A heating control method for reducing decarburization of spring steel for automobile stabilizer bars

Abstract

The application discloses a heating control method for reducing decarburization of spring steel for automobile stabilizer bars, and comprises the following steps: 1) by loading steel steps in the furnace, the total heating time of the blank in the heating furnace is controlled to be 180min-250min; and 2) the heating second-stage temperature is controlled to be 950 DEG C-1060 DEG C, and the soaking temperature is controlled to be 1060 DEG C-1120 DEG C. By controlling the blank quantity in the furnace, shortening the heating time and reducing the heating temperature, the surface decarburization of the spring steel can be reduced to even zero decarburization, so that the production cost is reduced, and the delivery rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to spring steel, especially to a heating control method for reducing decarburization of spring steel for automobile stabilizer bar. BACKGROUND

[0002] At present, spring steel is used more and more widely in various fields in China. Spring steel has high elastic limit and bearing capacity, plays a role of buffering and shock absorption, and has particularly high requirement on fatigue performance. Surface decarburization has great damage to the fatigue performance of spring, especially for some precision spring products such as spring steel for automobile stabilizer bar. The surface is not allowed to have full decarburization layer, and the raw material is zero decarburization delivery. In Nanjing Steel Medium Bar Plant, since the total length of the heating furnace is 42.6 meters, the billet is 250mm*300mm*11000mm, and the production rhythm of small-sized spring steel is slower, generally more than 5 hours of heating in the furnace, the surface decarburization layer of the finished product is thicker, and the surface peeling is usually needed to realize zero decarburization delivery. The billet surface peeling or billet surface paint brushing is usually used to reduce decarburization in production, which not only increases the production cost, but also causes certain influence on the environment. SUMMARY

[0003] The present application provides a heating control method for reducing decarburization of spring steel for automobile stabilizer bar, which can reduce the surface decarburization of spring steel and even achieve zero decarburization by controlling the number of billets in the furnace, shortening the heating time and reducing the heating temperature, thereby reducing the production cost and improving the delivery rate.

[0004] Technical scheme: The heating control method for reducing decarburization of spring steel for automobile stabilizer bar provided by the present application has the characteristics that it comprises the following steps: 1) controlling the total heating time of the billet in the heating furnace to be 180min-250min by means of furnace steel empty steps; and 2) controlling the heating second-stage temperature to be 950℃-1060℃ and the soaking temperature to be 1060℃-1120℃.

[0005] In the step 1) furnace steel empty steps, for Φ16mm, the steel tapping rhythm is greater than 254s, the steel empty steps require that 1 empty is loaded for 3, and the machine-hour output is less than or equal to 84 tons / h.

[0006] In the step 1) furnace steel empty steps, for Φ17mm-22mm, the steel tapping rhythm is 196s-254s, the steel empty steps require that 1 empty is loaded for 2, and the machine-hour output is 85 tons / h-109 tons / h.

[0007] In the step 1) furnace steel empty steps, for Φ23mm-30mm, the steel tapping rhythm is 144s-196s, the steel empty steps require that 1 empty is loaded for 2, and the machine-hour output is 110 tons / h-150 tons / h.

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

[0009] The preheating time is 60 min, the heating time is 60 min-90 min, and the soaking time is 60 min.

[0010] The preheating temperature is ≤800℃.

[0011] 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] The temperature of the first heating section is ≤950℃, and the temperature of the second heating section is 950℃-1050℃.

[0013] The temperature of the first soaking section is 1060℃-1120℃, and the temperature of the second soaking section is 1080℃-1120℃.

[0014] Compared with the prior art, the present application has the following advantages: the present application reduces the surface decarburization of the Φ16mm-30mm bar grade 55Cr3, SUP9D spring steel for automobile stabilizer bars; the total decarburized layer of the spring steel is controlled to be 0.08mm-0.15mm; and the surface full decarburized layer of the spring steel is 0. The present application can reduce the surface decarburization of the spring steel even to zero decarburization by controlling the quantity of the billets in the furnace, reducing the heating time and the heating temperature, thereby reducing the production cost and improving the delivery rate. DETAILED DESCRIPTION

[0015] The technical solutions of the present application will be further described in combination with the specific embodiments.

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

[0017] 1) The total heating time of the billets in the heating furnace is controlled to be 180min-250min by the steel loading empty steps in the furnace. In the steel loading empty steps in the furnace, for Φ16mm, the steel tapping rhythm is >254s, the steel loading empty step requirement is 1 empty 3, and the machine hourly output is ≤84 tons / h; for Φ17mm-22mm, the steel tapping rhythm is 196s-254s, the steel loading empty step requirement is 1 empty 2, and the machine hourly output is 85 tons / h-109 tons / h; for Φ23mm-30mm, the steel tapping rhythm is 144s-196s, the steel loading empty step requirement is 1 empty 2, and the machine hourly output is 110 tons / h-150 tons / h.

[0018]

[0019] By controlling the steel loading empty step, the preheating time in the heating furnace is controlled at 60 min, the heating time is controlled at 60-90 min, and the soaking time is controlled at about 60 min, so that the time of the blank in the high temperature section is reduced, the reaction of the carbon atoms on the surface of the blank with the oxygen atoms in the furnace gas at high temperature is effectively avoided, the surface decarburization of the finished product is reduced, and the production efficiency is not affected.

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

[0021]

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

[0023] The chemical composition of the spring steel is: 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%, and the balance of Fe.

[0024] The present application shortens the heating time of the blank in the furnace by controlling the steel loading empty step, reduces the heating temperature, ensures the uniformity of the blank temperature, reduces the oxidation reaction of the carbon atoms on the surface of the blank with the oxygen atoms in the furnace gas, controls the total decarburization layer thickness of the product surface at 0.08mm-0.15mm, and the full decarburization layer is 0, improves the fatigue strength of the spring steel, reduces the surface decarburization layer of the spring steel, and the full decarburization layer is 0, not only reduces the production cost, but also improves the delivery speed. It has high use value.

Claims

1. A heating control method for reducing decarburization of a spring steel for a stabilizer bar of an automobile, characterized by: The method comprises the following steps: 1) controlling the total heating time of the blank in the heating furnace to 180-250 min by means of furnace emptying; 2) controlling the second heating temperature to 950-1060℃ and the soaking temperature to 1060-1120℃; the spring steel comprises the following components in percentage by mass: 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%, and the balance of Fe; In the step 1), the furnace emptying is performed at a tapping rhythm of >254 s for Φ16 mm, and the emptying step requires emptying 1 and charging 3, and the machine-hour output is ≤84 tons / h; for Φ17-22 mm, the tapping rhythm is 196-254 s, the emptying step requires emptying 1 and charging 2, and the machine-hour output is 85-109 tons / h; for Φ23-30 mm, the tapping rhythm is 144-196 s, the emptying step requires emptying 1 and charging 2, and the machine-hour output is 110-150 tons / h. The total heating time in the step 1) comprises the preheating time, the heating time and the soaking time; the preheating temperature is ≤800℃.

2. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 1, characterized by: The preheating time is 60 min, the heating time is 60-90 min, and the soaking time is 60 min.

3. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 1, characterized by: The heating section comprises a first heating section and a second heating section, and the soaking section comprises a first soaking section and a second soaking section.

4. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 3, characterized by: The first heating section has a temperature of ≤950℃, and the second heating section has a temperature of 950-1050℃.

5. The heating control method for reducing decarburization of spring steel for automobile stabilizer bars according to claim 3, characterized by: The first soaking section has a temperature of 1060-1120℃, and the second soaking section has a temperature of 1080-1120℃.

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