CN109355594B

CN109355594B - Copper-vanadium-cobalt modified stainless steel and processing and heat treatment method thereof

Info

Publication number: CN109355594B
Application number: CN201811576364.9A
Authority: CN
Inventors: 罗丰华; 余罡; 吴子恺; 杨坤; 黄小琴; 黄明初
Original assignee: Foshan Bacon Cell New Material Co ltd
Current assignee: Lufeng New Materials Guangdong Co ltd
Priority date: 2018-12-22
Filing date: 2018-12-22
Publication date: 2022-04-01
Anticipated expiration: 2038-12-22
Also published as: CN109355594A

Abstract

A copper-vanadium-cobalt modified stainless steel and a processing and heat treatment method thereof are disclosed, wherein the mass percentage of alloy elements is as follows: c is less than or equal to 0.03, Ni is 12.0-15.0, Cr is 16.0-18.0, Mo is 2.0-3.0, V is less than or equal to 0.43, Cu is 0.2-0.8, Co is 0.1-0.5, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, wherein V is less than or equal to 4.24 xC +0.3 and the balance is Fe. Carrying out thermal deformation cogging and cold deformation, VC crushing and dispersing, and coarsening crystal grains after high-temperature solution treatment. Oxygen-introducing condition at 80 deg.C and 5 × 10^‑6F^‑0.5mol/L of H₂SO₄The corrosion current density in the electrolyte is 2.19-3.78 mu A/cm²Comparable to surface coated stainless steel bipolar plate material. The method has the characteristics of low hardness and high extension, and is beneficial to the molding of the bipolar plate flow channel.

Description

Copper-vanadium-cobalt modified stainless steel and processing and heat treatment method thereof

Technical Field

The invention belongs to the field of austenitic stainless steel, relates to a method for designing, processing and heat treating components of high-corrosion-resistance austenitic stainless steel, and can be widely applied to the fields of energy, electric power, chemical industry and daily life.

Technical Field

A fuel cell is a device that directly converts chemical energy between hydrogen fuel and an oxidant into electrical energy through an electrode reaction. The system is a fourth generation power generation technology following hydroelectric power generation, thermal power generation and nuclear power generation due to high efficiency, small pollution, short plant building time and good reliability and maintainability. Among the fuel cells, the pem fuel cell is a new fuel cell which is developed later, but is developed most rapidly.

In a fuel cell, the electrically conductive separator plates, which function to support, collect, divide and direct the flow of oxidant and reductant over the surfaces of the electrodes within the cell, are collectively referred to as bipolar plates. Inside the fuel cell stack, the bipolar plate functions and features to separate the oxidant and reductant, so the bipolar plate must have a gas barrier function and cannot be made of porous gas permeable material; has the function of collecting current and must be a good electric conductor. The bipolar plate is subjected to an environment in which both an oxidizing medium, such as oxygen, and a reducing medium, such as hydrogen, are present, so the bipolar plate material must be resistant to corrosion under such conditions and within the potential range at which it operates. The bipolar plates should be good conductors of heat to ensure uniform temperature distribution of the stack and implementation of a heat removal scheme.

The bipolar plate is provided with flow channels for uniformly distributing the reaction gas, i.e. flow fields, on both sides, wherein the flow fields are used for ensuring the uniform distribution of the reaction gas on all positions of the whole electrode, and the bipolar plate also plays a role in supporting the membrane electrode and keeping the stable structure of the cell stack in the fuel cell stack, so that the plate material is required to have certain strength, and the bipolar plate material is light in weight, good in strength and suitable for batch production.

Cost is a major factor that is currently difficult to commercialize, and lower mass-to-volume power is a barrier to automotive power applications. In general, the cost of bipolar plates contributes not only to the overall cost, but also to the weight of the cell reactor. Therefore, it is a goal of bipolar plate development to seek and design inexpensive, lightweight, thin-sheet, with good mechanical properties, high surface and bulk electrical conductivity, low gas permeability, corrosion-resistant materials, and low-cost fabrication techniques.

The bipolar plates widely used at present are graphite plates, metal plates and composite bipolar plates.

The graphite bipolar plate has good corrosion resistance and conductivity, and the contact resistance of the surface is small. Thus, among bipolar plates of various materials, the graphite bipolar plate has the best discharge performance and is often used as a reference system for developing bipolar plates of other new materials. However, graphite has high porosity, low mechanical strength, high brittleness and poor processability, and in order to prevent working gas from permeating through the bipolar plate and meet the mechanical strength design, the thickness of the graphite bipolar plate should be thick, so that the volume and the weight of the graphite bipolar plate are large, and the practical application of the graphite bipolar plate is limited. In particular, the automotive industry, which has great application prospects, requires that it must have a high specific energy by weight and be able to withstand the vibrations of the vehicle during high-speed movements.

The metal material not only has good obdurability, but also has good machining performance, electrical conductivity, thermal conductivity and compactness, and can be used for manufacturing very thin bipolar plates. However, all metals have a disadvantage of poor corrosion resistance, which makes it necessary to improve their properties by various techniques and means.

Comparing the electrochemical behavior of 316L, 317L, 349 and 904L stainless steel in a simulated fuel cell operating environment, the resulting corrosion resistance performance is ranked as: 349>904L >317L >316L, indicating that the higher the chromium content, the stronger the corrosion resistance. The passivation layer formed in the fuel cell environment by the non-surface treated 316L stainless steel will result in increased contact resistance and will not meet the requirements of the bipolar plate material. Therefore, in order to enhance the corrosion resistance of stainless steel, it is necessary to modify or coat the surface thereof with a protective layer.

In order to solve the problems of corrosion and surface passivation of stainless steel and titanium plates as bipolar plate materials in the operation process of a fuel cell, methods such as thermal spraying, screen printing, physical vapor deposition, chemical vapor deposition, electroplating, chemical plating, sputtering and the like are adopted, and the surface treatment not only reduces the contact resistance, but also improves the corrosion resistance of the bipolar plate.

Under the condition of simulating the working environment of the cathode of the battery (0.8V/NHE, 80 ℃, air), constant potential polarization is carried out on 316L stainless steel plated with a nano gold coating with the thickness of 10nm for 24h, and the corrosion current density isLess than 1 muA/cm². It is always in a passivated state in an anodic environment. After the bipolar plate is manufactured by stamping, the contact resistance is 6.3m omega cm under the condition that the assembly force is 0.6MPa²。

Niobium metal is plated on 316L stainless steel by adopting an ion implantation technology under the condition of simulating the working environment of a proton exchange membrane fuel cell (0.5mol/L H)₂SO₄+2ppm HF, 80 ℃ C.), the stainless steel after ion implantation for 2h showed the best performance, with a passivating current density of 6 muA/cm under potentiodynamic test²；

A dense amorphous carbon layer of 3 μm thickness was prepared on 316L stainless steel by closed field unbalanced magnetron sputter ion plating. Under the assembling force of 1.2-2.1 MPa, the contact resistance is 8.3-5.2 m omega cm²And the contact resistance of the graphite is 10.4 to 5.4m omega cm². Under the simulated battery working environment (0.5mol/L, H)₂SO₄+2ppm HF, 80 ℃ C.), and the cathodic passivation current density was 3.56 μ A/cm²。

Among all the metal materials studied, stainless steel materials have been the earliest metal materials for bipolar plates due to their low cost, robustness, and the like. The corrosion resistance of the stainless steel material is determined by the composition and structure of a passivation layer formed on the surface of the stainless steel material, and the composition and structure of the passivation layer are determined by the chemical composition of the stainless steel, so that the proper alloying and structure control of the stainless steel material have certain influence on the corrosion resistance of the stainless steel material.

Disclosure of Invention

The invention aims to provide copper-vanadium-cobalt modified stainless steel and a processing and heat treatment method thereof. The technical scheme adopted for solving the technical problems is that on the basis of the alloy components of the 316L austenitic stainless steel, strong carbide is added to form vanadium (V) and solid solution elements of copper (Cu) and cobalt (Co) at high temperature, which are called 316L-CCV stainless steel for short. The concrete components (mass percent) are as follows: c is less than or equal to 0.03, Ni is 12.0-15.0, Cr is 16.0-18.0, Mo is 2.0-3.0, V is less than or equal to 0.43, Cu is 0.2-0.8, Co is 0.1-0.5, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, wherein V is less than or equal to 4.24 xC +0.3, and the balance is Fe. After the alloy is smelted, the formed VC is fully crushed and dispersed and distributed through thermal deformation cogging and cold deformation treatment, and then a coarse grain austenite structure is obtained through high-temperature solution treatment, so that the alloy has high strength and corrosion resistance.

316L is American grade, corresponding to Chinese stainless steel grade 00Cr17Ni14Mo 2; 316L has wide application in chemical industry due to its excellent corrosion resistance, and 316L also belongs to 18-8 type austenitic stainless steel derived steel grade, and 2-3% of Mo element is added. On the basis of 316L, a plurality of steel grades are derived, for example, 316Ti is derived after a small amount of Ti is added, 316N is derived after a small amount of N is added, and 317L is derived after the contents of Ni and Mo are increased. The performance indexes of the 316L plate are as follows: the yield strength is more than or equal to 177MPa, the tensile strength is more than or equal to 480MPa, the elongation is more than or equal to 40 percent, and the hardness is less than or equal to HV 200.

The 316L stainless steel contains not more than 0.03% of C. C in austenitic stainless steel has a strong solid solution strengthening effect, but C is easily combined with Fe to form cementite Fe₃C, is precipitated in a lamellar manner, so that the corrosion resistance of the stainless steel is difficult to improve. Therefore, the strong carbide forming element V is added into the alloy to form the high-stability VC compound in the spherical particles, so that the actual solid solution content of C in the austenite particles is greatly reduced, and the corrosion resistance of the stainless steel is improved. Since the atomic weight of V is 50.94 and the atomic weight of C is 12.01, the atomic weight ratio of V, C is 4.24, when V is 4.24 XC ≦ 4.24 XC +0.3, such as C content of 0.03%, V content is 0.13% -0.43%, so that the solid solution of C in austenite grains is close to zero, and the excess of V element less than 0.3% forms a solid solution with the matrix, thus having weak strengthening and toughening effects.

Cu is a non-carbide forming element and forms substitutional solid solutions when added to steel. The solid solution strengthening effect of 38-70 MPa can be generated by adding 1.0% of Cu in the steel, the yield strength increment caused by adding the Cu is higher than the increment of the tensile strength, and the yield ratio of the steel can be obviously improved. The Cu ions dissolved out of the surface of the non-induced steel can destroy the protein structure in the bacteria, inhibit the replication of bacterial DNA and the synthesis of related protein/enzyme, destroy the metabolic activity in the bacteria, inactivate the bacteria and cause the bacteria to die. Therefore, 1-3% of Cu is often added into some weather-resistant steel, so that the corrosion resistance of the alloy in the marine environment is improved.

In the invention, a small amount of Cu is added, and the important significance is to make up the deficiency of the C element during high-temperature heat treatment. In austenitic stainless steel, a large amount of Cr and Ni elements are present, and segregation of Cr and Ni elements is also a factor that makes it difficult to further improve the corrosion resistance of stainless steel. Therefore, the heat preservation at high temperature is needed, the diffusion and homogenization of Cr and Ni are promoted, and the existence of C is beneficial to improving the diffusion capability of alloy elements. Because the strong carbide forming element is added, the solid solution content of C in austenite grains is low, which is not beneficial to homogenization, so a small amount of Cu needs to be supplemented, the diffusion capacity is improved, the segregation of Cr and Ni elements is overcome, and the corrosion resistance is further improved.

Co is a non-carbide element, is a ferrite-forming element, and forms a continuous solid solution with ferrite. Cobalt can reduce the hardenability of steel, and cobalt can increase the diffusion speed of carbon in austenite, so that the phase transformation process is accelerated, and the hardenability of steel is reduced. Cobalt not only accelerates the high temperature transformation process of the steel (austenite → pearlite), but also affects the medium temperature transformation process (austenite → bainite). Co is added into austenitic stainless steel in a small amount, phase change is not caused, and because the atomic radius of the cobalt is 1.26 and is slightly smaller than that of iron, the atomic radius of the cobalt is 1.27, Co atoms which are dissolved into an Fe matrix can form a tensile stress field, and the hardness of the stainless steel is reduced.

The bipolar plates have flow channels on both sides, so-called flow fields, which allow a uniform distribution of the reaction gases. These runners are obtained by roll forming, and the bipolar plate material has low hardness, and can reduce springback and stress concentration generated during rolling. Co reduces the hardness of the stainless steel, and is beneficial to the processing of a flow field.

The preparation method of the 316L-CCV stainless steel comprises the following main steps:

(1) smelting and casting of 316L-CCV stainless steel

The method comprises the steps of selecting electrician pure iron, metal chromium sheets, metal nickel plates, stainless steel waste, metal molybdenum, pure copper blocks, pure cobalt sheets, ferrovanadium or metal vanadium and graphite blocks as raw materials, carrying out electric arc melting or induction melting, and then casting into alloy cast ingots.

Because the alloy is added with elements such as Cu, V, Co and the like, the stainless steel industrial production methods such as a converter vacuum oxygen blowing decarburization method and the like are not suitable, and the alloy can be prepared only by adopting an electric arc melting method or an induction melting method. During smelting, vacuum or argon protection is adopted to avoid oxidation.

The stainless steel waste is mainly austenitic stainless steel waste with high nickel, high chromium and high molybdenum content such as 316 and 316L, and then raw materials such as electrician pure iron, metal chromium sheets, metal nickel plates, metal molybdenum, pure copper blocks, pure cobalt sheets, ferrovanadium or metal vanadium and graphite blocks are used for preparing alloy in the composition range of the 316L-CCV stainless steel, main elements such as C, Cr, Ni, Cu, V, Mo and Co in the alloy are controlled, and impurity elements such as Mn, Si, P and S are ensured through the purity of the raw materials.

The temperature of a molten pool is maintained to be 1700 +/-20 ℃ during smelting; and (3) before casting, keeping the molten steel stationary for 5-10 minutes, and casting the molten steel at 1550 +/-50 ℃ under vacuum or argon protection. And casting into square ingots or round ingots according to the specification requirements of subsequent products.

(2) Hot rolling cogging

The plate is hot-rolled and cogging by adopting a flat roller mill, the hot-rolling scheme is that a casting blank is heated to 1280 +/-10 ℃, the temperature is kept for 3-5 hours, then the casting blank is discharged for rolling, the hot-rolling starting temperature is 1180 +/-20 ℃, and the final rolling temperature is more than or equal to 950 ℃. The total lower amount of the hot rolled plate is more than or equal to 60 percent.

The cast ingot can be opened by hot forging, hole rolling or universal rolling.

(3) Cold rolling deformation

The plate is deformed by cold rolling, and the total cold rolling reduction is more than or equal to 80 percent.

The purpose of hot rolling and cold rolling is to sufficiently crush carbides in the alloy; the large cold rolling deformation is beneficial to ensuring that a coarse and large crystal structure is formed during subsequent heating treatment.

The pipe, the bar, the wire and the section bar can be subjected to cold deformation by adopting a reciprocating pipe rolling, hole pattern rolling, universal rolling or drawing method to obtain the required size and specification of the product; the stainless steel parts needed by the mechanical industry can also be obtained by adopting hot deformation cogging raw materials and then cold stamping.

(4) High temperature heat treatment

After cold deformation, annealing treatment is carried out at 1085 +/-30 ℃, the heat preservation time is 30-120 minutes, and vacuum or inert gases such as argon, nitrogen, helium and the like are adopted for protection during heating; after annealing, the alloy is rapidly cooled by adopting gas media such as water, oil or argon, nitrogen, helium and the like.

The purpose of the high temperature hold is to form coarse recrystallized grains, so that the broken spherical carbides are transferred from the grain boundaries to the interior of the coarse recrystallized grains, thereby reducing the grain boundary corrosion tendency. The rapid cooling can avoid grain boundary precipitation of a small amount of residual carbide, and the main purpose is to control segregation of the Cu element, improve the solid solubility of the Cu element and obtain high strength and hardness.

According to the size of the product and the requirement for surface quality, a cooling medium is selected, when the size of the product is larger, liquid media such as water, oil and the like can be adopted to realize rapid cooling, and gas media such as argon, nitrogen, helium and the like can be adopted to rapidly cool the thin plate or the small part.

The high-temperature heat treatment method can be implemented by vacuum heating-gas quenching, continuous heating-water cooling quenching, continuous heating-high-pressure gas quenching, gas shielded heating-water (oil) quenching and the like. And straightening or shaping after annealing, wherein the deformation of the straightening or shaping treatment is less than 2%.

The 316L-CCV stainless steel subjected to high-temperature heat treatment adopts a Tafel (Tafel) line extrapolation method to obtain corrosion current which is used as a basis for comparing the corrosion resistance of the alloy, and the hardness and the tensile mechanical property of the alloy are measured.

Tafel (Tafel) line extrapolation is a method to determine corrosion rate. The method is to make metal sample into electrode and immerse it in corrosive medium, measure the steady volt-ampere (E-I) data, and make log I-E picture, and extend the straight line part of the cathode and anode polarization curve. The obtained intersection points are corresponding to logI_corFrom corrosion current I_corDivided by the area S of the sample measured accurately in advance₀Thus obtaining the corrosion rate. The method is fast and time-saving, and is suitable for measuring the uniform corrosion of metal.

Under the condition of simulating the working environment of the proton exchange membrane fuel cell,therefore 80 ℃ was chosen as the test temperature for comparison of corrosion performance. The specific measurement conditions of the corrosion rate are: at 1cm²Stainless steel is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum sheet is used as an auxiliary electrode; containing 5X 10^-6F^-0.5mol/L of H₂SO₄Heating the electrolyte to 80 ℃ by using a water bath box, and introducing oxygen into the electrolyte at a flow rate of 20 ml/min; the samples were subjected to a linear potential scan at a scan rate of 2 mV/s. The measurement is completed by using the function of a constant potential instrument of an electrochemical constant potential tester or a constant potential instrument of an electrochemical workstation, and the measured polarization curve is subjected to Tafel (Tafel) fitting by using the test software of the instrument to obtain the corrosion current. The corrosion current of 316L stainless steel measured by the method at room temperature is 32 mu A/cm²1300 muA/cm at 80 DEG C²。

The invention is mainly characterized in that on the basis of 316L stainless steel alloy, a strong carbide forming element V is added, and the solid solubility of actual C in austenite grains is reduced; the Cu element is added to improve the high-temperature diffusion capacity, and the segregation of Cr and Ni elements is avoided; co element is added to reduce the hardness of the stainless steel; and then the carbide is crushed through thermal deformation and cold deformation, and coarse grains are formed through high-temperature quenching treatment, so that the alloy is softened and has excellent corrosion resistance. The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄The electrolyte is 2.19 to 3.78A/cm²The corrosion rate is greatly reduced and is equivalent to that of the stainless steel bipolar plate treated by the surface coating. The rigidity is 159-172 HV1, the yield strength is 162-172 MPa, the tensile strength is 519-537 MPa, the elongation is 41-47%, and the composite material has the characteristics of low rigidity and high elongation, and is particularly beneficial to the forming treatment of bipolar plate runners.

Drawings

FIG. 1 metallographic structure of the invention example 1;

FIG. 2 polarization graph of inventive example 2;

FIG. 3 tensile mechanical property graph of inventive example 3.

Detailed Description

The various melting and casting methods of the present invention are not limited by the following examples, and any modifications and variations within the scope of the claims of the present invention are within the scope of the present invention.

The alloy is prepared from electrician pure iron, chromium metal sheets, nickel metal plates, molybdenum metal, stainless steel waste, pure copper blocks, pure cobalt sheets, ferrovanadium or vanadium metal and graphite blocks as raw materials within the component range required by the invention.

The stainless steel and its parts prepared by the method can be processed by mechanical processing, polishing and corresponding chemical cleaning and polishing treatment for shape, dimension and surface quality, and the invention is not limited in detail.

Example 1

Selecting electrician pure iron, a metal chromium sheet, a metal nickel plate, metal molybdenum, 316 stainless steel waste, a pure copper block, a pure cobalt sheet and metal vanadium as raw materials, wherein the prepared stainless steel comprises the following components: c is 0.03, Ni is 12.0, Cr is 16.0, Mo is 2.0, V is 0.12, Cu is 0.2, Co is 0.1, Mn is 1.2, Si is 0.8, P is 0.035, S is 0.030, and the balance is Fe.

After weighing corresponding raw materials according to the component requirement, performing argon protection arc melting, and keeping the temperature of a molten pool at 1720 ℃ during melting; before casting, the molten steel is kept still for 10 minutes, and the molten steel is cast at 1600 ℃ under the protection of argon.

The plate is hot rolled and cogging by adopting a flat roller mill, the hot rolling scheme is that a casting blank is heated to 1290 ℃, the temperature is preserved for 5 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling starting temperature is 1190 ℃, and the final rolling temperature is 950 ℃. The total amount of the plate hot rolled is 60%.

The plate is deformed by cold rolling, and the total reduction of the cold rolling is 80 percent.

Annealing the plate at 1115 ℃, keeping the temperature for 30 minutes, and heating under the protection of argon; and after annealing, cooling by water quenching.

FIG. 1 shows a metallographic structure of a longitudinal section of a plate, wherein crystal grains of the metallographic structure are coarse, a small amount of annealing twin crystals are formed, granular fine carbides are distributed in the crystal grains, and the number of the granular fine carbides is small. The fine carbides will fall off preferentially during corrosion, and the remaining surface has uniform texture and strong corrosion resistance.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄2.19 mu A/cm in the electrolyte². The alloy had a hardness of 159HV1, a yield strength of 172MPa, a tensile strength of 527MPa, and an elongation of 45%.

Example 2

Selecting 316L stainless steel waste, metal molybdenum, a pure copper block, a pure cobalt sheet and ferrovanadium as raw materials, wherein the prepared stainless steel comprises the following components: c0.014, Ni 13.0, Cr 16.8, Mo 2.1, V0.25, Cu 0.3, Co 0.2, Mn 1.2, Si 0.7, P0.035, S0.030, and the balance Fe.

Weighing corresponding raw materials according to the component requirement, and then carrying out vacuum induction smelting, wherein the temperature of a molten pool is kept at 1680 ℃ during smelting; before casting, the molten steel is kept still for 5 minutes, and the molten steel is cast in vacuum at 1500 ℃.

The plate is hot rolled and cogging by adopting a flat roller mill, wherein the hot rolling scheme is that a casting blank is heated to 1270 ℃, the temperature is kept for 5 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling starting temperature is 1160 ℃, and the final rolling temperature is 1000 ℃. The total plate hot rolling reduction is 65%.

The plate is deformed by cold rolling, and the total cold rolling reduction is 85%.

The plate is kept warm for 120 minutes at 1055 ℃, and helium gas quenching is adopted after vacuum annealing.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄The electrolyte content is 3.58 mu A/cm²The polarization curve is shown in FIG. 2. The alloy had a hardness of 172HV1, a yield strength of 171MPa, a tensile strength of 519MPa, and an elongation of 42%.

Example 3

The method comprises the following steps of selecting electrician pure iron, a metal chromium sheet, a metal nickel plate, metal molybdenum, a pure copper block, a pure cobalt sheet, ferrovanadium and a graphite block as raw materials, and preparing the stainless steel with the following components: 0.025% for C, 15.0% for Ni, 18.0% for Cr, 3.0% for Mo, 0.25% for V, 0.4% for Cu, 0.3% for Co, 0.8% for Mn, 0.5% for Si, 0.035% for P, 0.030% for S, and the balance Fe.

Weighing corresponding raw materials according to the component requirement, and then carrying out induction smelting under the protection of argon, wherein the temperature of a molten pool is maintained at 1700 ℃ during smelting; before casting, the molten steel is kept still for 7 minutes, and the molten steel is cast at 1550 ℃ under the protection of argon.

The plate is hot rolled and cogging by adopting a flat roller mill, the hot rolling scheme is that a casting blank is heated to 1280 ℃, the temperature is preserved for 4 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling starting temperature is 1180 ℃, and the final rolling temperature is 980 ℃. The total plate hot rolling reduction is 70%.

The plate is deformed by cold rolling, and the total cold rolling reduction is 82%.

Annealing the plate at 1100 ℃, keeping the temperature for 60 minutes, and adopting nitrogen protection; annealing in a continuous annealing furnace, and rapidly cooling with high-pressure nitrogen after annealing.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄The electrolyte content is 3.78 mu A/cm². The hardness of the alloy is 167HV1, the yield strength is 162MPa, the tensile strength is 537MPa, the elongation is 41%, and the tensile mechanical property curve is shown in figure 3.

Example 4

Selecting 316L stainless steel waste, pure copper blocks, pure cobalt sheets, metal vanadium and graphite blocks as raw materials, wherein the prepared stainless steel comprises the following components: c ═ 0.016, Ni ═ 12.2, Cr ═ 16.5, Mo ═ 2.8, V ═ 0.35, Cu ═ 0.5, Co ═ 0.4, Mn ═ 1.3, Si ═ 0.3, P ≦ 0.035, S ≦ 0.030, and the balance Fe.

Weighing corresponding raw materials according to the component requirement, and then carrying out vacuum induction smelting, wherein the temperature of a molten pool is kept at 1690 ℃ during smelting; before casting, the molten steel is kept still for 8 minutes, and the molten steel is cast in vacuum at 1550 ℃. And casting to form a square ingot.

The ingot casting adopts hot rolling cogging, and the hot rolling scheme is that a casting blank is heated to 1290 ℃, the temperature is kept for 3 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling initial forging temperature is 1200 ℃, the final rolling temperature is 1020 ℃, and the total hot rolling reduction is 68%.

Annealing treatment is carried out at 1105 ℃ after cold rolling, the heat preservation time is 45 minutes, and vacuum annealing and oil quenching are adopted during heating.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄The electrolyte content is 3.24 muA/cm². The alloy had a hardness of 163HV1, a yield strength of 169MPa, a tensile strength of 525MPa, and an elongation of 45%.

Example 5

The method comprises the following steps of selecting electrician pure iron, a metal chromium sheet, a metal nickel plate, metal molybdenum, a pure copper block, a pure cobalt sheet, ferrovanadium and a graphite block as raw materials, and preparing the stainless steel with the following components: c is 0.027, Ni is 14.2, Cr is 16.3, Mo is 2.4, V is 0.39, Cu is 0.7, Co is 0.5, Mn is 0.6, Si is 0.3, P is less than or equal to 0.035, S is less than or equal to 0.030, and Fe is the remainder.

After weighing corresponding raw materials according to the component requirement, carrying out arc melting in an argon atmosphere, and keeping the temperature of a molten pool at 1700 ℃ during melting; before casting, the molten steel is kept still for 6 minutes, and the molten steel is cast at 1580 ℃ under the protection of argon. The plate is hot rolled and cogging by adopting a flat roller mill, wherein the hot rolling scheme is that a casting blank is heated to 1280 ℃, the temperature is preserved for 4 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling starting temperature is 1180 ℃, and the final rolling temperature is 1000 ℃. The total plate hot rolling reduction is 65%.

Annealing the plate at 1100 ℃, keeping the temperature for 90 minutes, heating and keeping the temperature by adopting vacuum protection, and quenching the plate by adopting high-pressure argon after the heat preservation is finished.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄The electrolyte content is 2.74 mu A/cm². The alloy had a hardness of 165HV1, a yield strength of 163MPa, a tensile strength of 520MPa, and an elongation of 47%.

Example 6

Selecting 316L stainless steel waste, pure copper blocks, pure cobalt sheets, ferrovanadium and graphite blocks as raw materials, wherein the prepared stainless steel comprises the following components: c is 0.03, Ni is 14.2, Cr is 17.5, Mo is 2.1, V is 0.43, Cu is 0.8, Co is 0.3, Mn is 1.2, Si is 0.6, P is 0.035, S is 0.030, and the balance is Fe.

Weighing corresponding raw materials according to the component requirement, and then carrying out vacuum induction smelting, wherein the temperature of a molten pool is kept at 1710 ℃; before casting, the molten steel is kept still for 8 minutes, and the molten steel is cast in vacuum at 1580 ℃.

The plate is hot rolled and cogging by adopting a flat roller mill, the hot rolling scheme is that a casting blank is heated to 1290 ℃, the temperature is kept for 4.5 hours, then the casting blank is discharged and rolled, the hot rolling starting temperature is 1180 ℃, and the final rolling temperature is 1050 ℃. The total amount of the plate hot rolled is 80%.

The plate is deformed by cold rolling, and the total reduction of the cold rolling is 88 percent.

Annealing the plate at 1065 ℃ for 85 minutes, and adopting nitrogen gas protection and oil cooling.

The corrosion current of the 316L-CCV alloy after high-temperature quenching treatment is 5 multiplied by 10 at 80 ℃ under the condition of oxygen introduction^-6F^-0.5mol/L of H₂SO₄2.85 muA/cm in the electrolyte². The alloy had a hardness of 169HV1, a yield strength of 169MPa, a tensile strength of 531MPa, and an elongation of 41%.

The properties of the 316L-CCV alloy obtained in the preparation process of the above example were measured as follows:

1. the hardness of the alloy material of the example was measured by using an HVS-50 Vickers hardness tester under a load of 1Kg, and the average value was taken after beating 5 points and is shown in Table 1.

2. An electronic universal tester is adopted to carry out a tensile test on the example alloy material, a rectangular sample with the nominal section size of 1-2 multiplied by 5 multiplied by 30mm is taken, and the average values of the tensile strength, the yield strength and the elongation of 3 samples treated in the same way are listed in Table 1

3. The corrosion current measurements were carried out on the example alloys using the electrochemical workstation CHI660D under the following test conditions: the area of the corroded surface is 1cm²The example alloy is a working electrode, a saturated calomel electrode is a reference electrode, and a platinum sheet is an auxiliary electrode; containing 5X 10^-6F^-0.5mol/L of H₂SO₄Heating the electrolyte to 80 ℃ by using a water bath box, and introducing oxygen into the electrolyte at a flow rate of 20 ml/min; the samples were subjected to a linear potential scan at a scan rate of 2 mV/s. After 3 samples were measured, the average value was obtained, and the columnIn table 1.

Table 1 composition and corrosion current, hardness and tensile properties of the examples

The compositions of Mn, Si, P, S and the like of the examples in Table 1 meet the alloy invention requirements, and Fe is the balance and is not listed in Table 1.

Claims

1. A copper vanadium cobalt modified stainless steel is characterized in that: the alloy comprises the following elements in percentage by mass: c is less than or equal to 0.03, Ni is 12.0-15.0, Cr is 16.0-18.0, Mo is 2.0-3.0, V is less than or equal to 0.43, Cu is 0.2-0.8, Co is 0.1-0.5, Mn is less than or equal to 2.0, Si is less than or equal to 1.0, P is less than or equal to 0.035, S is less than or equal to 0.030, wherein V is less than or equal to 4.24 xC +0.3 and the balance is Fe; the processing and heat treatment method of the copper-vanadium-cobalt modified stainless steel comprises the following steps:

(1) smelting and casting stainless steel, selecting electrician pure iron, a metal chromium sheet, a metal nickel plate, stainless steel waste, metal molybdenum, a pure copper block, a pure cobalt sheet, ferrovanadium or metal vanadium and a graphite block as raw materials according to the mass percentage of each element required by alloy, and casting the raw materials into an alloy ingot after electric arc smelting or induction smelting; the temperature of a molten pool is maintained to be 1700 +/-20 ℃ during smelting; before casting, the molten steel is kept still for 5-10 minutes, and the molten steel is cast at 1550 +/-50 ℃ under the protection of vacuum or argon to be cast into square ingots or round ingots;

(2) hot rolling and cogging a hot-rolled cogging plate by adopting a flat roll mill, wherein the hot rolling scheme is that a casting blank is heated to 1280 +/-10 ℃, the temperature is kept for 3-5 hours, then the casting blank is discharged from a furnace for rolling, the hot rolling starting temperature is 1180 +/-20 ℃, and the final rolling temperature is more than or equal to 950 ℃; the total reduction of the hot rolling of the plate is more than or equal to 60 percent; pipes, rods, wires, profiles and cold punching parts, and the ingot casting can be performed by hot forging, hole-pattern rolling or universal rolling for cogging;

(3) the cold-rolled deformation plate adopts cold-rolled deformation, and the total cold-rolled reduction is more than or equal to 80 percent; cold deformation is carried out on the pipe, the rod, the wire and the section by adopting a reciprocating pipe rolling, hole pattern rolling, universal rolling or drawing method to obtain the required size and specification of the product;

(4) after the high-temperature heat treatment and cold deformation, carrying out annealing treatment at 1085 +/-30 ℃ by using vacuum heating-gas quenching, continuous heating-water cooling quenching, continuous heating-high-pressure gas quenching, gas shielded heating-water quenching or gas shielded heating-oil quenching, wherein the heat preservation time is 30-120 minutes, and the heating is carried out under vacuum or shielded gas; after annealing, the steel is rapidly cooled by water, oil or protective gas medium.

2. The copper vanadium cobalt modified stainless steel of claim 1, wherein: the protective gas is: argon, nitrogen or helium.

3. The copper vanadium cobalt modified stainless steel of claim 1, wherein: and straightening or shaping after annealing, wherein the deformation of the straightening or shaping treatment is less than 2%.