled within 0.08mm-0.15mm, and the total decarburization layer is 0; the fatigue strength of the spring steel is improved, the decarburization layer on the surface of the spring steel is reduced, and the total decarburization layer is 0, which not only reduces the production cost, but also improves the delivery rate. It has a high use value.

Claims

1. A heating control method for reducing decarburization of spring steel for automobile stabilizer bars, characterized in that: The method comprises the following steps: 1) controlling the total heating time of the blank in the heating furnace to be 180-250 minutes by loading the furnace with steel; 2) controlling the temperature of the second heating stage to be 950-1060°C, and the ambulation temperature to be 1060-1120°C.

2. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 1, characterized in that: In the step 1) of steel loading and emptying in the furnace, for Φ16mm, the steel tapping rhythm is >254s, the steel loading and emptying step requirements are 1 loading and 3 emptying, and the machine hourly output is ≤84 tons / h.

3. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 2, characterized in that: In the step 1), in the steel-loading empty step in the furnace, for Φ17mm-22mm, the steel-out rhythm is 196s-254s, the steel-loading empty step requirement is 1 loading and 2 emptying, and the machine hourly output is 85 tons / h-109 tons / h.

4. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 3, characterized in that: In the step 1), in the steel-loading empty step in the furnace, for Φ23mm-30mm, the steel-out rhythm is 144s-196s, the steel-loading empty step requirement is 1 loading and 2 emptying, and the machine hourly output is 110 tons / h-150 tons / h.

5. The heating control method for reducing decarburization of spring steel for automobile stabilizer bar according to claim 1, characterized in that: The total heating time in step 1) includes the preheating section heating time, the heating section heating time and the soaking section heating time.

6. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 5, characterized in that: The heating time of the preheating section is 60 minutes, the heating time of the heating section is 60 minutes-90 minutes, and the heating time of the soaking section is 60 minutes.

7. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 6, characterized in that: The heating temperature of the preheating section is ≤800°C.

8. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 6, characterized in that: The heating section includes a first heating section and a second heating section, and the soaking section includes a first soaking section and a second soaking section.

9. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 8, characterized in that: The temperature of the first heating stage is ≤950°C, and the temperature of the second heating stage is 950°C-1050°C.

10. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 8, characterized in that: The temperature of the first stage of the equalization is 1060°C-1120°C, and the temperature of the second stage of the equalization is 1080°C-1120°C.

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