阅读说明：本技术 深海连接器用25%Cr大壁厚超级双目不锈钢锻件的生产工艺 (Production process of 25% Cr large-wall-thickness super binocular stainless steel forging for deep sea connector ) 是由 葛辉 周勇 于 2021-07-21 设计创作，主要内容包括：本发明公开了一种深海连接器用25％Cr大壁厚超级双目不锈钢锻件的生产工艺：下料：取化学成分及重量百分比为：C:≤0.03、Si:≤1.0、Mn:≤1.0、S:≤0.01、P:≤0.03、Cr:24～26、Ni:6～8、Mo:3～4、Cu:0.5～1.0、W:0.5～1.0、N:0.2～0.3、PREN:40～45的钢坯为原料,其中,PREN＝％Cr+3.3x(％Mo+0.5％W)+16x％N；锻造；固溶退火；无损探伤及机械加工。本发明的优点在于：在壁厚达到360mm以上,最大热处理状态厚度200mm的探伤合格时,还能满足机械性能、屈服强度、低温冲击韧性及耐腐蚀性能测试。(The invention discloses a production process of a 25% Cr large-wall-thickness super binocular stainless steel forging for a deep sea connector, which comprises the following steps: blanking: taking the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 1.0, S is less than or equal to 0.01, P is less than or equal to 0.03, Cr is 24-26, Ni is 6-8, Mo is 3-4, Cu is 0.5-1.0, W is 0.5-1.0, N is 0.2-0.3, and PREN is 40-45, wherein PREN is Cr +3.3x (% Mo + 0.5% W) +16 x% N; forging; solution treatment annealing; nondestructive inspection and machining. The invention has the advantages that: when the wall thickness reaches more than 360mm and the flaw detection of the maximum heat treatment state thickness of 200mm is qualified, the mechanical property, yield strength, low-temperature impact toughness and corrosion resistance test can be met.)

1. the production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector is characterized by comprising the following steps of: the production steps are as follows:

a. blanking: taking the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 1.0, S is less than or equal to 0.01, P is less than or equal to 0.03, Cr is 24-26, Ni is 6-8, Mo is 3-4, Cu is 0.5-1.0, W is 0.5-1.0, N is 0.2-0.3, PREn is 40-45, wherein PREN is Cr +3.3x (% Mo + 0.5% W) +16 x% N;

b. forging: placing the steel billet into a forging furnace, firstly heating the steel billet to 300 ℃ from room temperature and preserving heat for more than or equal to 2 hours, then heating the steel billet at 300 ℃ to 750 ℃ and preserving heat for more than or equal to 1 hour, finally heating the steel billet at 750 ℃ to 1180 +/-10 ℃ and preserving heat for more than or equal to 5 hours, then forging the steel billet to forge the steel billet into a connector forge piece, wherein in the forging process, the initial forging temperature is 1180 +/-10 ℃, the final forging temperature is 1040 +/-10 ℃, the drawing ratio is more than 2:1, the upsetting ratio is more than 2.5:1 and the total forging ratio is more than 5:1, and cooling the steel billet to room temperature by water after forging;

c. solution annealing: heating the connector forging to 250 ℃ and preserving heat for 1h, heating the connector forging at 250 ℃ to 450 ℃ and preserving heat for 2h, then heating the connector forging at 450 ℃ to 1130 +/-10 ℃ and preserving heat, wherein the heat preservation time is controlled to be more than 0.5 hour/inch (inch is the maximum wall thickness of the connector forging); finally transferring the connector forging into cooling water within 60 seconds to carry out rapid water cooling to below 32 ℃, and controlling the temperature of the cooling water within 30 ℃ in the water cooling process;

d. and carrying out nondestructive inspection and machining.

2. The production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector according to claim 1, is characterized in that: in the feeding step, a smelting process of an electric furnace, an AOD/VODC furnace and argon protection casting is adopted.

3. The production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector according to claim 1, is characterized in that: the heating rate during forging is controlled to be not higher than 150 ℃/h.

4. The production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector according to claim 1, is characterized in that: the heating rate during the solution annealing is controlled to be not higher than 100 ℃/h.

Technical Field

The invention relates to the application field of high-performance forging materials for high-end equipment in deep sea, in particular to a production process of a 25% Cr large-wall-thickness super binocular stainless steel forging for a deep sea connector.

Background

China is a large oil and gas import country, and long-term dependence on import can limit the development of our country. Fortunately, the sea has a wide territorial sea, and what is called the treasure under the sea is urgently to be developed. The research of the technology of the underwater oil and gas production system in China is relatively late, for a long time, the underwater equipment used in the offshore oil and gas field in China mostly depends on import, the purchase and maintenance cost is high, the supply period is long, and the development of the offshore oil and gas field in China is greatly limited. The mainstream grade of the traditional duplex stainless steel in China is F51 and F60(UNS 31803 and UNS 32205), and the super duplex stainless steel has small production and application amount and small wall thickness.

Super duplex stainless steel A182F 53 belongs to high alloy steel of 25Cr-7Ni-4 Mo-N2, and super duplex stainless steel A182F 55 belongs to high alloy steel of 25Cr-7.5Ni-3.5 Mo-N-Cu-W2. The quality of the final heat treatment process control is the most important factor for influencing the quality of the forged piece. In the case of F53 and F55, a large amount of harmful intermetallic compounds (sigma phase) are easily generated in the material within the temperature range of 320-955 ℃, in the case of F53 and F55, the PREN value needs to be increased to prevent seawater corrosion, however, the risk of forming harmful sigma phase in the material is increased along with the increase of the content of Cu, W and other alloys, the harmful sigma phase is increased, particularly when a forged piece with the wall thickness of 300mm is produced, the forged piece is easy to crack in the forging process and the heat treatment, the yield strength of the forged piece is lower than 550MPa, and the low-temperature impact toughness and corrosion at minus 46 ℃ are easy to fail in testing.

Disclosure of Invention

In order to solve the problems that the super binocular stainless steel is easy to crack and is unqualified in mechanical property when a forged piece with the wall thickness of more than 300mm is produced, the invention provides a production process of a 25% Cr large-wall-thickness super binocular stainless steel forged piece for a deep sea connector, the cracking of the forged piece is reduced by improving a forging process and a heat treatment process, and the mechanical property of the forged piece is ensured to meet the high-level requirement.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: the production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector comprises the following production steps:

a. blanking: taking the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 1.0, S is less than or equal to 0.01, P is less than or equal to 0.03, Cr is 24-26, Ni is 6-8, Mo is 3-4, Cu is 0.5-1.0, W is 0.5-1.0, N is 0.2-0.3, and PREN is 40-45, wherein PREN is Cr +3.3x (% Mo + 0.5% W) +16 x% N;

b. forging: placing the steel billet into a forging furnace, firstly heating the steel billet to 300 ℃ from room temperature and preserving heat for more than or equal to 2 hours, then heating the steel billet at 300 ℃ to 750 ℃ and preserving heat for more than or equal to 1 hour, finally heating the steel billet at 750 ℃ to 1180 +/-10 ℃ and preserving heat for more than or equal to 5 hours, then forging the steel billet to forge the steel billet into a connector forge piece, wherein in the forging process, the initial forging temperature is 1180 +/-10 ℃, the final forging temperature is 1040 +/-10 ℃, the drawing ratio is more than 2:1, the upsetting ratio is more than 2.5:1 and the total forging ratio is more than 5:1, and cooling the steel billet to room temperature by water after forging;

c. solution annealing: heating the connector forging to 250 ℃ and preserving heat for 1h, heating the connector forging at 250 ℃ to 450 ℃ and preserving heat for 2h, then heating the connector forging at 450 ℃ to 1130 +/-10 ℃ and preserving heat, wherein the heat preservation time is controlled to be more than 0.5 hour/inch (inch is the maximum wall thickness of the connector forging); finally transferring the connector forging into cooling water within 60 seconds to carry out rapid water cooling to below 32 ℃, and controlling the temperature of the cooling water within 30 ℃ in the water cooling process;

d. and carrying out nondestructive inspection and machining.

Further, the production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector comprises the following steps of smelting in an electric furnace, an AOD/VODC furnace and argon protection casting.

Further, according to the production process of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector, the heating rate in the forging process is controlled to be not higher than 150 ℃/h.

Further, in the production process of the 25% Cr large-wall-thickness super-binocular stainless steel forging for the deep sea connector, the heating rate in the solution annealing process is controlled to be not higher than 100 ℃/h.

The invention has the advantages that: the 25 percent CR large-wall-thickness super duplex stainless steel forging produced by the process of the invention controls the increase of harmful intermetallic compounds (sigma phase) in the forging and heat treatment processes under the condition of meeting the requirement of PREN component control, ensures that a complete forging product qualified for flaw detection can be obtained after forging and heat treatment, when the wall thickness of the 25 percent CR large-wall-thickness super duplex stainless steel forging reaches more than 360mm and the flaw detection of the maximum heat treatment state thickness of 200mm is qualified (according to the requirements of API 6A PSL3 and deepwater forgings), the alloy can also meet the requirements of mechanical property yield strength of more than or equal to 550MPa, low-temperature impact toughness at minus 46 ℃, hardness, metallographic phase and corrosion resistance test for 24 hours by ASTM G48 method A in 50-degree ferric trichloride solution, has qualified quality and meets the technical indexes of design and use requirements and the high-level standards of international advanced deep-sea engineering material standards NORSOK M-650 and M-630. The service life of the deep sea manifold or the pipeline connector is up to 20 years, the deep sea manifold or the pipeline connector is not damaged, and the quality is ensured to be in a good state.

Detailed Description

The technical solution of the present invention will be further explained with reference to the preferred embodiments.

The invention relates to a production process of a 25% Cr large-wall-thickness super binocular stainless steel forging for a deep sea connector, which comprises the following production steps:

a. blanking: taking the following chemical components in percentage by weight: c is less than or equal to 0.03, Si is less than or equal to 1.0, Mn is less than or equal to 1.0, S is less than or equal to 0.01, P is less than or equal to 0.03, Cr is 24-26, Ni is 6-8, Mo is 3-4, Cu is 0.5-1.0, W is 0.5-1.0, N is 0.2-0.3, and PREN is 40-45, wherein PREN is Cr +3.3x (% Mo + 0.5% W) +16 x% N; then, a smelting process of an electric furnace, an AOD/VODC furnace and argon protection casting is adopted, so that the excessive oxide formed in the casting process is prevented;

b. forging: placing a steel billet into a forging furnace, heating the steel billet at a heating rate of not higher than 150 ℃/h, firstly heating the steel billet to 300 ℃ from room temperature and preserving heat for more than or equal to 2h, then heating the steel billet at 300 ℃ to 750 ℃ and preserving heat for more than or equal to 1h, finally heating the steel billet at 750 ℃ to 1180 +/-10 ℃ and preserving heat for more than or equal to 5h, then forging the steel billet, forging the steel billet into a connector forging piece, wherein the initial forging temperature is 1180 +/-10 ℃, the final forging temperature is 1040 +/-10 ℃, the drawing-out ratio is controlled to be more than 2:1, the upsetting ratio is more than 2.5:1 and the total forging ratio is more than 5:1 in the forging process, and cooling the steel billet to room temperature by water after the forging is finished;

c. solution annealing: heating the connector forging at a heating rate of not higher than 100 ℃/h, heating the connector forging to 250 ℃ and preserving heat for 1h, then heating the connector forging at 250 ℃ to 450 ℃ and preserving heat for 2h, then heating the connector forging at 450 ℃ to 1130 +/-10 ℃ and preserving heat, wherein the heat preservation time is controlled to be more than 0.5 hour/inch (inch is the maximum wall thickness dimension of the connector forging); finally transferring the connector forging into cooling water within 60 seconds to carry out rapid water cooling to below 32 ℃, and controlling the temperature of the cooling water within 30 ℃ in the water cooling process;

d. and carrying out nondestructive inspection and machining.

The mechanical test results of the 25% Cr large-wall-thickness super binocular stainless steel forging for the deep sea connector manufactured by the production process are as follows: