CN113523911B

CN113523911B - Method for solving cracks of 10Cr17 steel grade head and tail blanks

Info

Publication number: CN113523911B
Application number: CN202110848529.9A
Authority: CN
Inventors: 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
Original assignee: Shandong Taishan Steel Group
Current assignee: Shandong Taishan Steel Group
Priority date: 2021-07-27
Filing date: 2021-07-27
Publication date: 2023-08-25
Anticipated expiration: 2041-07-27
Also published as: CN113523911A

Abstract

The application discloses a method for solving the problem of cracks of a head blank and a tail blank of a 10Cr17 steel grade, which comprises the following steps: maintaining the temperature of the head and tail blanks of the 10Cr17 steel grade at 200-400 ℃, and sequentially carrying out rough grinding and fine grinding on the surfaces of the head and tail blanks 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. During fine grinding, the current of the grinding machine is 120-200A. The method solves the problem that the surface of the 10Cr17 head and tail blank locally generates crack defects, the peeling phenomenon of the surface of the Du Juehou continuous hot rolled steel coil is obviously improved, and the acid washing first-stage product rate is obviously improved, so that the product quality is improved, and the economic benefit is greatly improved. The method of the application can also reduce the grinding times and the grinding rate, avoid the occurrence of cracks on the head and tail blanks and reduce the cost of products.

Description

Method for solving cracks of 10Cr17 steel grade head and tail blanks

Technical Field

The application relates to the technical field of metallurgy, in particular to a method for solving the cracking of a head and tail blank of a 10Cr17 steel grade.

Background

The 10Cr17 steel has wide application range, and the stainless steel has strong corrosion resistance and good formability. However, when the production of the 10Cr17 steel grade is just started and the production is finished, the control of the production process is unstable, the starting pulling speed is low, the cooling strength is low in the casting process, and the obtained head and tail billets are easy to have defects. For example, the head and tail blanks are easy to have defects such as cracks and the like in the grinding process; the defects of peeling, cracking and the like of the steel belt easily occur after rolling and acid washing, thereby reducing the yield of head and tail blanks.

The 10Cr17 steel type has more cracks, such as vanadium addition amount, continuous casting equipment precision, tundish temperature, primary and secondary cooling strength, driving roller pressure and the like, but the internal cracks and the healing of the cracks of the stainless steel are generally affected, and the problems can be solved by adjusting the formula and the process. In actual production, even if the adjustment is made, the surface of the head blank and the tail blank inevitably have defects such as cracks and chaps; or the surfaces of the head and tail blanks are not defective, 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 yield of the head and tail blanks, and influence the use of the head and tail blanks. Therefore, a method is needed to avoid cracks on the surfaces of the head and tail billets of the 10Cr17 steel grade, avoid defects in the subsequent hot rolling and pickling processes, and improve the yield of the head and tail billets of the 10Cr17 steel grade.

Disclosure of Invention

Aiming at the prior art, the application aims to provide a method for solving the cracking of the head and tail blanks of the 10Cr17 steel grade. The application can avoid cracks on the surfaces of the head and tail blanks of the 10Cr17 steel, avoid defects in the subsequent pickling process and improve the yield of the head and tail blanks of the 10Cr17 steel.

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

the application provides a method for solving the problem of cracks of a head and tail blank of a 10Cr17 steel grade, which comprises the following steps:

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

Preferably, before grinding the head and tail blanks of the 10Cr17 steel grade, heating the heat preservation pit to 300-400 ℃, putting the head and tail blanks to be ground into the heat preservation pit, sealing the heat preservation pit, and lifting the head and tail blanks of the 10Cr17 steel grade from the heat preservation pit during grinding.

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

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

Preferably, in rough grinding, the grinding wheel of the sharpening machine is a 16-mesh grinding wheel.

Preferably, the surface roughness of the head and tail blanks is smaller than 0.5mm, and the finish of the finish grinding.

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

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

The application has the beneficial effects that:

(1) The method solves the problem that the surface of the 10Cr17 head and tail blank is locally heated to generate crack defects, the surface peeling phenomenon of Du Juehou continuous hot rolled steel coils is obviously improved, and the acid washing first-stage product rate is obviously improved, so that the product quality is improved, and the economic benefit is greatly improved.

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

Detailed Description

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the application. 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 art section, in the existing steel types, the main martensitic steel which needs to be ground at a temperature is mainly martensitic steel with the carbon content of 0.20-0.40 percent; the steel grade with low carbon content is generally ground at normal temperature. The actual carbon content of the 10Cr17 steel grade is only 0.04-0.06%, the head and tail blanks are generally required to be polished at normal temperature due to unstable production process, the defects of cracks, peeling and the like in subsequent processing are avoided, but the pickling first-stage product rate of the head and tail blanks polished at normal temperature is only 60-70%.

Based on this, the application aims to provide a method for solving the cracking of the head and tail blanks of the 10Cr17 steel grade. Experiments show that the product quality can be improved by grinding the 10Cr17 steel at 200-400 ℃. Further research shows that different currents are set in the grinding process to generate different pressures, the heat generated by grinding the steel under different pressures is also different, and the change of the heat conductivity coefficient influences the release of stress due to the fact that the heat conductivity coefficient of the steel is different at different temperatures, so that the generation of cracks is influenced. By the rough grinding with higher pressure and the fine grinding with lower pressure, the grinding rate can be reduced and cracks of the head and tail blanks can be further avoided. The method of the application can reduce the grinding times, reduce the grinding rate, avoid cracks of the head and tail blanks and reduce the cost of products.

In order to enable those skilled in the art to more clearly understand the technical scheme of the present application, the technical scheme of the present application will be described in detail with reference to specific embodiments.

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

Example 1

Step one: dephosphorization process: molten iron P: 0.075-0.150%, dephosphorizing by lime powder and dephosphorizing agent, removing slag cleanly after dephosphorizing, and after pretreatment, keeping the P of semisteel less than 0.020%;

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

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

step four: continuous casting process: the continuous casting process adopts whole-process protection casting, 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 water quantity on the wide side of a crystallizer is: 2600-4000L/min, narrow side water content: 400-600L/min, electromagnetic stirring parameters: current 200-300A, frequency: 4.0 to 6.0HZ; the offline temperature of the red blank is more than or equal to 600 ℃;

step five: and (3) polishing: maintaining the temperature of the head and tail blanks of the 10Cr17 steel grade at 200-400 ℃, firstly, carrying out rough grinding on the surfaces of the head and tail blanks by using a grinding machine, and carrying out grinding for 2 times by using a grinding machine with a 16-mesh grinding wheel, wherein the current is 300A, and the grinding feed is 30mm; and (3) carrying out fine grinding after rough grinding is finished, using a grinding wheel of a replacement 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 ℃, feeding the head and tail blanks into a heat preservation pit, heating to 300-400 ℃, taking out, and continuously grinding.

Examples 2 to 3 and comparative examples 1 to 8

The polishing methods of examples 2 to 3 and comparative examples 1 to 8 were the same as example 1, except that the polishing temperature, the polishing machine current, and the number of polishing times were specifically shown in table 1.

TABLE 1

In the polishing processes of examples 1 to 3 and comparative examples 1 to 8, the polishing rates of the head and tail blanks after polishing are counted; hot rolling and pickling the polished head and tail blanks, and calculating the first grade product rate; the results obtained are shown in Table 2.

TABLE 2

Project	Grinding rate%	First grade rate%
			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 is clear from Table 2, the polishing rates of the head and tail billets polished in examples 1 to 3 were low, and the cost of the billets could be reduced. The first grade product rate also reaches 100 percent. Whereas comparative examples 1 to 8 were polished with the head and tail blanks having the polishing rates higher than examples 1 to 3 and the first-stage product rates lower than examples 1 to 3.

As can be seen from the combination of the table 1, the method of the application can reduce the number of times of grinding, reduce the grinding rate, avoid cracks on the head and tail blanks, and greatly reduce the cost of products.

The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. Use of a method for solving cracks of a 10Cr17 steel grade head and tail blank in improving the pickling first grade rate, the method comprising:

maintaining the temperature of the head and tail blanks of the 10Cr17 steel grade at 200-400 ℃, and sequentially carrying out rough grinding and fine grinding on the surfaces of the head and tail blanks by using a grinding machine; the number of times of rough grinding is 1-3, the current of a sharpening machine is 250-350A during rough grinding, the grinding wheel of the sharpening machine is a 16-mesh grinding wheel during rough grinding, and the finish of fine grinding is finished until the surface roughness of a head blank and a tail blank is less than 0.5 mm; the current of the sharpening machine is 120-200A during fine grinding, and the grinding wheel of the sharpening machine is a 30-mesh grinding wheel during fine grinding; stopping grinding when the temperature of the head and tail blanks is lower than 150 ℃;

before grinding the head and tail blanks of the 10Cr17 steel types, heating the heat preservation pit to 300-400 ℃, putting the head and tail blanks to be ground into the heat preservation pit, sealing the heat preservation pit, and lifting the head and tail blanks of the 10Cr17 steel types from the heat preservation pit during grinding.