阅读说明：本技术 一种具有低表面裂纹率的高强含磷耐候异型铸坯的制备方法 (Preparation method of high-strength phosphorus-containing weather-resistant special-shaped casting blank with low surface crack rate ) 是由 卜向东 涛雅 卢雄慧 宋振东 冯岩青 周彦 于 2020-05-13 设计创作，主要内容包括：本发明公开了一种具有低表面裂纹率的高强含磷耐候异型铸坯的制备方法,其根据钢水成分特性,合理控制转炉工艺、精炼工艺、VD真空处理工艺、异型坯连铸工艺,有效控制了异型坯连铸过程中漏钢及铸坯表面裂纹率偏高的问题,提高了高强耐候含磷异型坯合格率,铸坯表面裂纹率控制在3％以下。(The invention discloses a preparation method of a high-strength phosphorus-containing weather-resistant beam blank with low surface crack rate, which reasonably controls a converter process, a refining process, a VD vacuum treatment process and a beam blank continuous casting process according to the composition characteristics of molten steel, effectively controls the problems of steel leakage and high surface crack rate of the beam blank in the beam blank continuous casting process, improves the qualification rate of the high-strength weather-resistant phosphorus-containing beam blank, and controls the surface crack rate of the beam blank to be below 3 percent.)

1. A preparation method of a high-strength phosphorus-containing weather-resistant special-shaped casting blank with a low surface crack rate comprises the following smelting processes: converter smelting, LF refining, VD vacuum treatment, beam blank continuous casting and casting blank stacking and slow cooling; the method is characterized in that:

in the process of smelting by the converter, the total oxygen supply at the end point of the converter is controlledThe time is less than 15min, and the total oxygen content is less than 4000m³Ensuring that the primary drawing is carried out, wherein the end point C is more than 0.03 percent, the end point temperature is more than 1620 ℃, the slag discharging amount of the converter is controlled to be less than 50mm, and ferroaluminum is adopted for deoxidation in the converter tapping process;

in the LF refining process, desulfurization, component fine adjustment and heating are carried out according to the components and the temperature of the molten steel of the converter, and ferrocolumbium and ferrophosphorus are added in the later stage of refining to ensure that the components of the molten steel meet the internal control requirement; the LF refining heating time is less than 40min, aluminum-free deoxidation of silicon-calcium-barium is adopted to produce white slag, and the LF dislocation temperature is controlled at 1680-;

in the VD vacuum treatment process, the deep vacuum time is more than or equal to 15min, the deep vacuum degree target is less than 0.1KPa, the weak stirring time after air breaking is more than or equal to 15min, a calcium-silicon wire is fed for 100m, the soft blowing time is more than or equal to 15min, and the temperature after VD is controlled at 1595-1605 ℃;

in the process of the beam blank continuous casting, protective pouring is adopted in the whole process, argon blowing control is carried out at the joint of a ladle and a long nozzle, the lower nozzle is controlled by an asbestos bowl, the insertion depth of the nozzle is 75-85mm, weak cooling is adopted in a secondary cooling mode, the specific water amount of secondary cooling is 0.75-0.85L/kg, the superheat degree is less than or equal to 35 ℃, the melting point of the covering slag is as follows: 1237 ℃, density: 0.85-0.95g/ml, viscosity: 7.90Poise, the constant drawing speed operation is adopted, and the drawing speed of the casting machine is controlled to be 0.7-1.1 m/min; the dummy ingot pressure on 1 frame of withdrawal and straightening machine is 150-160bar, and the dummy ingot pressure on 2-6 frames of withdrawal and straightening machines is 60-70 bar; and stacking and slowly cooling the casting blanks for more than 48 hours.

2. The method for preparing the high-strength phosphorus-containing weather-resistant profiled casting blank with the low surface crack rate as claimed in claim 1, wherein the section size of the continuous casting blank is 350 x 290 x 100mm, 555 x 440 x 105mm, 730 x 370 x 90mm or 1024 x 390 x 120 mm.

3. The method for preparing a high-strength phosphorus-containing weather-resistant profiled casting blank with a low surface crack rate as claimed in claim 1, wherein the surface quality of the high-strength phosphorus-containing weather-resistant steel profiled casting blank is inspected, and the internal quality is inspected with hot acid at a low power.

4. The method according to claim 1, wherein the surface cracking rate of the low surface cracking rate high-strength phosphorus-containing weather-resistant shaped casting slab is less than 3%.

Technical Field

The invention relates to the technical field of smelting and rolling, in particular to a preparation method of a high-strength phosphorus-containing weather-proof special-shaped casting blank with low surface crack rate.

Background

At present, weathering steel tends to be mature and perfect abroad, and has more detailed regulations from the aspects of steel grade development to application, design and construction and the like, and the development and development of the weathering steel are relatively late in China. The weathering steel generally contains elements such as chromium, copper, nickel and the like, a blank shell is easy to adhere to a crystallizer copper plate, so that bonding breakout occurs, meanwhile, C in the weathering steel is mostly located in a sub-peritectic reaction zone, and contains Nb and higher P, the high-temperature plasticity is poor, the surface crack sensitivity is strong, the casting difficulty of the high-strength phosphorus-containing weathering steel is increased due to the particularity of the section of the shaped blank, the surface crack rate of the high-strength phosphorus-containing weathering shaped blank is gradually reduced through continuous groping and steel-making process optimization, and the high-strength phosphorus-containing weathering shaped blank with low surface crack rate is successfully developed.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a preparation method of a high-strength phosphorus-containing weather-resistant special-shaped casting blank with a low surface crack rate.

In order to solve the technical problems, the invention adopts the following technical scheme:

a preparation method of a high-strength phosphorus-containing weather-resistant special-shaped casting blank with a low surface crack rate comprises the following smelting processes: converter smelting, LF refining, VD vacuum treatment, beam blank continuous casting and casting blank stacking and slow cooling; the method is characterized in that:

in the converter smelting process, the total oxygen supply time of the converter end point is controlled to be less than 15min, and the total oxygen content is cumulatively less than 4000m³Ensuring that the primary drawing is carried out, wherein the end point C is more than 0.03 percent, the end point temperature is more than 1620 ℃, the slag discharging amount of the converter is controlled to be less than 50mm, and ferroaluminum is adopted for deoxidation in the converter tapping process;

in the LF refining process, desulfurization, component fine adjustment and heating are carried out according to the components and the temperature of the molten steel of the converter, and ferrocolumbium and ferrophosphorus are added in the later stage of refining to ensure that the components of the molten steel meet the internal control requirement; the LF refining heating time is less than 40min, aluminum-free deoxidation of silicon-calcium-barium is adopted to produce white slag, and the LF dislocation temperature is controlled at 1680-;

in the VD vacuum treatment process, the deep vacuum time is more than or equal to 15min, the deep vacuum degree target is less than 0.1KPa, the weak stirring time after air breaking is more than or equal to 15min, a calcium-silicon wire is fed for 100m, the soft blowing time is more than or equal to 15min, and the temperature after VD is controlled at 1595-1605 ℃;

in the process of the beam blank continuous casting, protective pouring is adopted in the whole process, argon blowing control is carried out at the joint of a ladle and a long nozzle, the lower nozzle is controlled by an asbestos bowl, the insertion depth of the nozzle is 75-85mm, weak cooling is adopted in a secondary cooling mode, the specific water amount of secondary cooling is 0.75-0.85L/kg, the superheat degree is less than or equal to 35 ℃, the melting point of the covering slag is as follows: 1237 ℃, density: 0.85-0.95g/ml, viscosity: 7.90Poise, the constant drawing speed operation is adopted, and the drawing speed of the casting machine is controlled to be 0.7-1.1 m/min; the dummy ingot pressure on 1 frame of withdrawal and straightening machine is 150-160bar, and the dummy ingot pressure on 2-6 frames of withdrawal and straightening machines is 60-70 bar; and stacking and slowly cooling the casting blanks for more than 48 hours.

Furthermore, the section size of the continuous casting billet is 350 multiplied by 290 multiplied by 100mm, 555 multiplied by 440 multiplied by 105mm, 730 multiplied by 370 multiplied by 90mm and 1024 multiplied by 390 multiplied by 120 mm.

Further, the surface quality of the high-strength phosphorus-containing weathering steel special-shaped continuous casting billet is checked, and meanwhile, the internal quality is subjected to hot acid low-power inspection.

Furthermore, the surface crack rate of the prepared high-strength phosphorus-containing weather-resistant profiled casting blank with low surface crack rate is less than 3%.

Compared with the prior art, the invention has the beneficial technical effects that:

the special-shaped casting blank prepared by the method has good surface quality, and the casting blank crack rate is controlled to be below 3%.

Detailed Description

A smelting process of a high-strength phosphorus-containing weather-resistant special-shaped casting blank with a low surface crack rate comprises the following steps: converter smelting, LF refining, VD vacuum treatment, beam blank continuous casting and casting blank stacking and slow cooling;

the chemical components of the material comprise the following components in percentage by mass: 0.07-0.12 percent of C, 0.40-0.60 percent of Si, 0.20-0.50 percent of Mn0.06-0.12 percent of P, less than or equal to 0.015 percent of S, 0.30-0.50 percent of Cr, 0.25-0.40 percent of Cu, 0.20-0.40 percent of Ni, 0.02-0.06 percent of Nb, and the balance of Fe and impurities, wherein the mass fraction is 100 percent;

wherein:

in the converter smelting process, the total oxygen supply time at the end point of the converter is controlled to be less than 15min, the total oxygen content is cumulatively less than 4000m3, the one-time drawing is ensured, the end point C is more than 0.03%, the end point temperature is more than 1620 ℃, the slag discharging amount of the converter is controlled to be less than 50mm, the ferro-aluminum deoxidation is adopted in the converter tapping process, the adding amount is 200kg, the adding amount of a nickel plate is 250kg, the adding amount of a copper plate is 280kg, and the adding amount of low-carbon ferrochrome is.

In the LF refining process, desulfurization, component fine adjustment and heating are carried out according to the components and the temperature of the molten steel of the converter, and ferrocolumbium and ferrophosphorus are added in the later refining stage, so that the components of the molten steel meet the internal control requirement. The LF refining heating time is less than 40min, the silicon-calcium-barium aluminum-free deoxidation is adopted to produce white slag, and the LF dislocation temperature is controlled at 1680-.

In the VD vacuum treatment process: the deep vacuum time is more than or equal to 15min, the deep vacuum degree target is less than 0.1KPa, the weak stirring time after the air breaking is more than or equal to 15min, a calcium silicate wire is fed for 100m, the soft blowing time is more than or equal to 15min, and the temperature after VD is controlled at 1595 and 1605 ℃.

In the process of continuously casting the special-shaped blank: protective pouring is adopted in the whole process, argon blowing control is carried out at the joint of the ladle and the long nozzle, the discharging nozzle is controlled by an asbestos bowl, the insertion depth of the nozzle is 75-85mm, weak cooling is adopted in a secondary cooling mode, the secondary cooling specific water amount is 0.75-0.85L/kg, the superheat degree is less than or equal to 35 ℃, the melting point of the casting powder is as follows: 1237 ℃, density:

0.85-0.95g/ml, viscosity: 7.90Poise, the constant drawing speed is adopted for operation, and the drawing speed of the casting machine is controlled to be 0.7-1.1 m/min. The dummy ingot pressure on 1 frame of withdrawal and straightening machine is 150-160bar, and the dummy ingot pressure on 2-6 frames of withdrawal and straightening machines is 60-70 bar. And stacking and slowly cooling the casting blanks for more than 48 hours.

The section size of the continuous casting billet is 350 multiplied by 290 multiplied by 100mm, 555 multiplied by 440 multiplied by 105mm, 730 multiplied by 370 multiplied by 90mm and 1024 multiplied by 390 multiplied by 120 mm. The surface quality of the high-strength phosphorus-containing weathering steel special-shaped continuous casting billet is checked, and the internal quality is subjected to hot acid low-power inspection.

Obvious quality defects on the surface and inside of the casting blank are not found in the inspection process, the quality of the casting blank is good, and the surface crack rate of the casting blank is lower than 3%.

Tables 1, 2, 3, 4 and 5 further illustrate the present invention with reference to examples.

TABLE 1 control of end point carbon, end point temperature and slag amount in converter smelting process in each example