CN116623084A

CN116623084A - Vanadium-nitrogen microalloyed medium-carbon manganese steel for gas cylinders and preparation method thereof

Info

Publication number: CN116623084A
Application number: CN202310578012.1A
Authority: CN
Inventors: 张利平; 郑艳; 杜国强; 叶飞来; 路峰; 梁娜; 张海霞; 赵冠夫
Original assignee: Shandong Iron and Steel Co Ltd
Current assignee: Shandong Iron and Steel Co Ltd
Priority date: 2023-05-22
Filing date: 2023-05-22
Publication date: 2023-08-22

Abstract

The invention belongs to the technical field of metallurgy, in particular to steel for a vanadium-nitrogen microalloyed medium-carbon manganese gas cylinder and a preparation method thereof, and the steel is prepared according to the following steps ofThe chemical components of the steel for the vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder comprise the following components in percentage by mass: c:0.34 to 0.38 percent of Si:0.17 to 0.37 percent of Mn:1.60 to 1.70 percent of N:0.007 to 0.012 percent, V:0.01 to 0.04 percent of Al:0.01 to 0.05 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.010 percent, O is less than or equal to 20 multiplied by 10 ^‑4 ％，H≤2×10 ^‑4 The balance being Fe and other unavoidable impurity elements. The preparation method comprises the following steps: smelting in an electric furnace/converter, refining in an LF furnace, vacuum degassing in VD/RH, continuous casting, hot feeding/slow cooling, rolling into a finished product, normalizing and checking. According to the steel grade, mn, V, N, al element is added into the medium-carbon manganese steel, a proper continuous casting and rolling process is formulated, the performance of the steel after normalizing is improved, and the yield strength, the low-temperature impact toughness and the elongation after breaking of the gas cylinder are ensured to meet the user requirements.

Description

Vanadium-nitrogen microalloyed medium-carbon manganese steel for gas cylinders and preparation method thereof

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to steel for a vanadium-nitrogen microalloyed medium-carbon manganese gas cylinder and a preparation method thereof.

Background

The 37Mn is extremely wide in application as steel for the medium carbon manganese gas cylinder, and the performance of the steel is unstable after normalizing and cannot meet the requirement of a user on the use standard, so that the performance of the steel is improved and stabilized by adding trace alloy elements through reasonable process control means.

Chinese patent application CN103114258A discloses a "37 Mn high-pressure gas bottle blank containing rare earth and its production method", which is made by adopting the production process of "blast furnace molten iron-molten iron pretreatment-converter smelting-LF refining-VD vacuum degassing-calcium treatment-adding rare earth-bloom continuous casting-rolling 200mm x 200mm specification finished product blank-sampling-sample heat treatment-inspection".

Chinese patent application CN105331885a discloses a method for producing 37Mn round billet for gas cylinder, blast furnace, top-bottom combined blown converter, LF refining furnace, VD vacuum furnace, round billet caster, inspection and warehouse entry. The chemical composition of the 37Mn round billet for producing the gas cylinder is strictly controlled, and the whole batch is uniform in supply and small in fluctuation; the top-bottom combined blowing technology is adopted, the blowing is stable, and the hit rate of components and temperature is high; the LF and VD refining process is provided with ladle whole-process bottom argon blowing and ladle wire feeding equipment, so that gas in steel can be effectively removed, the inclusion content in the steel is reduced, and the purity of molten steel is improved; the continuous casting process adopts a crystallizer for electromagnetic stirring and low superheat pouring to ensure the quality of round billets.

Chinese patent CN105695659B discloses a method for producing a steel plate with a cross-section of a size ofThe quality control method of the 37Mn round tube steel casting blank. The method comprises the steps of converter smelting, LF refining molten steel, RH vacuum treatment, continuous casting of molten steel and the like, wherein at first, the purity of the molten steel is improved according to reasonable parameter control in the molten steel smelting stage, the high-temperature plasticity of the molten steel is improved by carrying out micro-titanium treatment on the molten steel, the crack sensitivity of the steel is reduced, then in the molten steel pouring process, the method of combining electromagnetic stirring of a crystallizer with electromagnetic stirring of a solidification tail end is adopted, so that the molten steel component and the temperature are homogenized, a billet shell uniformly grows, the solidification structure of a casting blank is effectively improved, the loosening rating is improved, the area of an equiaxed crystal region is enlarged, the compactness of a round billet central region is effectively improved, the crack defect of the casting blank is effectively controlled, the surface non-cleaning rate is improved, and the quality control of a rolled material is good and stable.

Chinese patent CN105586531B discloses a production method capable of effectively controlling the quality of 37Mn round tube blank steel casting blank, comprising the steps of converter smelting, LF refining, RH vacuum treatment and continuous casting performed sequentially; in the continuous casting step, the electromagnetic stirring parameter of the crystallizer is stirring current of 300-400A and frequency of 2-4 Hz; the electromagnetic stirring parameter of the solidification tail end is stirring current of 100-250A and frequency of 4.0-7.0 Hz; the superheat degree is controlled at 20-35 ℃; the pulling speed is controlled to be 0.75-0.90 m/min; the cooling of the crystallizer is controlled to 2400-2500L/min; the specific water quantity of the secondary cooling is controlled to be 0.21-0.30L/kg of steel.

Chinese patent CN107747041B discloses a normalized manganese gas cylinder steel and a preparation method thereof, wherein the gas cylinder steel comprises the following components in percentage by mass: 0.36 to 0.40 percent of C, 0.17 to 0.37 percent of Si, 1.55 to 1.70 percent of Mn, less than or equal to 0.25 percent of Cr, less than or equal to 0.10 percent of Mo, less than or equal to 0.05 percent of V, less than or equal to 0.005 percent of S, less than or equal to 0.015 percent of P, 40 to 100ppm of N and the balance of Fe. According to the normalized manganese gas cylinder steel and the preparation method thereof, the production process of converter+refining (LF+VD) +continuous casting is adopted, cr, mo, V and N elements are added into the gas cylinder steel, the yield strength and impact toughness of the gas cylinder steel in the normalized state are obviously improved and stabilized through a reasonable slag making system in the refining process, and the subsequent heat treatment cost is saved.

The composition of the steel for gas cylinders disclosed in the above patent application is different from the present invention, and the properties that can be achieved finally are also different. The steel for the gas cylinder provides specific index values of components, low-power, nonmetallic inclusions, performance requirements and the like, and also discloses a production method for producing the steel.

Disclosure of Invention

The invention aims to provide steel for a vanadium-nitrogen microalloyed medium-carbon manganese gas cylinder and a preparation method thereof, wherein Mn, V, N, al elements are added into the medium-carbon manganese steel to prepare a proper continuous casting and rolling process, so that the performance of the steel after normalizing is improved, and the yield strength, the low-temperature impact toughness and the elongation after breaking of the gas cylinder are ensured to meet the requirements of users.

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

the steel for the vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder comprises the following chemical components in percentage by mass: c:0.34 to 0.38 percent of Si:0.17 to 0.37 percent of Mn:1.60 to 1.70 percent of N:0.007 to 0.012 percent, V:0.01 to 0.04 percent of Al:0.01 to 0.05 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.010 percent, O is less than or equal to 20 multiplied by 10 ^-4 ％，H≤2×10 ^-4 ％，The balance of Fe and other unavoidable impurity elements.

In the invention, the low-power tissue grade of the steel for the vanadium-nitrogen microalloyed medium-carbon manganese gas cylinder is less than or equal to 1.0 grade; the fine system of inclusions in steel is less than or equal to 1.0 level, and the coarse system of inclusions in steel is less than or equal to 1.0 level; mechanical properties: tensile strength is more than or equal to 700MPa, yield strength is more than or equal to 520MPa, A is more than or equal to 16, and impact energy KV at minus 20℃ is more than or equal to 16 ₂ ≥27J。

V main action: can refine grains in alloy steel, improves the strength and yield ratio and impact toughness after normalizing, and is the most ideal element for improving the mechanical property.

The main function of N: n can be partially dissolved in iron, has the functions of solid solution strengthening and improving hardenability, can reduce coarsening tendency of crystal grains, and improves toughness and hardenability of steel. However, the N content should not be too high, so that the possibility of forming nitrides with other alloy elements is controlled, and nonmetallic inclusions are formed. The mass percentage of N in the gas cylinder steel is actually controlled to be 0.007-0.011%.

Action of Al: the deoxidizing agent or alloying element is added into steel, and has much stronger deoxidizing ability than silicon and manganese. The main function of Al in steel is to refine grains and fix nitrogen in steel, thereby remarkably improving the impact toughness of steel.

The invention also provides a preparation method of the vanadium-nitrogen microalloyed medium-carbon manganese series steel for the gas cylinder, which comprises the following steps:

smelting in an electric furnace/converter, refining in an LF furnace, vacuum degassing in VD/RH, continuous casting, hot feeding/slow cooling, rolling into a finished product, normalizing and checking.

Preferably, the electric furnace/converter smelting:

foam slag is produced in the smelting process, decarburization is carried out uniformly, the alkalinity of the final slag is controlled to be 2.8-3.4, the tapping endpoint C is more than or equal to 0.10%, P is less than or equal to 0.015%, and the content of residual elements meets the standard requirement; tapping temperature: 1620-1680 ℃.

Preferably, the LF furnace refines:

and controlling the alkalinity of slag to be more than 3.0, enhancing desulfurization operation, and sampling and analyzing white slag.

Preferably, the VD/RH vacuum degassing treatment: the vacuum pure treatment time is more than or equal to 12 minutes, and the soft blowing time is more than or equal to 10 minutes.

Preferably, the rolled product: by usingThe blank is rolled, the preheating section is 500-1000 ℃, the heating section is 1030-1230 ℃, the heating section is 1170-1280 ℃, the soaking section is 1170-1250 ℃, the allowable temperature difference is less than or equal to 30 ℃, and the total heating time is more than or equal to 6 hours.

In the prior art, a continuous casting billet is hot rolled into a tube, and is processed into a seamless gas cylinder. Under the condition of the same chemical components, after the gas cylinder is processed, the quenching and tempering heat treatment production process is used, and the tensile property and the impact toughness completely meet the national standard requirements. However, the mechanical property of the gas cylinder made of the normalized 37Mn steel material is unstable, and the yield strength and the impact energy cannot reach the indexes of the prior art at the same time. The invention produces the gas cylinder which adopts the normalizing heat treatment process and has stable performance and meets the technical index by properly adding trace elements and adjusting the production process, thereby solving the problem that steel factories, steel pipe factories and gas cylinder production enterprises need to jointly solve.

Compared with the prior art, the invention has the following beneficial progress:

the invention produces the round tube blank for the high-pressure gas cylinder with stable performance and technical requirements by applying reasonable component design and operation processes such as smelting, rolling, flaw detection procedures and the like, thereby meeting the process requirements of users for adopting normalizing heat treatment.

Drawings

FIG. 1 is a drawing showing the microstructure of a round tube blank for a high-pressure gas cylinder obtained in example 1;

FIG. 2 is a metallographic structure diagram of a round tube blank for a high-pressure gas cylinder obtained in example 1.

Detailed Description

The technical scheme of the invention is described in detail below with reference to the accompanying drawings and examples.

The steel for the vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder comprises the following components in percentage by mass: c:0.34 to 0.38 percent of Si:0.17 to 0.37 percent of Mn:1.60 to 1.70 percent of N:0.007 to 0.012 percent, V:0.01 to 0.04 percent of Al：0.01～0.05％、P≤0.015％、S≤0.010％、O≤20×10 ^-4 ％，H≤2×10 ^-4 The balance of Fe and other unavoidable impurity elements;

the preparation method comprises the following steps:

the invention is manufactured by adopting the production process of electric furnace/converter smelting, LF furnace refining, VD/RH vacuum degassing treatment, continuous casting (electromagnetic stirring), hot feeding/slow cooling, rolling into a finished product and checking, and the key process is as follows:

electric furnace/converter smelting: foam slag is produced in the smelting process, decarburization is carried out uniformly, the alkalinity of the final slag is controlled to be 2.8-3.4, the tapping endpoint C is more than or equal to 0.10%, P is less than or equal to 0.015%, and the content of residual elements meets the standard requirement; tapping temperature: 1620-1680 ℃.

LF refining: and controlling the alkalinity of slag to be more than 3.0, enhancing desulfurization operation, and sampling and analyzing white slag.

Vacuum degassing treatment by VD/RH: the vacuum pure treatment time is more than or equal to 12 minutes, and the soft blowing time is more than or equal to 10 minutes.

Rolling into a material: by usingThe blank is heated to 500-1000 deg.c in the preheating section, 1030-1230 deg.c in the heating section, 1170-1280 deg.c in the heating section, 1170-1250 deg.c in the soaking section, and the allowable temperature difference is less than or equal to 30 deg.c and the total heating time is less than or equal to 6 hr.

Nondestructive testing: ultrasonic inspection is carried out according to the GB/T4162 standard, the qualification grade is grade B, magnetic leakage inspection is carried out according to the GB/T32547 standard, and the qualification grade is grade 3.

And (3) checking: ingredient, low power, inclusion grade, performance.

Example 1:

the steel for the vanadium-nitrogen microalloyed medium-carbon-manganese gas cylinder is manufactured by adopting the production processes of an electric furnace/converter, LF furnace refining, VD/RH vacuum degassing treatment, continuous casting (electromagnetic stirring), hot feeding/slow cooling, rolling into a material and checking, wherein the key processes are as follows:

adopting an electric furnace for smelting, wherein foam slag is produced in the smelting process, decarburization is uniform, the alkalinity of final slag is controlled at 2.9, and the tapping end point C is as follows: 0.14%, P:0.012%; tapping temperature: 1633 ℃.

LF refining: controlling the alkalinity of slag to be 3.4, enhancing desulfurization operation, and sampling and analyzing white slag.

And (3) performing vacuum degassing treatment by VD: the treatment time was 14 minutes at 61Pa vacuum, and the soft blowing time was 15 minutes.

Rolling into a material: by usingThe above blank is preheated to 850 ℃, heated to 1130 ℃, heated to 1220 ℃, soaked to 1230 ℃ for 6.2 hours.

Nondestructive testing: the ultrasonic inspection level is B level, and the magnetic leakage inspection level is 3 level.

And (3) checking: ingredient, low power, inclusion grade, performance.

The low-power structure chart is shown in fig. 1, the metallographic structure chart is shown in fig. 2, the chemical compositions are shown in table 1, the gas elements and the harmful elements are shown in table 2, the low-power structure grade is shown in table 3, the nonmetallic inclusion grade is shown in table 4, and the mechanical properties are shown in table 5.

TABLE 1 chemical composition (melting analysis)%

C	Si	Mn	P	S	V	Alt
							0.367	0.242	1.611	0.0096	0.0046	0.032	0.0249

TABLE 2 gas elements and harmful elements

T.[O]

[N]

[H]

Sn

Sb

As

Pb

Bi

11.1ppm

86.7ppm

1ppm

0.003％

0.004％

0.005％

0.0002％

0.0005％

TABLE 3 Low-fold tissue grade

General porosity	Center porosity	Center segregation	General punctiform segregation	Edge punctiform segregation
					0.5	0.5	0.5	Without any means for	Without any means for

TABLE 4 nonmetallic inclusion grade

TABLE 5 mechanical Properties

Example 2:

adopting an electric furnace for smelting, wherein foam slag is produced in the smelting process, decarburization is uniform, the alkalinity of final slag is controlled at 3.0, and the tapping end point C is as follows: 0.13%, P:0.012%; tapping temperature: 1641 ℃.

LF refining: and the alkalinity of slag is 3.7, the desulfurization operation is enhanced, and white slag is sampled and analyzed.

And (3) performing vacuum degassing treatment by VD: the treatment time was 13 minutes at a vacuum of 43Pa and the soft blowing time was 15 minutes.

Rolling: by usingThe blank is preheated to 850 ℃, heated to 1120 ℃ in 1 section, heated to 1230 ℃ in 2 section, soaked in 1230 ℃ in 2 section and heated for 6.2 hours.

And (3) checking: ingredient, low power, inclusion grade, performance.

The chemical composition is shown in Table 6, the gas elements and harmful elements are shown in Table 7, the microstructure grade is shown in Table 8, the nonmetallic inclusion grade is shown in Table 9, and the mechanical properties are shown in Table 10.

TABLE 6 chemical composition (melting analysis)%

C	Si	Mn	P	S	V	Alt
							0.361	0.235	1.632	0.0107	0.0021	0.034	0.0235

TABLE 7 gas elements and harmful elements

T.[O]

[N]

[H]

Sn

Sb

As

Pb

Bi

9.8ppm

88.6ppm

0.8ppm

0.003％

0.006％

0.0002％

0.0005％

Table 8 low power group level

General porosity	Center porosity	Center segregation	General punctiform segregation	Edge punctiform segregation
					1.0	0.5	0.5	Without any means for	Without any means for

TABLE 9 nonmetallic inclusion grade

TABLE 10 mechanical Properties

The components, the structure and the performance are uniform, the plasticity is excellent, the yield of the high-pressure gas cylinder is ensured, the produced 37Mn high-pressure gas cylinder has stable performance, higher impact performance reserve margin and excellent comprehensive mechanical property.

Example 3:

adopting an electric furnace for smelting, wherein foam slag is produced in the smelting process, decarburization is uniform, the alkalinity of final slag is controlled at 2.8, and the tapping end point C is as follows: 0.15%, P:0.011%; tapping temperature: 1620 ℃.

LF refining: controlling the alkalinity of slag to 3.1, enhancing desulfurization operation, and sampling and analyzing white slag.

And (3) performing vacuum degassing treatment by VD: the treatment time was 16 minutes at 60Pa vacuum, and the soft blowing time was 14 minutes.

Rolling: by usingThe above blank is preheated to 800 ℃, heated to 1030 ℃, heated to 1170 ℃ and soaked to 1170 ℃ for 6.9 hours.

And (3) checking: ingredient, low power, inclusion grade, performance.

The chemical composition is shown in Table 11, the gas elements and harmful elements are shown in Table 12, the microstructure grade is shown in Table 13, the nonmetallic inclusion grade is shown in Table 14, and the mechanical properties are shown in Table 15.

TABLE 11 chemical composition (melting analysis)%

C	Si	Mn	P	S	V	Alt
							0.342	0.172	1.622	0.0095	0.0045	0.032	0.0213

TABLE 12 gas elements and harmful elements

T.[O]

[N]

[H]

Sn

Sb

As

Pb

Bi

11.2ppm

87.7ppm

2ppm

0.002％

0.005％

0.004％

0.0003％

0.0004％

TABLE 13 Low-fold tissue level

TABLE 14 nonmetallic inclusion grade

TABLE 15 mechanical Properties

Example 4:

adopting an electric furnace for smelting, wherein foam slag is produced in the smelting process, decarburization is uniform, the alkalinity of final slag is controlled at 3.4, and the tapping end point C is as follows: 0.14%, P:0.011%; tapping temperature: 1680 ℃.

LF refining: and the alkalinity of slag is 3.6, the desulfurization operation is enhanced, and white slag is sampled and analyzed.

And (3) performing vacuum degassing treatment by VD: the treatment time was 14 minutes at a vacuum of 43Pa and the soft blowing time was 14 minutes.

Rolling: by usingThe blank is preheated to 900 ℃, heated to 1 section 1230 ℃, heated to 2 sections 1280 ℃, soaked to 1250 ℃ and the total heating time is 6.5 hours.

And (3) checking: ingredient, low power, inclusion grade, performance.

The chemical composition is shown in Table 16, the gas elements and harmful elements are shown in Table 17, the microstructure grade is shown in Table 18, the nonmetallic inclusion grade is shown in Table 19, and the mechanical properties are shown in Table 20.

TABLE 16 chemical composition (melting analysis)%

C	Si	Mn	P	S	V	Alt
							0.370	0.334	1.681	0.0107	0.0021	0.028	0.0212

TABLE 17 gas elements and harmful elements

T.[O]

[N]

[H]

Sn

Sb

As

Pb

Bi

9.4ppm

98.2ppm

0.4ppm

0.001％

0.004％

0.005％

0.0001％

0.0003％

Table 18 low power group level

TABLE 19 nonmetallic inclusion grade

Table 20 mechanical Properties

The method can be realized by the upper and lower limit values of the interval and the interval value of the process parameters (such as temperature, time and the like), and the examples are not necessarily listed here.

The invention may be practiced without these specific details, using any knowledge known in the art.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.

Claims

1. The steel for the vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder is characterized by comprising the following chemical components in percentage by mass: c:0.34 to 0.38 percent of Si:0.17～0.37％、Mn：1.60～1.70％、N：0.007～0.012％、V：0.01～0.04％、Al：0.01～0.05％、P≤0.015％、S≤0.010％、O≤20×10 ^-4 ％，H≤2×10 ^-4 The balance being Fe and other unavoidable impurity elements.

2. The steel for a vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder according to claim 1, wherein the low-power structure grades of the steel for the vanadium-nitrogen microalloyed medium carbon-manganese gas cylinder are all less than or equal to 1.0 grade; the fine system of inclusions in steel is less than or equal to 1.0 level, and the coarse system of inclusions in steel is less than or equal to 1.0 level; mechanical properties: tensile strength is more than or equal to 700MPa, yield strength is more than or equal to 520MPa, A is more than or equal to 16, and impact energy KV at minus 20℃ is more than or equal to 16 ₂ ≥27J。

3. The preparation method of the vanadium-nitrogen microalloyed medium carbon-manganese steel for the gas cylinder comprises the following steps:

4. A method of manufacture according to claim 3, wherein the electric furnace/converter smelting: foam slag is produced in the smelting process, decarburization is carried out uniformly, the alkalinity of the final slag is controlled to be 2.8-3.4, the tapping endpoint C is more than or equal to 0.10%, P is less than or equal to 0.015%, and the content of residual elements meets the standard requirement.

5. A method of manufacture according to claim 3, wherein the electric furnace/converter smelting: tapping temperature: 1620-1680 ℃.

6. A method of manufacture according to claim 3, wherein the LF furnace refines:

7. A method of preparation according to claim 3, wherein the VD/RH vacuum degassing treatment: the vacuum pure treatment time is more than or equal to 12 minutes, and the soft blowing time is more than or equal to 10 minutes.

8. A method of manufacturing according to claim 3, wherein the rolled stock: by usingRolling the blank.

9. A method of manufacturing according to claim 3, wherein the rolled stock: 500-1000 ℃ in the preheating section, 1030-1230 ℃ in the heating section 1, 1170-1280 ℃ in the heating section 2, 1170-1250 ℃ in the soaking section, the allowable temperature difference is less than or equal to 30 ℃, and the total heating time is more than or equal to 6 hours.

10. A method of preparation according to claim 3, wherein the normalizing treatment is carried out at a temperature of 830-870 ℃.