CN112226688A

CN112226688A - Corrosion-resistant and biological-adhesion-resistant EH690 steel plate and manufacturing method thereof

Info

Publication number: CN112226688A
Application number: CN202011054693.4A
Authority: CN
Inventors: 朱隆浩; 赵坦; 金耀辉; 李家安; 于浩男; 任子平; 王�华; 王东旭; 韩鹏; 冯丹竹
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-01-15
Anticipated expiration: 2040-09-30
Also published as: CN112226688B

Abstract

The invention discloses a corrosion-resistant and biological adhesion-resistant EH690 steel plate and a manufacturing method thereof. The steel contains: 0.09 to 0.12 percent of C, 0.15 to 0.35 percent of Si, 1.0 to 1.5 percent of Mn, 0.02 to 0.03 percent of P, less than or equal to 0.01 percent of S, 0.01 to 0.03 percent of Als, 1.5 to 3.0 percent of Ni, 0.3 to 0.6 percent of Cr, 0.3 to 0.5 percent of Mo, 0.5 to 1.5 percent of Cu, 0.03 to 0.06 percent of V, 0.005 to 0.02 percent of Ti, 0.0005 to 0.001 percent of B, 0.005 to 0.3 percent of Sb, 0.005 to 0.3 percent of Sn, and the balance of Fe and inevitable impurities. The first-stage initial rolling temperature is 1000-1050 ℃, the second-stage initial rolling temperature is 900-1000 ℃, the accumulated reduction rate of the second-stage rolling is 40-60%, and the final rolling temperature is 900-950 ℃; the quenching temperature is 830-870 ℃, the heat preservation time is 1.0-2.0 min/mm, the tempering temperature is 600-630 ℃, the heat preservation time is 2-3 min/mm, and the cooling rate after tempering is 5-15 ℃/s. The steel plate has excellent marine environment corrosion resistance.

Description

Corrosion-resistant and biological-adhesion-resistant EH690 steel plate and manufacturing method thereof

Technical Field

The invention belongs to the field of steel material preparation, and particularly relates to a composition design and a manufacturing method of an EH690 ultrahigh-strength marine steel plate with marine environment corrosion resistance and biological adhesion resistance.

Background

The 21 st century is the ocean century, and with the development of science and technology and the improvement of the living standard of people, all countries in the world focus on huge resources stored in the ocean. In recent years, the maritime work equipment industry is continuously and rapidly developed, the massive demand of steel for maritime work platforms and the upgrading and updating of products are promoted, and the market urgently needs ultrahigh-strength and extra-thick maritime work steel plates with good comprehensive performance.

The ocean engineering platform has a severe service environment, besides conventional stress, the influence of various factors such as strong wind, surge, tide, ice impact, earthquake and the like is also considered, so that the specificity of the steel for the ocean platform is determined, and the ocean engineering platform can adapt to various sea conditions in the aspect of material selection of platform construction. Meanwhile, the steel plate is in a humid and high-salinity marine environment for a long time, and the problems of paint film falling, corrosion of the surface of the steel plate, corrosion fatigue and the like caused by adhesion of humid air, seawater and marine organisms are solved, the mechanical property of the steel plate is reduced, the service life is shortened, and the normal use of the ocean engineering platform is seriously influenced. In addition, the ocean platform is far away from the coast and cannot be periodically docked for maintenance like a ship. In order to ensure that the ocean engineering platform can be safely used in a complex environment, a high-quality ultrahigh-strength steel for ocean engineering with excellent comprehensive performance is urgently needed to be developed, and the ultrahigh-strength steel plate for ocean engineering has the advantages of high strength, high and low temperature toughness, low yield ratio, high ductility, fatigue resistance, hydrogen induced cracking resistance, marine environmental corrosion resistance, marine organism adhesion resistance, excellent welding performance and the like.

At present, steel for ocean engineering can meet most of requirements of the market in the field of maritime work, but special steel with excellent comprehensive performance at a high strength level is still the target of development of all countries in the world, and an EH690 steel plate with marine environment corrosion resistance and biological adhesion resistance has high difficulty in scientific research, strict production process, high requirement on equipment and high development difficulty.

The patent of CN106756593A, seawater corrosion resistant steel and its manufacturing method, provides a seawater corrosion resistant steel plate and its production method, the invention adopts lower alloy components and TMCP process to produce steel plate with thinner thickness and lower yield strength.

Patent CN106756602A entitled "high humidity and heat resistant ocean atmosphere high strength weathering steel" proposes a corrosion resistant steel plate with yield strength of 700MPa, which contains 0.01-0.03% of C and 0.3-0.5% of Mn, and cannot produce high strength large thickness steel plates, and the patent does not propose a suitable production process.

Patent CN103741056A, corrosion resistant steel plate for resisting south sea marine environment and production process thereof, provides a marine environment corrosion resistant steel plate, the yield strength and the thickness of which can not meet the requirements of key structures of marine engineering platforms.

CN104419871A patent of Steel for welding Structure with Excellent resistance to Corrosion in Marine Environment and manufacturing method thereof proposes a Steel plate for TMCP welding Structure with yield strength of 235-550 MPa, and the alloy composition and production process thereof can not produce ultra-high strength marine steel plate with large thickness, seawater corrosion resistance and biological adhesion resistance.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and the ultrahigh-strength steel plate which is resistant to marine environmental corrosion and biological adhesion and has high service safety performance and is suitable for the field of marine engineering is prepared, and the corrosion resistance and the service safety performance of the ultrahigh-strength steel plate can reach the service conditions of marine engineering equipment. Forming a set of specific seawater corrosion resistant and biological-attached-resistant ultrahigh-strength marine steel plate components and a corresponding production process.

The invention utilizes the key production technology of marine steel plates which are matched with Cu, Ni, Mo, Sb and Sn and are resistant to marine environmental corrosion, and in order to achieve the aim of the invention, the inventor carries out a large number of systematic experimental researches on aspects of screening and proportioning of alloy elements, control of steel cleanliness, optimization of high-efficiency rolling heat treatment process, parameter selection and the like, and finally determines the alloy element proportioning and rolling heat treatment process which can meet the aim of the invention, and the specific technical scheme is as follows:

an EH690 steel plate with seawater corrosion resistance and biological adhesion resistance comprises the following components in percentage by weight: 0.09 to 0.12 percent of C, 0.15 to 0.35 percent of Si, 1.0 to 1.5 percent of Mn, 0.02 to 0.03 percent of P, less than or equal to 0.01 percent of S, 0.01 to 0.03 percent of Als, 1.5 to 3.0 percent of Ni, 0.3 to 0.6 percent of Cr, 0.3 to 0.5 percent of Mo, 0.5 to 1.5 percent of Cu, 0.03 to 0.06 percent of V, 0.005 to 0.02 percent of Ti, 0.0005 to 0.001 percent of B, 0.005 to 0.3 percent of Sb, 0.005 to 0.3 percent of Sn, and the balance of Fe and inevitable impurities.

The design reason of the chemical components of the steel grade is as follows:

(1) c is used as a basic strengthening element in steel, is a main element for ensuring the strength and the hardness in the scheme of the invention, and has unobvious grain refinement effect when the content of C is too low, so that the strength of the steel plate is reduced. The steel plate has low corrosion resistance and high welding crack tendency due to the over-high content of C, so the content of C in the steel is accurately controlled, and the content of C is controlled to be 0.09-0.12%.

(2) Si can improve the strength of the steel plate, simultaneously Si can be used as a deoxidizer to reduce the content of O, the structure coarsening can be caused when the content of Si is more than 0.35 percent, and the content of Si is controlled to be 0.15 to 0.35 percent.

(3) Mn elements have similar atomic radii with Fe, can be greatly dissolved in a Fe matrix in a solid mode, improve the strength of the steel plate, have small contribution to the strength of the steel plate when the Mn content is lower than 0.6 percent, and can improve the hardenability of the steel plate; however, when the Mn element is too high in percentage by mass, the martensite transformation tendency of the steel plate is weakened in the quenching process, which is not beneficial to quenching and tempering, and the segregation of the Mn element can reduce the corrosion resistance and the welding performance of the steel plate, so that the Mn content is 1.0-1.5%.

(4) P, S element has no benefit to the mechanical property and welding property of the steel plate, but the proper control of P content in the steel, combined action with Cu element, can make the inner rust layer obviously banded, and is beneficial to improving the atmospheric corrosion resistance of the steel plate, so the invention controls P0.02% -0.03%, and S is less than or equal to 0.01%.

(5) Al is a main deoxidizing element in steel, when the content of Al is too low, the deoxidizing effect is poor, and micro-alloy elements such as Ti and the like cannot achieve the purposes of refining grains and improving welding performance due to oxidation; on the contrary, if the Al element is too high, large inclusions are formed, and the content of Als is 0.01-0.03%.

(6) Ni is effective in improving hot workability and improving toughness. Proper addition can obtain lower ductile-brittle transition temperature, and Ni element can improve the marine environment corrosion resistance of the steel plate. In the invention, because a large amount of Cu element is added, in order to avoid high-temperature hot cracking of the steel plate, a large amount of Ni element is added to improve the hot workability of the steel plate, so that the Ni content is 1.5-3.0%.

(7) The Cr element can effectively improve the strength of the steel plate in the steel, and can improve the hardenability of the steel plate for ultrahigh-strength quenched and tempered steel with larger thickness; however, since too high Cr content lowers the impact toughness of the steel sheet, the Cr content is 0.3 to 0.6% in the present invention.

(8) The Mo element can improve the hardenability of the steel plate, can form fine carbide in the steel, can effectively improve the strength of the steel plate, and can also be matched with Ni and Cu to play a certain corrosion resistance role, so that the Mo content is 0.3-0.5 percent in the invention.

(9) The Cu element can effectively improve the corrosion resistance of steel in a reducing atmosphere and also can effectively inhibit the growth and adhesion of microorganisms, and is particularly suitable for the steel for an ocean engineering platform, so the Cu content in the composition design is not lower than 0.5%. However, the addition of Cu element causes the thermoplastic property of the steel to be reduced sharply, so the Cu content should be controlled to 0.5% -1.5% in the present invention.

(10) V is a microalloy element, and the addition of a trace amount of V in the steel can play a role in grain refinement, form V (C, N) particles in a matrix and increase the strength and toughness of the steel plate. Therefore, the V content of the invention is 0.03-0.06%.

(11) Ti element can generate strong precipitation strengthening effect in a matrix, prevent austenite from recrystallizing and growing, refine grains and improve the yield strength of steel. Elements such as Ti, V/N and the like can be separated out near a welding pool and a heat affected zone to form a fine and dispersed second phase of an N-compound, so that the nucleation and growth of ferrite in crystal can be effectively promoted, the growth of original austenite crystal grains can be effectively controlled, and the performance of the welding heat affected zone of the steel plate can be obviously improved. The reasonable design of Ti and V contents can reduce the content of N dissolved in the matrix and improve the comprehensive performance of the steel plate, so the Ti content is controlled to be 0.005-0.02 percent.

(12) The element B can improve the hardenability of the steel plate, a trace amount of the element B can obviously improve the hardenability, and the brittleness of the steel plate is increased and the welding crack tendency is increased when the element B is excessive, so the element B is controlled to be 0.0005-0.001 percent.

(13) The Sb element is a key element in the invention, can obviously improve the corrosion resistance of the steel plate, and can form a compact oxide layer with Cu alloy by adding trace Sb, thereby improving the corrosion resistance of the steel under the reducing atmosphere. However, if the amount of Sb added to the steel is too large, the temper brittleness of the steel is increased, and the toughness and weldability of the steel sheet are adversely affected. Therefore, the Sb content in the invention is 0.005-0.3%.

(14) The Sn element is similar to the Sb element, and the Ni element, the Cu element, the Sb element and the Sn element act together to obviously improve the corrosion resistance of the steel plate in the marine atmospheric environment and seawater, so that the Sb content is 0.005-0.3 percent.

The manufacturing method of the seawater corrosion resistant and biological adhesion resistant EH690 steel plate adopts high cleanliness and alloying smelting, continuous casting, low-temperature heating of casting blanks, rolling, quenching and tempering treatment (namely quenching and tempering treatment), and rapid cooling, and specifically comprises the following steps:

(1) high cleanliness and alloying smelting

And refining the molten steel by a converter, an LF furnace and an RH or VD furnace to further reduce the content of S and nonmetallic inclusions. The obtained weight percentage composition is as follows: 0.09 to 0.12 percent of C, 0.15 to 0.35 percent of Si, 1.0 to 1.5 percent of Mn, 0.02 to 0.03 percent of P, less than or equal to 0.01 percent of S, 0.01 to 0.03 percent of Als, 1.5 to 3.0 percent of Ni, 0.3 to 0.6 percent of Cr, 0.3 to 0.5 percent of Mo, 0.5 to 1.5 percent of Cu, 0.03 to 0.06 percent of V, 0.005 to 0.02 percent of Ti, 0.0005 to 0.001 percent of B, 0.005 to 0.3 percent of Sb, 0.005 to 0.3 percent of Sn, and the balance of Fe and inevitable impurities. And after the casting blank is discharged, stacking in a slow cooling pit and slowly cooling to room temperature.

(2) Rolling process

The steel plate is packaged by a thin plate before entering the furnace, so that the surface oxidation of the steel plate is avoided. And (3) loading the casting blank into a heating furnace at the furnace temperature of 400-500 ℃, and preserving heat for 30-60 min, so that the inner temperature and the outer temperature of the steel blank are kept consistent in a low-temperature stage, and preparation is made for uniform tissue of a high-temperature stage. The temperature rise rate of the casting blank is controlled to be 3-5 ℃/min in the subsequent temperature rise process, so that the condition that the interior of the steel blank is heated unevenly due to the fact that the steel blank is heated too fast is avoided. The soaking temperature is 1100-1150 ℃, the heat preservation is carried out for 100-150 min, and the purpose of low-temperature soaking and heat preservation is to ensure that C/N compounds are fully dissolved and simultaneously avoid high-temperature heat cracking caused by liquefaction of excessive Cu elements in the steel at the grain boundary of the as-cast structure.

The initial rolling temperature of the first stage is 1000-1050 ℃, the initial rolling temperature of the second stage is 900-1000 ℃, the cumulative reduction rate of the rolling of the second stage is 40-60%, and the final rolling temperature is 900-950 ℃. The first stage hot rolling aims at improving the cast structure of a slab, reducing the temperature waiting thickness of a billet and shortening the temperature waiting time of a steel plate; meanwhile, the steel plate is prevented from being rolled at the temperature of more than 1050 ℃, because the Cu element is liquefied at the grain boundary at high temperature to cause high-temperature hot brittleness, and the rolled steel can cause corner cracks and the surface quality of the steel plate to be reduced when the temperature is too high. The second-stage rolling process is designed to increase deformation accumulation in a recrystallization temperature region of 30-50 ℃ above the Ac3 temperature, promote austenite grains to be flattened and refined, achieve the effect of grain refinement, and enable deformation to permeate into the steel plate core during low-temperature rolling at 900-1000 ℃ to improve the mechanical property of the core.

(3) Hardening and tempering process

The quenching temperature is 830-870 ℃, the heat preservation time is 1.0-2.0 min/mm, the tempering temperature is 600-630 ℃, the heat preservation time is 2-3 min/mm, and the cooling rate after tempering is 5-15 ℃/s. The purpose of quenching is to transform the steel plate into a martensite structure after austenitizing, and to prepare the structure for subsequent tempering. The tempering treatment properly reduces the tempering temperature and the heat preservation time, and the rapid cooling after the tempering aims to avoid the tempering brittleness caused by elements such as Sb, Sn, Mo and the like in the steel, simultaneously ensure that the steel plate can be tempered and transformed, and improve the toughness and plasticity.

The yield strength of the steel plate produced by the method is more than or equal to 690MPa, the tensile strength is 770-940 MPa, the Charpy impact energy single value at-40 ℃ is more than or equal to 90J, and the thickness of the steel plate finished product is 30-100 mm. The corrosion rate in seawater is less than 50% of Q345B, the marine atmospheric corrosion rate is less than 70% of Q345B, and the steel plate is resistant to marine organism adhesion.

Has the advantages that:

compared with the prior art, the invention has the following beneficial effects:

(1) by combining the key production technology of the marine steel plate which is matched with Cu, Ni, Mo, Sb and Sn and is resistant to marine environmental corrosion, the corrosion rate of the steel plate in seawater is less than 50 percent of that of Q345B, the marine atmospheric corrosion rate is less than 70 percent of that of Q345B, and the steel plate is resistant to marine organism adhesion.

(2) The innovative alloy component system can ensure that the yield strength of the quenched and tempered steel plate is more than or equal to 690MPa, the tensile strength is 770-940 MPa, and the Charpy impact energy single value at-40 ℃ is more than or equal to 90J.

(3) The thickness of the finished EH690 steel plate product resistant to seawater corrosion and biological adhesion is 30-100 mm.

Drawings

FIG. 1 shows a metallographic structure of a quenched and tempered state at a thickness of 1/4 of a steel sheet and a structure of tempered martensite at a thickness of 1/4 of the steel sheet in example 1;

Detailed Description

The following examples are intended to illustrate the invention in detail, and are intended to be a general description of the invention, and not to limit the invention.

The chemical components of the steel of the embodiment of the invention are shown in table 1, the heating and rolling process of the steel casting blank of the embodiment of the invention is shown in table 2, the quenching and tempering process of the steel of the embodiment of the invention is shown in table 3, the mechanical properties of the steel plate of the embodiment of the invention are shown in table 4, the marine environment corrosion resistance of the steel plate of the embodiment of the invention is shown in table 5, and the biological adhesion resistance of the steel of the embodiment of the invention is shown in table 6.

TABLE 1 chemical composition wt% of steel of examples of the invention

Examples	C	Si	Mn	P	S	Als	Ni	Cr	Mo	Cu	V	Ti	B	Sb	Sn
																1	0.112	0.21	1.01	0.023	0.004	0.022	1.93	0.36	0.33	0.71	0.041	0.014	0.0006	0.009	0.04
2	0.091	0.26	1.33	0.028	0.009	0.022	2.22	0.59	0.39	1.23	0.052	0.018	0.0008	0.01	0.09
																3	0.119	0.35	1.26	0.027	0.007	0.027	2.83	0.43	0.36	1.42	0.060	0.019	0.0009	0.29	0.006
4	0.102	0.29	1.49	0.026	0.009	0.018	2.39	0.40	0.41	1.49	0.047	0.015	0.001	0.07	0.22
																5	0.108	0.32	1.44	0.021	0.01	0.015	2.96	0.31	0.49	1.11	0.031	0.013	0.0005	0.12	0.13
6	0.117	0.30	1.29	0.024	0.01	0.026	2.16	0.33	0.44	0.51	0.057	0.008	0.00061	0.22	0.06
																7	0.096	0.24	1.32	0.02	0.008	0.023	1.51	0.54	0.46	0.96	0.054	0.006	0.0007	0.09	0.29
8	0.104	0.28	1.07	0.027	0.006	0.016	1.78	0.56	0.31	1.08	0.043	0.009	0.00053	0.05	0.17
																9	0.098	0.15	1.14	0.03	0.011	0.03	2.59	0.51	0.35	0.83	0.055	0.013	0.0009	0.26	0.11
10	0.112	0.19	1.21	0.022	0.009	0.019	1.58	0.38	0.42	1.33	0.034	0.016	0.00084	0.17	0.08
																11	0.116	0.18	1.39	0.029	0.009	0.019	1.84	0.48	0.37	0.59	0.059	0.02	0.00052	0.04	0.06
12	0.117	0.31	1.11	0.023	0.009	0.026	2.67	0.46	0.47	0.87	0.031	0.005	0.00092	0.08	0.21

TABLE 2 heating and Rolling Process of Steel casting blank according to the examples of the present invention

TABLE 3 quenching and tempering treatment process for steel of the examples of the present invention

TABLE 4 mechanical Properties of Steel sheets according to examples of the present invention

TABLE 5 Marine Environment Corrosion resistance of Steel plates according to examples of the invention

The full immersion test is referred to as JBT7901 standard, and the salt spray test is referred to as GBT10125 standard. The composition of the comparative steel was 0.17C-0.35Si-1.58Mn-0.04Nb-0.01 Ti.

TABLE 6 Steel of the examples of the invention for resistance to biofouling

Remarking: the numerical values in the table are that the biological attachment area accounts for the percentage of the total area of the steel plate, and the biological attachment area accounts for 23 percent and 45 percent respectively after the steel plate is soaked in seawater for 6 months and 12 months in Q345B.

As can be seen from tables 1-6, the ocean engineering steel produced by the technical scheme of the invention has the yield strength of more than or equal to 690MPa, the tensile strength of 770-940 MPa, the Charpy impact energy single value at-40 ℃ of more than or equal to 90J, and the thickness of a steel plate finished product of 30-100 mm. The corrosion rate in seawater is less than 50% of Q345B, the marine atmospheric corrosion rate is less than 70% of Q345B, and the marine environment corrosion resistance is excellent.

Claims

1. The EH690 steel plate is characterized in that the steel comprises the following chemical components in percentage by mass: 0.09 to 0.12 percent of C, 0.15 to 0.35 percent of Si, 1.0 to 1.5 percent of Mn, 0.02 to 0.03 percent of P, less than or equal to 0.01 percent of S, 0.01 to 0.03 percent of Als, 1.5 to 3.0 percent of Ni, 0.3 to 0.6 percent of Cr, 0.3 to 0.5 percent of Mo, 0.5 to 1.5 percent of Cu, 0.03 to 0.06 percent of V, 0.005 to 0.02 percent of Ti, 0.0005 to 0.001 percent of B, 0.005 to 0.3 percent of Sb, 0.005 to 0.3 percent of Sn, and the balance of Fe and inevitable impurities.

2. The EH690 steel sheet according to claim 1, wherein the yield strength of the steel sheet is 690MPa or more, the tensile strength 770-940 MPa, the Charpy impact energy per unit value at-40 ℃ is 90J or more, the corrosion rate in seawater is 50% or less of Q345B, and the marine atmospheric corrosion rate is 70% or less of Q345B.

3. The EH690 steel sheet of claim 1 or 2, wherein the finished steel sheet has a thickness of 30 to 100 mm.

4. A method of manufacturing an EH690 steel sheet as claimed in claim 1, 2 or 3, which is resistant to corrosion from marine environments and to biofouling, the steel sheet being produced by a process comprising: smelting, continuous casting, heating, rolling and quenching and tempering treatment, which is characterized in that,

(1) smelting: refining the molten steel through a converter, an LF furnace and an RH or VD furnace, and after casting blanks are off-line, stacking in a slow cooling pit and slowly cooling to room temperature;

(2) the heating rolling process comprises the following steps: putting the casting blank into a heating furnace at the furnace temperature of 400-500 ℃, and preserving heat for 30-60 min, wherein the heating rate of the casting blank is controlled to be 3-5 ℃/min, the soaking temperature is 1100-1150 ℃, and the heat preservation is 100-150 min in the subsequent heating process; the initial rolling temperature of the first stage is 1000-1050 ℃, the initial rolling temperature of the second stage is 900-1000 ℃, the cumulative reduction rate of the rolling of the second stage is 40-60%, and the final rolling temperature is 900-950 ℃;

(3) and (3) quenching and tempering: the quenching temperature is 830-870 ℃, the heat preservation time is 1.0-2.0 min/mm, the tempering temperature is 600-630 ℃, the heat preservation time is 2-3 min/mm, and the cooling rate after tempering is 5-15 ℃/s.

5. The method of claim 4, wherein the steel sheet is wrapped with a sheet prior to being introduced into the furnace.