阅读说明：本技术 一种节镍型奥氏体不锈钢及其制造工艺 (Nickel-saving austenitic stainless steel and manufacturing process thereof ) 是由 赵伟 周嘉晟 冯旺 于 2021-06-20 设计创作，主要内容包括：本发明公开了一种节镍型奥氏体不锈钢及其制造工艺,按重量百分比其化学成分包括：C≤0.15％、Si≤0.5％、Mn≤8.5％、P≤0.05％、S≤0.003％、Cr≤13％、Ni≤0.8％、N≤0.15％、Cu≤0.25％、B≤0.0025％、Mo≤13％,余量为Fe和少量不可避免的杂质,一种节镍型奥氏体不锈钢及其制造工艺包括AOD炉熔炼、LF炉精炼、连铸、热轧加热、粗轧、精轧、卷取,本发明提高解决奥氏体不锈钢加工性能的同时进一步优化控制镍含量,在奥氏体不锈钢中增加钼元素,使各化学元素配比更加合理,使奥氏体不锈钢能够展示出较为优良的耐孔蚀性。(The invention discloses a nickel-saving austenitic stainless steel and a manufacturing process thereof, wherein the nickel-saving austenitic stainless steel comprises the following chemical components in percentage by weight: the invention relates to nickel-saving austenitic stainless steel and a manufacturing process thereof, wherein the nickel-saving austenitic stainless steel comprises the following steps of smelting in an AOD furnace, refining in an LF furnace, continuous casting, hot rolling and heating, rough rolling, finish rolling and coiling, the processing performance of the austenitic stainless steel is improved, the nickel content is further optimized and controlled, the molybdenum element is added into the austenitic stainless steel, the proportion of chemical elements is more reasonable, and the austenitic stainless steel can show excellent hole corrosion resistance.)

1. A nickel-saving austenitic stainless steel and a manufacturing process thereof are characterized in that the nickel-saving austenitic stainless steel comprises the following chemical components by weight percent: less than or equal to 0.15 percent of C, less than or equal to 0.5 percent of Si, less than or equal to 8.5 percent of Mn, less than or equal to 0.05 percent of P, less than or equal to 0.003 percent of S, less than or equal to 13 percent of Cr, less than or equal to 0.8 percent of Ni, less than or equal to 0.15 percent of N, less than or equal to 0.05 percent of Cu, less than or equal to 0.0025 percent of B, less than or equal to 13 percent of Mo, and the balance of Fe and a small amount of inevitable impurities;

the manufacturing process of the nickel-saving austenitic stainless steel comprises the following steps:

step 1, AOD furnace smelting: tapping temperature is 1600-1650 ℃;

step 2, refining in an LF furnace: tapping temperature is 1550-1600 ℃;

step 3, continuous casting, namely continuously passing molten steel through a water-cooled crystallizer, condensing the molten steel into a hard shell, continuously pulling out the hard shell from an outlet below the crystallizer, cooling by spraying water, completely solidifying and cutting into blanks;

step 4, hot rolling and heating: the thickness of the plate blank is 180 mm-220 mm, the furnace entry temperature is 520-560 ℃, the preheating section temperature is 750-900 ℃, the heating time is 20 min-30 min, the preheating section ends and enters a first heating section, the first heating section temperature is 1010-1050 ℃, the time is controlled to be 45 min-55 min, the first heating section ends and enters a second heating section, the second heating section temperature is 1165-1185 ℃, the time is controlled to be 55 min-65 min, the second heating section ends and enters a soaking section, the soaking section temperature is 1285-1295 ℃, the time is controlled to be 40 min-50 min, and the total heating time in the furnace is controlled to be 160 min-200 min;

step 5, rough rolling: the first pass rolling reduction is controlled to be 27.1-29.5%, the second pass rolling reduction is controlled to be 32.1-35.3%, the third pass rolling reduction is controlled to be 36.5-38.4%, the fourth pass rolling reduction is controlled to be 32.3-33.1%, the fifth pass rolling reduction is controlled to be 22.3-23.7%, the first and third passes of descaling are carried out, and the descaling speed is 0.8-1.8 m/s;

step 6, finish rolling: and (3) performing finish rolling by using water for feeding and simultaneously using steam for descaling, wherein the pass reduction rates of 8 finishing mills are respectively F1: 40.1 to 42.1 percent of F2, 38.1 to 39.2 percent of F2, 35.1 to 37.1 percent of F3, 30.1 to 33.4 percent of F4, 25.2 to 28.5 percent of F5, 21.4 to 22.3 percent of F6, 19.1 to 20.8 percent of F7 and 15.2 to 18.1 percent of F8;

step 7, coiling: and (3) applying laminar cooling, wherein the coiling temperature is higher than 680 ℃, immediately stacking and slowly cooling the black skin coil after coiling, and uncoiling, thickness measuring and sampling can be carried out when the temperature is lower than 100 ℃.

2. The nickel-saving austenitic stainless steel and the manufacturing process thereof according to the claim 1, characterized by the steps of 1, AOD furnace smelting: the chemical elements are added with less than or equal to 0.1 percent of C, less than or equal to 0.5 percent of Si, less than or equal to 9 percent of Mn, less than or equal to 13.5 percent of Cr, less than or equal to 0.8 percent of Ni, less than or equal to 0.15 percent of N, less than or equal to 13 percent of Mo, and the balance of low-phosphorus molten scrap iron and high-carbon molten ferromanganese iron according to weight percentage.

3. The nickel-saving austenitic stainless steel and the manufacturing process thereof according to the claim 1, characterized in that the step 2, LF furnace refining: the station-entering time is more than or equal to 60 min/furnace, the strong blowing time is more than or equal to 12min, the weak blowing time is more than or equal to 15min, and the calming time is more than or equal to 15 min.

4. The nickel-saving austenitic stainless steel and the manufacturing process thereof according to the claim 1, characterized by the steps of 3, continuous casting: target temperature corresponds to target pull rate: the specific size is three, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.20-1.25 m/min, the specific size is four, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.20-1.25 m/min, the specific size is five, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.05-1.10 m/min, the usage amount of the crystallizer casting powder is controlled to be 0.4-0.5 kg/ton of steel, and the middle coating covering agent is carbonized rice husks.

5. The nickel-saving austenitic stainless steel and the manufacturing process thereof according to the claims 1 to 4, characterized by the steps of 6, finish rolling: the inlet temperature of finish rolling is 1020-1120 ℃, and the outlet temperature of finish rolling is more than 980 ℃.

Technical Field

The invention belongs to the technical field of austenitic stainless steel processing, and particularly relates to nickel-saving austenitic stainless steel and a manufacturing process thereof.

Background

In the existing nickel-saving austenitic stainless steel, stainless steel production enterprises are also actively developing the nickel-saving austenitic stainless steel, but most of the nickel-saving austenitic stainless steel saves nickel and is added with copper element with higher content, so that the hot working performance is deteriorated, the defects such as edge crack and the like are generated, the yield is influenced, and the surface defects are more in the use process of decoration and the like due to insufficient purity of molten steel and more impurities, and the use of customers is influenced; also, in order to enhance corrosion resistance, the corrosion resistance of austenitic stainless steels is improved by high chromium content and nitrogen, but in certain environments, such as chloride environments, the pitting corrosion resistance is significantly reduced.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides nickel-saving austenitic stainless steel and a manufacturing process thereof, which solve the problem of processing performance of the austenitic stainless steel, further optimize and control the nickel content, and add molybdenum element in the austenitic stainless steel, so that the proportion of all chemical elements is more reasonable, and the austenitic stainless steel can show better pitting corrosion resistance.

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

a nickel-saving austenitic stainless steel and a manufacturing process thereof, the chemical components of which by weight percentage are as follows: less than or equal to 0.15 percent of C, less than or equal to 0.5 percent of Si, less than or equal to 8.5 percent of Mn, less than or equal to 0.05 percent of P, less than or equal to 0.003 percent of S, less than or equal to 13 percent of Cr, less than or equal to 0.8 percent of Ni, less than or equal to 0.15 percent of N, less than or equal to 0.05 percent of Cu, less than or equal to 0.0025 percent of B, less than or equal to 13 percent of Mo, and the balance of Fe and a small amount of inevitable impurities;

the manufacturing process of the nickel-saving austenitic stainless steel comprises the following steps:

step 1, AOD furnace smelting: sequentially adding less than or equal to 0.1 percent of C, less than or equal to 0.5 percent of Si, less than or equal to 0.5 percent of Mn, less than or equal to 9 percent of Mn, less than or equal to 13.5 percent of Cr, less than or equal to 0.8 percent of Ni, less than or equal to 0.15 percent of N, less than or equal to 13 percent of Mo, and the balance of low-phosphorus molten steel scrap and high-carbon molten ferromanganese, wherein the tapping temperature is 1600-1650 ℃;

step 2, refining in an LF furnace: the station entering time is more than or equal to 60 min/furnace, the strong blowing time is more than or equal to 12min, the weak blowing time is more than or equal to 15min, the calming time is more than or equal to 15min, and the tapping temperature is 1550-1600 ℃;

step 3, continuous casting, namely continuously passing molten steel through a water-cooled crystallizer, condensing the molten steel into a hard shell, continuously pulling out the hard shell from an outlet below the crystallizer, cooling by spraying water, completely solidifying and cutting into blanks;

step 4, hot rolling and heating: the thickness of the plate blank is 180 mm-220 mm, the furnace entry temperature is 520-560 ℃, the preheating section temperature is 750-900 ℃, the heating time is 20 min-30 min, the preheating section ends and enters a first heating section, the first heating section temperature is 1010-1050 ℃, the time is controlled to be 45 min-55 min, the first heating section ends and enters a second heating section, the second heating section temperature is 1165-1185 ℃, the time is controlled to be 55 min-65 min, the second heating section ends and enters a soaking section, the soaking section temperature is 1285-1295 ℃, the time is controlled to be 40 min-50 min, and the total heating time in the furnace is controlled to be 160 min-200 min;

step 5, rough rolling: the first pass rolling reduction is controlled to be 27.1-29.5%, the second pass rolling reduction is controlled to be 32.1-35.3%, the third pass rolling reduction is controlled to be 36.5-38.4%, the fourth pass rolling reduction is controlled to be 32.3-33.1%, the fifth pass rolling reduction is controlled to be 22.3-23.7%, the first and third passes of descaling are carried out, and the descaling speed is 0.8-1.8 m/s;

step 6, finish rolling: and (3) removing scale by using steam while feeding water for finish rolling, wherein the inlet temperature of the finish rolling is 1020-1120 ℃, the outlet temperature of the finish rolling is more than 980 ℃, and the pass reduction rates of 8 finish rolling mills are respectively F1: 40.1 to 42.1 percent of F2, 38.1 to 39.2 percent of F2, 35.1 to 37.1 percent of F3, 30.1 to 33.4 percent of F4, 25.2 to 28.5 percent of F5, 21.4 to 22.3 percent of F6, 19.1 to 20.8 percent of F7 and 15.2 to 18.1 percent of F8;

step 7, coiling: and (3) applying laminar cooling, wherein the coiling temperature is higher than 680 ℃, immediately stacking and slowly cooling the black skin coil after coiling, and uncoiling, thickness measuring and sampling can be carried out when the temperature is lower than 100 ℃.

Preferably, step 3, continuous casting: target temperature corresponds to target pull rate: the specific size is three, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.20-1.25 m/min, the specific size is four, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.20-1.25 m/min, the specific size is five, the middle package temperature is 1468-1479 ℃, the corresponding pulling speed is 1.05-1.10 m/min, the usage amount of the crystallizer casting powder is controlled to be 0.4-0.5 kg/ton of steel, and the middle coating covering agent is carbonized rice husks.

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

1) according to the invention, the nickel content in the austenitic stainless steel is further controlled and optimized, the nickel content in the stainless steel is reduced, the production cost can be further reduced, the production stability of the austenitic stainless steel is ensured, and meanwhile, in the finish rolling process, the inlet temperature is increased, the black skin is coiled and then stacked for slow cooling, so that the processing performance of the subsequent austenitic stainless steel is improved.

2) The austenitic stainless steel containing chromium, nitrogen and molybdenum is formed by increasing molybdenum element in the austenitic stainless steel, so that the application range is enlarged, the corrosion resistance is further enhanced, and the austenitic stainless steel can show excellent pitting corrosion resistance and interstitial corrosion resistance even in an environment with strong corrosion.

Detailed Description

For the convenience of understanding of those skilled in the art, the technical solution of the present invention is further specifically described below with reference to examples 1 to 3.

Example 1:

the chemical components by weight percentage are as follows: 0.15% of C, 0.5% of Si, 8.5% of Mn, 0.05% of P, 0.003% of S, 13% of Cr, 0.8% of Ni, 0.15% of N, 0.05% of Cu, 0.0025% of B, 13% of Mo, and the balance of Fe and a small amount of unavoidable impurities;

the manufacturing process of the nickel-saving austenitic stainless steel comprises the following steps:

step 1, AOD furnace smelting: sequentially adding 0.1 percent of C, 0.5 percent of Si, 9 percent of Mn, 13.5 percent of Cr, 0.8 percent of Ni, 0.15 percent of N, 13 percent of Mo and the balance of low-phosphorus molten steel scrap and high-carbon molten ferromanganese iron according to the weight percentage, and tapping at 1600-1650 ℃;

step 2, refining in an LF furnace: the station entering time is more than or equal to 60 min/furnace, the strong blowing time is more than or equal to 12min, the weak blowing time is more than or equal to 15min, the calming time is more than or equal to 15min, and the tapping temperature is 1550-1600 ℃;

step 3, continuous casting, namely continuously passing molten steel through a water-cooled crystallizer, condensing the molten steel into a hard shell, continuously pulling out the hard shell from an outlet below the crystallizer, cooling by spraying water, completely solidifying and cutting into blanks;

step 4, hot rolling and heating: the thickness of the plate blank is 180 mm-220 mm, the furnace entry temperature is 520-560 ℃, the preheating section temperature is 750-900 ℃, the heating time is 20min, the preheating section finishes entering a first heating section, the first heating section temperature is 1010-1050 ℃, the time is controlled at 45min, the first heating section finishes entering a second heating section, the second heating section temperature is 1165-1185 ℃, the time is controlled at 55min, the second heating section finishes entering a soaking section, the soaking section temperature is 1285-1295 ℃, the time is controlled at 40min, and the total heating time in the furnace is controlled at 160 min;

step 5, rough rolling: the first pass reduction rate is controlled to be 27.1 percent, the second pass reduction rate is controlled to be 32.1 percent, the third pass reduction rate is controlled to be 36.5 percent, the fourth pass reduction rate is controlled to be 32.3 percent, the fifth pass reduction rate is controlled to be 22.3 percent, the first pass and the third pass are descaled, and the descaling speed is 1.5 m/s;

step 6, finish rolling: and (3) removing scale by using steam while feeding water for finish rolling, wherein the inlet temperature of the finish rolling is 1020-1120 ℃, the outlet temperature of the finish rolling is more than 980 ℃, and the pass reduction rates of 8 finish rolling mills are respectively F1: 40.1 percent, 38.1 percent of F2, 35.1 percent of F3, 30.1 percent of F4, 25.2 percent of F5, 21.4 percent of F6, 19.1 percent of F7 and 15.2 percent of F8;

step 7, coiling: and (3) applying laminar cooling, wherein the coiling temperature is higher than 680 ℃, immediately stacking and slowly cooling the black skin coil after coiling, and uncoiling, thickness measuring and sampling can be carried out when the temperature is lower than 100 ℃.

Wherein, the step 3 is continuous casting: the target temperature versus target pull rate is as follows:

fixed size	The temperature of the middle ladle is lower	Corresponding pulling speed/m/min
			Three-ruler	1470	1.21
Four-ruler	1470	1.21
			Five-ruler	1475	1.05

Covering agent and crystallizer covering slag are coated in the tundish, and the using amount of the covering slag is controlled to be 0.4 kg/ton steel:

tundish covering agent	Mold flux
		Carbonized rice husk	LY～200

Example 2:

the difference compared to example 1 is:

step 4, hot rolling and heating: the thickness of the plate blank is 180 mm-220 mm, the furnace entry temperature is 520-560 ℃, the preheating section temperature is 750-900 ℃, the heating time is 25min, the preheating section finishes entering a first heating section, the first heating section temperature is 1010-1050 ℃, the time is controlled at 50min, the first heating section finishes entering a second heating section, the second heating section temperature is 1165-1185 ℃, the time is controlled at 60min, the second heating section finishes entering a soaking section, the soaking section temperature is 1285-1295 ℃, the time is controlled at 45min, and the total heating time in the furnace is controlled at 180 min;

step 5, rough rolling: the first pass rolling reduction is controlled to be 28.5 percent, the second pass rolling reduction is controlled to be 34.3 percent, the third pass rolling reduction is controlled to be 37.4 percent, the fourth pass rolling reduction is controlled to be 33.1 percent, the fifth pass rolling reduction is controlled to be 23.7 percent, the first pass rolling reduction and the third pass rolling reduction are carried out, and the descaling speed is 1.3 m/s;

step 6, finish rolling: and (3) removing scale by using steam while feeding water for finish rolling, wherein the inlet temperature of the finish rolling is 1020-1120 ℃, the outlet temperature of the finish rolling is more than 980 ℃, and the pass reduction rates of 8 finish rolling mills are respectively F1: 41.1 percent, 38.5 percent of F2, 36.1 percent of F3, 32.4 percent of F4, 27.5 percent of F5, 22.3 percent of F6, 19.5 percent of F7 and 17.1 percent of F8.

Wherein, the step 3 is continuous casting: the target temperature corresponds to the target pull rate as follows:

fixed size	The temperature of the middle ladle is lower	Corresponding pulling speed/m/min
			Three-ruler	1475	1.22
Four-ruler	1476	1.22
			Five-ruler	1478	1.08

Tundish covering agent and crystallizer covering slag:

the using amount of the covering slag is controlled to be 0.45 kg/ton steel

Tundish covering agent	Mold flux
		Carbonized rice husk	ST～SP200

Example 3:

the difference compared to example 1 is:

step 4, hot rolling and heating: the thickness of the plate blank is 180 mm-220 mm, the furnace entry temperature is 520-560 ℃, the temperature of the preheating section is 750-900 ℃, the heating time is 25min, the preheating section finishes entering a first heating section, the temperature of the first heating section is 1010-1050 ℃, the time is controlled at 55min, the first heating section finishes entering a second heating section, the temperature of the second heating section is 1165-1185 ℃, the time is controlled at 60min, the second heating section finishes entering a soaking section, the temperature of the soaking section is 1285-1295 ℃, the time is controlled at 50min, and the total heating time in the furnace is controlled at 190 min;

step 5, rough rolling: the first pass rolling reduction is controlled to be 29.5 percent, the second pass rolling reduction is controlled to be 35.3 percent, the third pass rolling reduction is controlled to be 38.4 percent, the fourth pass rolling reduction is controlled to be 33.1 percent, the fifth pass rolling reduction is controlled to be 23.7 percent, the first pass rolling reduction and the third pass rolling reduction are carried out, and the descaling speed is 1.6 m/s;

step 6, finish rolling: and (3) removing scale by using steam while feeding water for finish rolling, wherein the inlet temperature of the finish rolling is 1020-1120 ℃, the outlet temperature of the finish rolling is more than 980 ℃, and the pass reduction rates of 8 finish rolling mills are respectively F1: 42.1 percent, F2:39.2 percent, F3:37.1 percent, F4:33.4 percent, F5:28.5 percent, F6:22.3 percent, F7:20.8 percent and F8:18.1 percent.

Wherein, the step 3 is continuous casting: the target temperature versus target pull rate is as follows:

fixed size	The temperature of the middle ladle is lower	Corresponding pulling speed/m/min
			Three-ruler	1478	1.25
Four-ruler	1478	1.22
			Five-ruler	1468	1.05

Tundish covering agent and crystallizer covering slag:

the using amount of the covering slag is controlled to be 0.5 kg/ton steel

Tundish covering agent	Mold flux
		Carbonized rice husk	ST～SP200

Comparative example 1:

CN102943220B, a nickel-saving austenitic stainless steel and a manufacturing method thereof, the components of which by weight percentage are: less than 0.10 percent of C, less than or equal to 1.00 percent of Si, less than or equal to 12.0 percent of Mn with the concentration of 9.0 percent and less than or equal to 12.0 percent, less than or equal to 0.045 percent of S, less than or equal to 0.060 percent of P, less than or equal to 3.0 percent of Ni with the concentration of 1.0 percent and less than or equal to 3.0 percent, less than or equal to 16.0 percent of Cr with the concentration of 13.0 percent and less than or equal to 16.0 percent, less than or equal to 1.0 percent of Cu with the concentration of 0.1 percent and less than or equal to 1.0 percent, less than or equal to 0.2 percent of N, less than or equal to 30 multiplied by 10 percent of B^～4％、20×10^～4％≤Ca≤60×10^～4Percent and the balance of Fe.

Comparative example 2:

the difference from example 1 is: the nickel-saving austenitic stainless steel does not contain molybdenum elements in chemical components, and the chemical elements comprise the following components in percentage by weight: 0.13% of C, 0.45% of Si, 8.7% of Mn, 0.05% of P, 0.003% of S, 9.7% of Cr, 0.6% of Ni, 0.14% of N, 0.25% of Cu, and 0.0025% of B.

Test example:

rolling a steel blank with the plate blank thickness of 200mm into steel coils, respectively sampling the stainless steel strip steel prepared by the four embodiments, respectively placing the stainless steel strip steel in a humid environment and a chloride-containing environment, and carrying out surface observation, wherein the following is a sample observation record table:

as described above, according to the present invention, by increasing the molybdenum element in the austenitic stainless steel to form the austenitic stainless steel containing chromium, nitrogen, and molybdenum, the corrosion resistance of the austenitic stainless steel can be further enhanced, and the austenitic stainless steel can exhibit excellent pitting corrosion resistance and crevice corrosion resistance even in an environment with high corrosion resistance.

The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the present invention as defined in the accompanying claims.