阅读说明：本技术 一种压力容器用钼合金钢板及其生产方法 (Molybdenum alloy steel plate for pressure container and production method thereof ) 是由 李建朝 李样兵 赵国昌 袁锦程 吴艳阳 龙杰 柳付芳 牛红星 尹卫江 侯敬超 王 于 2019-10-14 设计创作，主要内容包括：本发明公开了一种压力容器用钼合金钢板及其生产方法,所述钢板是由以下重量百分比的组分组成：C 0.22-0.26%,Si 0.35-0.45%,Mn 0.70-0.98%,P≤0.006%,S≤0.005%,Mo 0.41-0.64%,Cr 0.30-0.35%,Ni 0.30-0.40%,Cu 0.10-0.22%,V≤0.050%,Nb≤0.040%,Ti≤0.050%,余量为Fe和不可避免的杂质。生产方法包括冶炼、模铸、轧钢和热处理工序。本发明钢板具有良好的常温拉伸、高温拉伸和低温冲击性能,综合性能优异,完全满足有特殊要求的压力容器用钢板的设计与制造。(The invention discloses a molybdenum alloy steel plate for a pressure container and a production method thereof, wherein the steel plate comprises the following components in percentage by weight: 0.22 to 0.26 percent of C, 0.35 to 0.45 percent of Si, 0.70 to 0.98 percent of Mn, less than or equal to 0.006 percent of P, less than or equal to 0.005 percent of S, 0.41 to 0.64 percent of Mo, 0.30 to 0.35 percent of Cr, 0.30 to 0.40 percent of Ni, 0.10 to 0.22 percent of Cu, less than or equal to 0.050 percent of V, less than or equal to 0.040 percent of Nb, less than or equal to 0.050 percent of Ti, and the balance of Fe and inevitable impurities. The production method comprises the working procedures of smelting, die casting, steel rolling and heat treatment. The steel plate has good normal-temperature stretching, high-temperature stretching and low-temperature impact properties and excellent comprehensive performance, and completely meets the design and manufacture of the steel plate for the pressure container with special requirements.)

1. A molybdenum alloy steel sheet for pressure vessels, characterized in that: the steel plate comprises the following chemical components in percentage by weight: 0.22 to 0.26 percent of C, 0.35 to 0.45 percent of Si, 0.70 to 0.98 percent of Mn, less than or equal to 0.006 percent of P, less than or equal to 0.005 percent of S, 0.41 to 0.64 percent of Mo, 0.30 to 0.35 percent of Cr, 0.30 to 0.40 percent of Ni, 0.10 to 0.22 percent of Cu, less than or equal to 0.050 percent of V, less than or equal to 0.040 percent of Nb, less than or equal to 0.050 percent of Ti, and the balance of Fe and inevitable impurities.

2. The molybdenum alloy steel sheet for pressure vessels as claimed in claim 1, wherein: the thickness of the molybdenum alloy steel plate for the pressure container is 80-152 mm.

3. The molybdenum alloy steel sheet for pressure vessels as claimed in claim 1, wherein: the single value of AKV impact energy of the steel plate at the temperature of 18 ℃ below zero is more than 65 joules.

4. The molybdenum alloy steel sheet for pressure vessels as claimed in claim 1, wherein: the steel plate is cold-bent for d =2a and 180 degrees, and has no crack in appearance, wherein d is the diameter of the bending core, and a is the thickness of the test sample.

5. The molybdenum alloy steel sheet for pressure vessels as claimed in claim 1, wherein: the tensile yield strength Rp0.2 of the steel plate at the high temperature of 550 ℃ is more than or equal to 185 MPa.

6. A production method of a molybdenum alloy steel plate for a pressure vessel is characterized by comprising the following steps: the method comprises the working procedures of smelting, die casting, steel rolling and heat treatment, and comprises the following specific steps:

(1) smelting and die casting: a converter or an electric furnace is adopted for primary smelting, and then the molten steel is refined by an LF furnace and transported to a die casting line for casting after VD vacuum treatment;

(2) a steel rolling procedure: heating to 1200-1350 ℃ in a soaking pit furnace, and rolling after the heating time is 28-36 h;

(3) a heat treatment process: and carrying out normalizing heat treatment on the steel plate to obtain the molybdenum alloy steel plate for the pressure vessel.

7. The method for producing a molybdenum alloy steel sheet for pressure vessels as claimed in claim 6, wherein: the rolling temperature in the steel rolling procedure is 920-1280 ℃, the reduction rate of each pass is less than or equal to 12%, and the steel plate is air-cooled after being completely rolled.

8. The method for producing a molybdenum alloy steel sheet for pressure vessels as claimed in claim 6 or 7, wherein: the normalizing parameters in the normalizing heat treatment procedure are as follows: temperature 850-: 2.0-3.0min/mm, water cooling, and controlling the temperature of the steel plate to return to red 350-440 ℃.

Technical Field

The invention relates to a molybdenum alloy steel plate for a pressure container and a production method thereof, belonging to the technical field of ferrous metallurgy.

Background

In order to meet the requirements of markets, technologies and production development of petrochemical industry and coal chemical industry, boilers and pressure vessels are becoming large, heavy and complex day by day, and the requirements on safety of the boilers and the pressure vessels are becoming increasingly strict. To meet the trend of development, the design institute puts forward higher and stricter technical requirements on the steel plate of the pressure vessel base material, and partial requirements such as J coefficient, X coefficient, Ceq carbon equivalent, negative temperature impact toughness and 550 ℃ high-temperature tensile property are even close to or reach the limit level of the steel plate. In order to meet the above-mentioned severe requirements, steel mills have to increase the content of alloying elements based on the original technical requirements, which inevitably leads to an increase in production cost, and how to obtain a steel plate with better internal properties without increasing the production cost, especially the alloying cost, the rolling cost and the heat treatment cost, is a main problem that needs to be solved urgently by each steel mill.

Disclosure of Invention

The invention aims to provide a molybdenum alloy steel plate for a pressure container, which has excellent comprehensive performance inside and outside, has good obdurability matching, and can meet the use requirements of medium-high temperature and high-pressure environments.

In order to achieve the above object, the molybdenum alloy steel sheet for pressure vessels according to the present invention comprises: a molybdenum alloy steel plate for a pressure vessel comprises the following components in percentage by weight: 0.22 to 0.26 percent of C, 0.35 to 0.45 percent of Si, 0.70 to 0.98 percent of Mn, less than or equal to 0.006 percent of P, less than or equal to 0.005 percent of S, 0.41 to 0.64 percent of Mo, 0.30 to 0.35 percent of Cr, 0.30 to 0.40 percent of Ni, 0.10 to 0.22 percent of Cu, less than or equal to 0.050 percent of V, less than or equal to 0.040 percent of Nb, less than or equal to 0.050 percent of Ti, and the balance of Fe and inevitable impurities.

The thickness of the molybdenum alloy steel plate for the pressure container is 80-152 mm.

The invention also aims to provide a production method of the molybdenum alloy steel plate for the pressure container, which comprises the following steps of smelting, die casting, steel rolling and heat treatment:

(1) smelting and ingot casting: a converter or an electric furnace is adopted for primary smelting, and then the molten steel is refined by an LF furnace and transported to a die casting line for casting after VD vacuum treatment; the steel ingot comprises the following chemical components in percentage by weight: 0.22 to 0.26 percent of C, 0.35 to 0.45 percent of Si, 0.70 to 0.98 percent of MnP, less than or equal to 0.006 percent of P, less than or equal to 0.005 percent of S, 0.41 to 0.64 percent of Mo, 0.30 to 0.35 percent of Cr, 0.30 to 0.40 percent of Ni, 0.10 to 0.22 percent of Cu0.10 percent of V, less than or equal to 0.050 percent of Nb, less than or equal to 0.040 percent of Ti, and the balance of Fe and inevitable impurities.

(2) A steel rolling procedure: heating the soaking pit to 1200-1350 ℃ for 28-36h, and then rolling. The initial rolling temperature is 920-1280 ℃, the reduction rate of each pass is less than or equal to 12%, and the steel plate is air-cooled after being completely rolled.

(3) A heat treatment process: normalizing the steel plate at 850 ℃ and 950 ℃, wherein the total heating time is as follows: 2.0-3.0min/mm, and obtaining the molybdenum alloy steel plate for the pressure vessel after controlling the steel plate to return to the red temperature of 350-440 ℃ by water cooling.

The steel plate has the characteristics of high yield strength of ① and tensile strength, yield strength of more than 290MPa, tensile strength of more than 495MPa, elongation of more than or equal to 22%, AKV impact energy single value of more than 65 joules at ② -18 ℃, ③ cold bending d =2a, 180 degrees and no crack in appearance, wherein d is the diameter of a bending core, a is the thickness of a sample, and the high-temperature tensile yield strength Rp0.2 of ④ 550 ℃ is more than or equal to 185 MPa.

The design idea of the invention is as follows: the invention introduces a novel component design concept, optimizes the proportion of each element in the steel, adopts a low Mn, Mo, Cr, Ni and Cu composite strengthening mechanism, is matched with and added with a small amount of microalloy V, Nb and Ti elements, fully exerts the maximum effect of each element by less content and proportion of alloy elements and ensures that the steel plate has stable and good performance. The C, Mn in the invention can directly influence the strength and plasticity of the steel, within a certain content range, the strength of the steel is gradually increased along with the increase of the content, but the plasticity is reduced, and the welding performance is also reduced at the same time, so the content of the C, Mn is effectively controlled; cr, Mo and Ni elements can enhance the hardenability of steel and improve the strength, toughness and heat strength of the steel, but the alloy cost is increased easily due to excessive addition, and relatively better internal and external properties are obtained by adopting less content of noble alloy elements, which is also one of the innovation points of the patent; a small amount of solid solution formed by microalloy element Nb, V, Ti carbide formed in steel can play the roles of solid solution strengthening, steel structure and grain refinement and steel obdurability matching improvement; the small amount of Cu element can improve the strength and yield ratio of the steel and the corrosion resistance of the steel, but when the content of Cu element is higher, the Cu element is unfavorable for hot deformation processing, and the content of Cu element also needs to be controlled lower. Compared with the conventional production process, the content of the noble alloy elements added into the steel plate is relatively low, the smelting cost and the subsequent production cost are controlled to be low, and the market potential and the competitiveness are great.

The beneficial effect that adopts above-mentioned technical scheme to produce lies in:

the production method provided by the invention adopts a converter or an electric furnace for smelting, the molten steel has high cleanliness, the contents of residual elements and harmful elements in the steel are low, the smelting modes are various, and the operation is convenient. Meanwhile, the addition amount of alloy elements is less, and the smelting cost is obviously reduced; the steel plate is hot rolled into a material by adopting a steel ingot, the compression ratio is large, the defects of loose core and the like can be closed to a greater extent; the heat treatment can be carried out in various furnace types such as a quenching furnace, a normalizing furnace (with NAC function), a vehicle bottom furnace (with a quenching tank) and the like, and the production is easy to arrange. And the steel plate is delivered by normalizing, so that the heat treatment cost is obviously reduced.

The steel plate meets the requirements of normal-temperature stretching, high-temperature stretching and low-temperature impact performance under medium-high temperature environment in the pressure container in the industries of petrochemical industry, coal chemical industry and the like, and is completely suitable for manufacturing the pressure container with special requirements in the industries of petroleum, chemical industry, power stations, boilers and the like, such as equipment and key components of ammonia synthesis towers, gasification furnaces, hydrogenation reactors, coke towers, heat exchangers, condensers and the like.

Detailed Description

The present invention will be described in further detail with reference to examples.