阅读说明：本技术 一种解决10Cr17钢种头尾坯裂纹的方法 (Method for solving 10Cr17 steel head and tail billet cracks ) 是由 赵刚 亓欣华 焦玉水 吴荣刚 殷齐敏 乔春刚 王福河 朱坤亮 邵书明 柴坤军 于 2021-07-27 设计创作，主要内容包括：本发明公开了一种解决10Cr17钢种头尾坯裂纹的方法,所述方法为：保持10Cr17钢种头尾坯的温度为200～400℃,使用修磨机对头尾坯的表面依次进行粗磨和精磨；当头尾坯的温度低于150℃时,停止修磨。粗磨时,修磨机的电流为250～350A。精磨时,修磨机的电流为120～200A。本发明解决了10Cr17头尾坯表面局部产生裂纹缺陷的问题,杜绝后续热轧钢卷表面起皮现象,酸洗一级品率显著提高,从而提升了产品质量,大幅度提高经济效益。本发明的方法还可降低修磨次数和修磨率,避免了头尾坯出现裂纹,降低产品的成本。(The invention discloses a method for solving 10Cr17 steel head and tail billet cracks, which comprises the following steps: keeping the temperature of the 10Cr17 steel head and tail blank at 200-400 ℃, and sequentially carrying out coarse grinding and fine grinding on the surface of the head and tail blank by using a grinding machine; and stopping grinding when the temperature of the head and tail blanks is lower than 150 ℃. During coarse grinding, the current of the grinding machine is 250-350A. And during fine grinding, the current of the sharpening machine is 120-200A. The method solves the problem that the surface of the 10Cr17 head and tail billets locally generate cracks, avoids the surface peeling phenomenon of the subsequent hot rolled steel coils, and obviously improves the first-grade product rate of pickling, thereby improving the product quality and greatly improving the economic benefit. The method of the invention can also reduce the grinding times and the grinding rate, avoid the cracks of the head and tail blanks and reduce the cost of products.)

1. A method for solving the problem of cracks of head and tail blanks of 10Cr17 steel is characterized by comprising the following steps:

keeping the temperature of the 10Cr17 steel head and tail blank at 200-400 ℃, and sequentially carrying out coarse grinding and fine grinding on the surface of the head and tail blank by using a grinding machine; and stopping grinding when the temperature of the head and tail blanks is lower than 150 ℃.

2. The method according to claim 1, wherein before the 10Cr17 steel grade head and tail blank is polished, the temperature of a heat preservation pit is raised to 300-400 ℃, the head and tail blank to be polished is placed into the heat preservation pit, the heat preservation pit is sealed, and the 10Cr17 steel grade head and tail blank is hoisted from the heat preservation pit during polishing.

3. The method according to claim 1, wherein the number of rough grinding is 1 to 3.

4. The method according to claim 1, wherein the current of the sharpening machine is 250-350A during rough grinding.

5. The method according to claim 1, wherein the grinding wheel of the sharpening machine is a 16-mesh grinding wheel during the rough grinding.

6. The method of claim 1, wherein the refining is completed until the surface roughness of the head and tail billets is less than 0.5 mm.

7. The method according to claim 1, wherein the sharpening machine has a current of 120 to 200A in the refining.

8. The method according to claim 1, wherein the grinding wheel of the sharpening machine is a 30-mesh grinding wheel in the fine grinding.

Technical Field

The invention relates to the technical field of metallurgy, in particular to a method for solving 10Cr17 steel head and tail billet cracks.

Background

The 10Cr17 steel has wide application, strong corrosion resistance and good formability. However, when the 10Cr17 steel is produced at the beginning and at the end, the production process is not stably controlled, the casting speed is low in the casting process, and the cooling strength is high, so that the obtained head and tail blanks are easy to have defects. For example, the head and tail blanks are easy to have cracks, crazing and other defects in the coping process; after rolling and acid pickling, the defects of peeling, cracks and the like of the steel strip are easy to occur, so that the yield of the head and tail blanks is reduced.

The 10Cr17 steel has more cracks, such as the addition amount of vanadium, the precision of continuous casting equipment, the temperature of a tundish, the strength of primary and secondary cooling, the pressure of a driving roller and the like, but the internal cracks and the healing of the cracks which generally affect the stainless steel can be solved by adjusting the formula and the process. In actual production, even if the adjustment is carried out, the surface of the head and tail blank inevitably has defects such as cracks, chaps and the like; or the surface of the head and tail billets has no defects, but the problems of peeling, cracking and the like of the steel strip can occur in the subsequent hot rolling and pickling processes. These all reduce the lumber recovery of head-tail base, influence the use of head-tail base. Therefore, a method is needed for avoiding the cracks on the surface of the 10Cr17 steel grade head and tail billet, enabling the cracks not to appear in the subsequent hot rolling and pickling processes and improving the yield of the 10Cr17 steel grade head and tail billet.

Disclosure of Invention

In view of the prior art, the invention aims to provide a method for solving the problem of cracking of 10Cr17 steel head and tail billets. The method can avoid the cracks on the surface of the head and tail billet of the 10Cr17 steel grade, ensure that the surface of the head and tail billet of the 10Cr17 steel grade does not have defects in the subsequent pickling process, and improve the yield of the head and tail billet of the 10Cr17 steel grade.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for solving 10Cr17 steel head and tail billet cracks, which comprises the following steps:

keeping the temperature of the 10Cr17 steel head and tail blank at 200-400 ℃, and sequentially carrying out coarse grinding and fine grinding on the surface of the head and tail blank by using a grinding machine; and stopping grinding when the temperature of the head and tail blanks is lower than 150 ℃.

Preferably, before the 10Cr17 steel grade head and tail blank is polished, the temperature of the heat preservation pit is raised to 300-400 ℃, the head and tail blank to be polished is placed into the heat preservation pit, the heat preservation pit is sealed, and the 10Cr17 steel grade head and tail blank is hoisted from the heat preservation pit during polishing.

Preferably, the number of times of rough grinding is 1 to 3.

Preferably, the current of the sharpening machine is 250-350A during coarse grinding.

Preferably, during coarse grinding, the grinding wheel of the sharpening machine is a 16-mesh grinding wheel.

Preferably, the refining is carried out until the surface roughness of the head and tail billets is less than 0.5mm, and the refining is finished.

Preferably, the current of the sharpening machine is 120-200A during the fine grinding.

Preferably, the grinding wheel of the sharpening machine is a 30-mesh grinding wheel during fine grinding.

The invention has the beneficial effects that:

(1) the invention solves the problem that the surface of the 10Cr17 head and tail billets is locally heated to generate crack defects, eliminates the surface peeling phenomenon of the subsequent hot rolled steel coils, and obviously improves the primary product rate of pickling, thereby improving the product quality and greatly improving the economic benefit.

(2) The method of the invention can also reduce the grinding times and the grinding rate, avoid the cracks of the head and tail blanks and reduce the cost of products.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

As described in the background section, the existing steel grades need temperature thinning and are mainly martensitic steel, and the carbon content is 0.20-0.40% before; the steel grade with low carbon content is generally ground at normal temperature. The actual carbon content of the 10Cr17 steel is only 0.04-0.06%, the head and tail blanks generally need normal-temperature grinding due to the unstable production process, the defects of cracks, peeling and the like in subsequent processing are avoided, and the primary yield of the head and tail blanks subjected to normal-temperature grinding is only 60-70%.

Based on the above, the invention aims to provide a method for solving the head and tail billet cracks of the 10Cr17 steel grade. According to the invention, tests show that the product quality can be improved by carrying out coping when the temperature of the 10Cr17 steel is kept at 200-400 ℃. Further research shows that different pressures are generated by setting different currents in the grinding process, heat generated by grinding under different pressures is different, and the change of the heat conductivity coefficient influences the release of stress due to the fact that the heat conductivity coefficient of steel is different under different temperatures, so that the generation of cracks is influenced. Through the coarse grinding under higher pressure and the fine grinding under lower pressure, the grinding rate can be reduced, and cracks of head and tail blanks can be further avoided. The method can reduce the grinding times, reduce the grinding rate, avoid the cracks of the head and tail blanks and reduce the cost of products.

In order to make the technical solutions of the present application more clearly understood by those skilled in the art, the technical solutions of the present application will be described in detail below with reference to specific embodiments.

The test materials used in the examples of the present invention are all conventional in the art and commercially available.

Example 1

The method comprises the following steps: a dephosphorization process: molten iron P: 0.075-0.150% of the steel, dephosphorizing by using lime powder and a dephosphorizing agent, and deslagging to be clean after dephosphorizing, wherein after pretreatment, the P content of the semisteel is less than 0.020%;

step two: the smelting process of the TSR furnace comprises the following steps: the addition amount of high-carbon ferrochrome is 20-30%, P of the dephosphorized semisteel is less than 0.020%, the temperature of the dephosphorized molten iron is 1300-1450 ℃, the blowing end point temperature is controlled at 1700-1740 ℃, and C: 0.01-0.08%, the reduction time is more than 6 minutes, and the Cr: 16.0-17.5 percent of ferrosilicon is added in an amount of 1-1.5 percent for reduction, the color of the reduced slag is controlled to be white slag, a secondary desulfurization process is adopted, the content of the tapping sulfur is strictly controlled, and the content of the tapping sulfur is less than or equal to 0.006 percent;

step three: an LF refining procedure: after the molten steel reaches LF, the thickness of a slag layer in a ladle is 150-300 mm, the station entering temperature is 1500-1620 ℃, the refining time is 45-120 min, the power transmission time is 15-40 min, lime and fluorite are added to adjust the refining alkalinity R to be more than 2.0, the soft blowing time and the calming time are more than or equal to 15 min, and the station leaving temperature is 1560-1585 ℃;

step four: and (3) continuous casting process: the continuous casting process adopts whole-process protective pouring, the superheat degree is controlled to be 20 +/-5 ℃, the drawing speed is 1.0-1.1 m/min, the thickness of a continuous casting blank is 200mm, the width is 1000-1600 mm, and the amount of water on the wide side of a crystallizer is as follows: 2600-4000L/min, narrow water amount: 400-600L/min, electromagnetic stirring parameters: current 200-300A, frequency: 4.0-6.0 HZ; the offline temperature of the red blank is more than or equal to 600 ℃;

step five: a coping process: keeping the temperature of a 10Cr17 steel head-tail blank at 200-400 ℃, firstly carrying out coarse grinding on the surface of the head-tail blank by using a grinding machine, carrying out grinding for 2 times by using a 16-mesh grinding wheel with the current of 300A, and carrying out grinding feeding with the feed amount of 30 mm; and (3) performing accurate grinding after the coarse grinding is finished, using a grinding wheel of a grinding machine, using a 30-mesh grinding wheel, adjusting the current of the grinding machine to 170A, grinding once, and finishing the grinding, wherein the surface roughness of the head and tail blanks is 0.46 mm.

Stopping grinding when the temperature of the head and tail blanks is lower than 150 ℃, heating the head and tail blanks to 300-400 ℃ in a heat preservation pit, and taking out the head and tail blanks to continue grinding.

Examples 2 to 3 and comparative examples 1 to 8

The grinding methods of examples 2 to 3 and comparative examples 1 to 8 are the same as example 1, and the differences are grinding temperature, grinder current and grinding times, which are specifically shown in table 1.

TABLE 1

In the grinding processes of the embodiments 1-3 and the comparative examples 1-8, the grinding rate of the head and tail blanks after grinding is counted; carrying out hot rolling and acid pickling on the head and tail blanks subjected to polishing, and calculating the first-grade product rate; the results are shown in Table 2.

TABLE 2

Item	Percent grinding rate%	The first grade rate of finished products%
			Example 1	2.6	100
Example 2	2.8	100
			Example 3	2.7	100
Comparative example 1	4.3	73
			Comparative example 2	4.8	66
Comparative example 3	4.3	96
			Comparative example 4	4.2	94
Comparative example 5	4.2	90
			Comparative example 6	4.0	94
Comparative example 7	4.2	90
			Comparative example 8	4.2	93

As can be seen from table 2, the head and tail billets polished in examples 1 to 3 had a low polishing rate, and the cost of the billet could be reduced. The first-grade product rate also reaches 100 percent. The grinding rate of the head and tail blanks ground in the comparative examples 1-8 is higher than that of the examples 1-3, and the first-grade product rate is lower than that of the examples 1-3.

As can be seen from the table 1, the method of the invention can reduce the grinding times, reduce the grinding rate, avoid the cracks of the head and tail blanks and greatly reduce the cost of the product.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.