阅读说明：本技术 一种辊套用32Cr3Mo1V连铸大圆坯生产方法 (Production method of 32Cr3Mo1V continuous casting round billet for roll sleeve ) 是由 许民 徐书城 单文瑞 陈远清 汪德伟 陈树军 轩康乐 柏京波 于 2019-09-28 设计创作，主要内容包括：本发明涉及连铸大圆坯生产技术领域,具体公开了一种辊套用32Cr3Mo1V连铸大圆坯生产方法。主要解决了现有技术中存在的连铸大圆坯,尤其是大断面存在中心缺陷较大,不能用于生产32Cr3Mo1V辊套主要的原坯料的技术问题。本发明一种辊套用32Cr3Mo1V连铸大圆坯生产方法,其中,包括：钢水冶炼,所述钢水冶炼采用杂质元素含量低的铁水,所述杂质元素含量为：pb≤0.002％,As≤0.01％,Sn≤0.002％,Sb≤0.003％,Bi≤0.002％；连铸,所述连铸全程采用保护浇铸,恒拉速生产,使用结晶器、铸流、末端电磁搅拌,配合弱二冷水；加热、锻压,采取低温装炉、加热、镦粗、冲孔、拔长、扩孔,生产的连铸圆坯的化学成分合格、低倍质量及中心质量满足锻造辊套的要求,可用于代替钢锭生产32Cr3Mo1V辊套,具有较好的发展前景。(The invention relates to the technical field of continuous casting large round billet production, and particularly discloses a method for producing a 32Cr3Mo1V continuous casting large round billet for a roll sleeve. Mainly solves the technical problems that the continuous casting large round billet in the prior art, especially the large section has larger central defect and can not be used for producing the main raw billet of the 32Cr3Mo1V roller sleeve. The invention relates to a method for producing a 32Cr3Mo1V continuous casting round billet for a roll sleeve, which comprises the following steps: smelting molten steel, wherein the molten steel smelting adopts molten iron with low impurity element content, and the impurity element content is as follows: pb is less than or equal to 0.002 percent, As is less than or equal to 0.01 percent, Sn is less than or equal to 0.002 percent, Sb is less than or equal to 0.003 percent, and Bi is less than or equal to 0.002 percent; continuous casting, wherein the whole continuous casting process adopts protective casting and constant-pulling-speed production, a crystallizer, a casting flow and tail end electromagnetic stirring are used, and weak secondary cooling water is matched; heating and forging, adopting low-temperature furnace charging, heating, upsetting, punching, drawing out and reaming, wherein the chemical components of the produced continuous casting round billet are qualified, the macroscopic quality and the central quality meet the requirements of forging the roller sleeve, and the continuous casting round billet can be used for replacing steel ingots to produce 32Cr3Mo1V roller sleeves and has better development prospect.)

1. A method for producing a 32Cr3Mo1V continuous casting round billet for a roll sleeve, which comprises the following steps:

smelting molten steel, wherein the molten steel smelting adopts molten iron with low impurity element content, and the impurity element content is as follows: pb is less than or equal to 0.002 percent, As is less than or equal to 0.01 percent, Sn is less than or equal to 0.002 percent, Sb is less than or equal to 0.003 percent, and Bi is less than or equal to 0.002 percent;

continuous casting, wherein the whole process of the continuous casting adopts protective casting, the continuous casting adopts constant drawing speed production, a crystallizer, a casting flow and tail end electromagnetic stirring are used, and weak secondary cooling water is matched;

heating, forging, charging at low temperature, heating, upsetting, punching, drawing out and reaming.

2. The method for producing the continuous casting round billet for the roll sleeve of 32Cr3Mo1V as claimed in claim 1, wherein in the molten steel smelting process:

and sequentially carrying out electric arc furnace smelting, LF refining and VD vacuum degassing treatment on the molten iron.

3. The method for producing a continuous casting large round billet for a roll sleeve 32Cr3Mo1V as claimed in claim 1, wherein in the continuous casting process:

placing the 32Cr3Mo1V continuous casting billet into a hot charging trolley furnace for annealing at the high temperature of more than or equal to 550 ℃.

4. The method for producing a continuous casting round billet for a roll sleeve of 32Cr3Mo1V as claimed in claim 3, wherein the continuous casting specification of 32Cr3Mo1V is a Φ 700mm specification.

5. The method for producing a continuous casting large round billet for a roll sleeve 32Cr3Mo1V as claimed in claim 3, wherein in the continuous casting process:

the annealing temperature in the annealing process is 850-900 ℃.

6. The method for producing a continuous cast round billet for a roll shell of 32Cr3Mo1V according to claim 5, wherein,

in the casting process, the annealing temperature and the heat preservation time are more than or equal to 24 hours.

7. The method for producing a continuous casting large round billet for a roll sleeve 32Cr3Mo1V as claimed in claim 1, wherein in the continuous casting process:

in the constant-pulling-speed production process, the superheat degree is controlled to be stabilized between 18 and 30 ℃.

8. The method for producing a continuous cast round billet for a roll shell of 32Cr3Mo1V according to claim 7, wherein,

further controlling the superheat degree to be stable between 20 and 25 ℃.

9. The method for producing a continuous casting large round billet for a roll sleeve 32Cr3Mo1V as claimed in claim 1, wherein in the continuous casting process:

and after the casting is finished, cooling the continuous casting large round billet to below 150 ℃ along with the furnace, discharging, and entering the next step.

10. The method for producing a continuous cast round billet for a roll sleeve of 32Cr3Mo1V as claimed in claim 1,

in the heating and forging process, the heating and forging environment temperature is less than or equal to 450 ℃.

11. The method for producing the continuous casting round billet for the roll sleeve of 32Cr3Mo1V as claimed in claim 1, wherein the punching operation is performed by a numerical control lathe, and the hole expanding operation is performed by a numerical control lathe.

Technical Field

The invention relates to the technical field of continuous casting large round billet production, in particular to a method for producing a 32Cr3Mo1V continuous casting large round billet for a roller sleeve.

Background

32Cr3Mo1V is a major material for roller covers in the industrial field of aluminum strip rolling because of its high thermal fatigue resistance, good thermal conductivity and excellent mechanical properties.

At present, the main raw blank for producing the 32Cr3Mo1V roller sleeve is a die-cast steel ingot, and a continuous casting large round billet is not used, because the center quality of the steel ingot is superior to that of the continuous casting large round billet, and the steel ingot is forged and subjected to subsequent heat treatment to obtain a roller sleeve product meeting the performance requirements. However, compared with the continuous casting large round billet, the yield of the die-cast steel ingot is lower than that of the continuous casting large round billet, a roller sleeve with the same size is forged, the yield of the steel ingot is only 81.5%, the yield of the continuous casting large round billet is about 92.7%, the molten steel yield of the die-cast steel ingot is lower than that of the continuous casting large round billet, the automation degree of die casting production is far lower than that of the continuous casting production, the energy consumption in the die casting production process is higher than that of the continuous casting, the die casting production cost is higher, specifically, the continuous casting is more than 3 furnaces, and the die casting production cost is about 150 yuan/t higher than that of the continuous casting.

Because the casting mode and the solidification principle of continuous casting and die casting are different, the continuous casting large round billet, especially the large section has the characteristics of large central defect and the like, and can not be used for producing the main raw billet of the 32Cr3Mo1V roller sleeve, therefore, the reasonable continuous casting process is adopted, the internal quality of the continuous casting billet is improved, and the 32Cr3Mo1V roller sleeve produced by using the continuous casting large round billet instead of a steel ingot has better development prospect.

Disclosure of Invention

The invention aims to provide a method for producing a 32Cr3Mo1V continuous casting large round billet for a roller sleeve, which aims to overcome the technical problems that the continuous casting large round billet, particularly a large section has large central defect and cannot be used for producing a main raw billet of the 32Cr3Mo1V roller sleeve, so as to improve the internal quality of a continuous casting billet and further produce the continuous casting large round billet capable of replacing a steel ingot to forge the 32Cr3Mo1V roller sleeve.

In order to achieve one of the purposes, the invention adopts the following technical scheme:

a method for producing a 32Cr3Mo1V continuous casting round billet for a roll sleeve, which comprises the following steps:

smelting molten steel, wherein the molten steel smelting adopts molten iron with low impurity element content, and the impurity element content is as follows: pb is less than or equal to 0.002 percent, As is less than or equal to 0.01 percent, Sn is less than or equal to 0.002 percent, Sb is less than or equal to 0.003 percent, and Bi is less than or equal to 0.002 percent;

continuous casting, wherein the whole continuous casting process adopts protective casting and constant-pulling-speed production, a crystallizer, a casting flow and tail end electromagnetic stirring are used, and weak secondary cooling water is matched, wherein the specific water amount of the secondary cooling water is controlled within the range of 0.07-0.10L/kg;

heating, forging, charging at low temperature, heating, upsetting, punching, drawing out and reaming.

By adopting the technical means, the production method of the 32Cr3Mo1V continuous casting round billet for the roller sleeve is carried out by an electric furnace → LF refining → VD vacuum degassing → Phi 700mm continuous casting → annealing, so that the production automation degree is increased, the energy consumption is low, and the production cost is effectively reduced; the continuous casting adopts constant drawing speed, controls the superheat degree to be stable, adopts a crystallizer, a casting flow and tail end electromagnetic stirring, protects the casting in the whole process, produces 32Cr3Mo1V continuous casting round billets, has no riser or nozzle, reduces the procedures of forging and cutting the riser or nozzle, improves the internal quality of the continuous casting billets, reduces the component segregation of molten steel in the solidification process, reduces the central cracks and shrinkage cavities of the continuous casting billets, meets the requirements of forging roller sleeves on low-power quality and central quality, produces the continuous casting round billets by replacing the continuous casting round billets produced by the process of the invention to produce 32Cr3Mo1V roller sleeves, has basically consistent segregation in the length direction, avoids the serious defects caused by A-type segregation which is segregated upwards in the longitudinal direction and V-type segregation which is downwards in the longitudinal direction, and prolongs the service life of the roller sleeves.

According to one embodiment of the invention, in the molten steel smelting process: and sequentially carrying out electric arc furnace smelting, LF refining and VD vacuum degassing treatment on the molten iron. By adopting the technical means, harmful elements in the molten iron are controlled, the 32Cr3Mo1V steel with low gas content, low P content and low S content is produced, and the chemical components of the molten steel meet the standard requirements.

According to an embodiment of the invention, wherein during the continuous casting: placing the 32Cr3Mo1V continuous casting billet into a hot charging trolley furnace for annealing at the temperature of more than or equal to 550 ℃.

According to one embodiment of the invention, wherein the 32Cr3Mo1V continuous casting gauge is a Φ 700mm gauge.

According to an embodiment of the invention, the annealing temperature of the annealing process is 850-900 ℃. By adopting the technical means, the annealing temperature is set to 850-900 ℃, so that resources can be saved, and cracks generated during heating forging due to large central defects of continuous casting billets are prevented. If the annealing temperature is more than 900 ℃, although the central crack and crack of the continuous casting billet can be prevented, the temperature is higher, so more energy is needed, and the resource waste is serious. However, if the annealing temperature is controlled to be lower than 550 ℃, for example, the annealing temperature of 450 ℃ or 400 ℃, the produced continuous casting slab has more cracks therein, has lower quality and can not meet the requirements, and is not suitable for replacing steel ingots to produce 32Cr3Mo1V roller sleeves. Therefore, in the production process, the annealing temperature is controlled to be 850-900 ℃, so that the cracking of the continuous casting billet can be prevented, and the energy can be saved.

According to an embodiment of the invention, the annealing temperature is kept for more than or equal to 24 hours in the casting process. By adopting the technical means, the annealing temperature heat preservation time is more than or equal to 24 hours, so that enough heat preservation time is provided for molten steel, and cracks are prevented from being generated during heating forging due to large central defects of continuous casting billets.

According to an embodiment of the invention, wherein during the continuous casting: in the constant-pulling-speed production process, the superheat degree is controlled to be stable at 18-30 ℃. By adopting the technical means, the superheat degree is controlled to be stable at 18-30 ℃.

According to an embodiment of the invention, wherein the degree of superheat is further controlled to be stable between 20-25 ℃. The continuous casting superheat degree is one of key process parameters for ensuring the continuous casting yield and the casting blank quality, if the continuous casting molten steel superheat degree is too small in the production process, for example, the superheat degree is less than 15 ℃, the molten steel is easily polluted by impurities, a water gap is easily blocked and even frozen, and if the continuous casting molten steel superheat degree is too large, the central segregation of the casting blank is aggravated, and a leakage accident is even induced, or cracks occur due to the fact that a formed blank shell is thin, and columnar crystals are developed. The superheat degree of continuous casting molten steel directly influences the solidification condition of the molten steel, and further influences the surface quality of a solidified casting blank, the growth uniformity of a primary blank shell and the internal strength of the casting blank. By adopting the technical means, the superheat degree is further controlled to be stabilized between 20 and 25 ℃, so that the columnar crystal area of continuous casting is reduced, the equiaxed crystal area is enlarged, the development of columnar crystals of continuous casting is prevented, the component segregation of molten steel in the solidification process is reduced, and the internal defects of central cracks, shrinkage cavities and the like of continuous casting billets are reduced.

According to an embodiment of the invention, wherein during the continuous casting: and after the casting is finished, cooling the continuous casting round billet to below 150 ℃ along with the furnace, discharging, and entering the next step. By adopting the technical means, 80-90% of residual stress can be eliminated, the continuous casting billet has low-power quality, the center porosity is less than or equal to 1.5, the shrinkage cavity is less than or equal to 1.5, the center crack is less than or equal to 1.0, and the defects of intermediate cracks, white spots, bubbles and peeling are avoided, and the inspection and the rating are met according to a rating diagram A in the annex A of the YB/T4149 standard.

According to an embodiment of the invention, during the heating and forging process, the temperature of the heating and forging environment is less than or equal to 450 ℃. The heating and forging environmental temperature is less than or equal to 450 ℃, if the environmental temperature is more than 450 ℃ or more than 500 ℃, more energy is needed to provide the high temperature, the resource waste can be caused, the central defect of the continuous casting billet is eliminated by adopting the technical means, the forged continuous casting billet is shrunk and loosened, the product is compact, and the post-forging heat treatment process meets the flaw detection standard: JB/T5000.15-2008 II level requirement.

According to one embodiment of the invention, the punching operation is numerical control lathe punching, and the hole expanding operation is numerical control lathe punching.

The performance of the 32Cr3Mo1V continuous casting round billet for the roller sleeve finally obtained by adopting the technical means of the invention application is as follows:

(test sample specification: 10X50mmKV2, test temperature 20 ℃ C.)

The tensile strength is more than or equal to 1350 Rm/Mpa;

the specified plastic elongation strength is more than or equal to 1200 Rp0.2/Mpa;

the elongation after fracture is more than or equal to 15 percent;

the reduction of area is more than or equal to 50 percent;

the absorption energy (impact energy) is more than or equal to 30(10 multiplied by 50mmKV 2)/J.

(the impact has U-shaped notch and V-shaped notch, wherein, the test data is that the model specification is 10 multiplied by 50mmKV2 when the absorbed energy (impact energy) is more than or equal to 30/J, and the V-shaped notch.)

Test items and their corresponding standards:

the 132Cr3Mo1V steel comprises the following chemical components in percentage by weight:

C：0.33～0.36％，Mn：0.20～0.50％，Si：0.20～0.40％，Cr：3.00～3.20％，Ni：0.30～0.45％， Mo：1.00～1.20％，V：0.19～0.22％，P≤0.008％，S≤0.005％，Cu≤0.10％，Al≤0.01％，[H] ≤0.00013％，[O]≤0.0025％，[N]≤0.0075％；

2, low-power quality detection standard of continuous casting billets: rating of appendix A of the YB/T4149 standard;

3, flaw detection standard of the heat treatment process after forging: JB/T5000.15-2008.

Has the advantages that:

according to the production method of the 32Cr3Mo1V continuous casting round billet for the roller sleeve, the production automation degree is increased, the energy consumption is low, and the production cost is effectively reduced through the electric furnace → LF refining → VD vacuum degassing → Phi 700mm continuous casting → annealing; the continuous casting adopts constant drawing speed, controls the superheat degree to be stable, adopts a crystallizer, a casting flow and tail end electromagnetic stirring, protects the casting in the whole process, produces 32Cr3Mo1V continuous casting round billets, has no riser or nozzle, reduces the working procedures of forging and cutting the riser or nozzle, improves the internal quality of the continuous casting billets, reduces the component segregation of molten steel in the solidification process, reduces the central cracks and shrinkage cavities of the continuous casting billets, meets the requirements of forging roller sleeves on low-power quality and central quality, produces the 32Cr3Mo1V roller sleeves by replacing steel ingots with the continuous casting round billets produced by the process, basically has consistent segregation in the length direction, avoids serious defects caused by A-type segregation of longitudinal upward segregation and V-type segregation of longitudinal downward segregation, and prolongs the service life of the roller sleeves.

Detailed Description

In order to make the objects and technical solutions of the present invention clear and fully described, and advantages thereof more clear, embodiments of the present invention are described in further detail below. It is to be understood that the specific embodiments described herein are illustrative of some, but not all embodiments of the invention, and are intended to be exemplary only, and not limiting of the invention, and that all other embodiments obtained by those skilled in the art without making any inventive step are within the scope of the invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal", and the like indicate orientations or positional relationships only for the convenience of description and simplification of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

For the purposes of simplicity and explanation, the principles of the embodiments are described by referring mainly to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that the embodiments may be practiced without these specific details. In some instances, well-known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. In addition, all embodiments may be used in combination with each other.