Corrosion-resistant stainless steel pipe and method for manufacturing the same, and stainless steel pipe

Abstract

The application relates to the technical field of stainless steel pipes, in particular to a corrosion-resistant stainless steel pipe and a preparation method thereof and a stainless steel pipe, the stainless steel pipe comprises the following chemical components in percentage by weight: C: 0.11-0.15%, Si: 0.5-0.7%, Mn: 1.2-1.7%, Ta: 0.3-0.8%, Ce: 0.7-1.2%, Cr: 10.1-13.2%, Ni: 4.5-7.5%, Mo 0.5-1%, Cu 3.5-7.5%, S <=0.02%, P <=0.045%, an inclusion phase regulator 0.5-2%, and the balance is Fe element and inevitable impurities; the inclusion phase regulator is prepared by compounding titanium carbide, vanadium carbide and chromium carbide; the stainless steel pipe has the advantages of improving corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of stainless steel pipes, and particularly relates to a corrosion-resistant stainless steel pipe and a preparation method thereof and a stainless steel pipe. BACKGROUND

[0002] Stainless steel is a kind of silver-white alloy steel with excellent corrosion resistance, wear resistance, toughness and workability. Its excellent mechanical properties, good chemical stability and non-toxicity make it widely used in aerospace, ocean, medicine, nuclear energy engineering, petroleum and chemical industry and other fields. In addition, stainless steel is also used for surface decoration of the building industry, household appliances, kitchen equipment, automobile industry and office supplies. Its exquisite natural surface can provide aesthetic and clean feeling. However, the stainless steel pipe material is prone to local corrosion such as pitting corrosion in the environment containing active anions such as chloride ions.

[0003] And the pitting corrosion of stainless steel is almost related to sulfide inclusions. In order to reduce the pitting corrosion of stainless steel, nitric acid or heat treatment and other operations are used in the manufacturing process to form a passivation film on the surface of the stainless steel. The passivation film can effectively protect the substrate from corrosion and oxidation. However, the existing technology cannot make the passivation film uniformly distributed on the surface of the stainless steel. The defects of the passivation film lead to or are prone to expose the active crystals of the stainless steel, and the pitting corrosion phenomenon occurs. Studies have shown that the existence of sulfide inclusions destroys the continuity of the passivation film. The potential difference between the exposed sulfide and the substrate covered by the passivation film forms a primary cell, which induces the occurrence of pitting corrosion. How to improve the compactness and coverage of the passivation film is a difficulty in improving the corrosion resistance of stainless steel. SUMMARY

[0004] In order to improve the corrosion resistance of stainless steel, the present application provides a corrosion-resistant stainless steel pipe and a preparation method thereof and a stainless steel pipe.

[0005] In a first aspect, the present application provides a corrosion-resistant stainless steel pipe, which adopts the following technical scheme:

[0006] A corrosion-resistant stainless steel pipe, which comprises the following chemical components in weight percentage: C: 0.11-0.15%, Si: 0.5-0.7%, Mn: 1.2-1.7%, Ta: 0.3-0.8%, Ce: 0.7-1.2%, Cr: 10.1-13.2%, Ni: 4.5-7.5%, Mo 0.5-1%, Cu 3.5-7.5%, S≤0.02%, P≤0.045%, inclusion phase regulator 0.5-2%, and the balance is Fe element and unavoidable impurities.

[0007] The inclusion phase regulator is prepared by compounding titanium carbide, vanadium carbide and chromium carbide.

[0008] By adopting the above technical scheme, the inclusion phase regulator can adjust the particle size of the sulfur-containing and manganese-containing inclusion phase in the stainless steel material, and by reducing the particle size of the inclusion phase, the influence of the inclusion phase on the coverage of the passivation film generated on the surface of the stainless steel can be reduced; meanwhile, the chromium, nickel, molybdenum, copper, tantalum and cerium contained in the chemical composition can form a passivation film with strong coverage on the surface of the stainless steel material, and the tantalum and cerium have excellent ductility, which can increase the coverage of the passivation film on the surface of the stainless steel material; the simultaneous action of the two can make the passivation film on the surface of the stainless steel material uniform, dense and have strong coverage, thereby greatly improving the corrosion resistance of the stainless steel material.

[0009] Preferably, the weight percentage of the addition of the inclusion phase regulator is 1.2%.

[0010] By adopting the above technical scheme, the addition amount of the inclusion phase regulator can adjust the crystal grain size inside the stainless steel material, and if the addition amount is too small, the adjustment ability of the inclusion phase is small, and if the addition amount is too large, the inclusion phase regulator is easy to agglomerate inside the stainless steel material, and since the inclusion phase regulator is basically not melted during the production of the stainless steel material, the agglomeration is easy to cause pores between the inclusion phase regulator and the system, which can reduce the tensile strength and yield strength of the stainless steel material.

[0011] Preferably, the weight ratio of titanium carbide, vanadium carbide and chromium carbide in the inclusion phase regulator is 5:(1-3):(2-4).

[0012] By adopting the above technical scheme, the inclusion phase regulator requires the joint action of titanium carbide, vanadium carbide and chromium carbide to achieve the technical effect of the present application, and the three have a synergistic effect on the performance of adjusting the particle size of the inclusion phase.

[0013] Preferably, the weight ratio of titanium carbide, vanadium carbide and chromium carbide in the inclusion phase regulator is 5:2:3.

[0014] By adopting the above technical scheme, the proportion of chromium carbide in the inclusion phase regulator has a relatively obvious influence on the corrosion resistance of the stainless steel, and when the weight ratio of titanium carbide, vanadium carbide and chromium carbide is 5:2:3, the adjustment of the particle size of the inclusion phase is optimal.

[0015] Preferably, the particle size of the inclusion phase regulator is 2-6 μm.

[0016] By adopting the above technical scheme, the average particle size of the inclusion phase regulator is an important factor affecting the adjustment of the inclusion phase, and as the particle size gradually increases, the corrosion resistance of the stainless steel material appears a relatively obvious decreasing trend, that is, the particle size increases, and the adjustment ability of the particle size of the inclusion phase decreases, therefore, the particle size should not be more than 6 μm, and considering the production cost, the particle size should not be less than 2 μm.

[0017] The second aspect of the present application provides a preparation method of a corrosion-resistant stainless steel pipe, which adopts the following technical scheme:

[0018] The preparation method of the corrosion-resistant stainless steel pipe comprises the following steps:

[0019] S1, melting pig iron at 1500-1600℃, continuing to heat to 1650-1700℃, then adding silicon powder, chromium powder, nickel powder, molybdenum powder and copper powder, and stirring to obtain a steel liquid;

[0020] S2, blowing oxygen to the steel liquid to remove carbon, and obtaining a low-carbon steel liquid;

[0021] S3, desulfurizing and dephosphorizing the low-carbon steel liquid, so that the sulfur content and the phosphorus content in the low-carbon steel liquid are within a set range;

[0022] S4, continuing to add aluminum powder to the steel liquid obtained in S3 to remove oxygen, and obtaining a deoxidized steel liquid;

[0023] S5, adding carbon powder to the deoxidized steel liquid to adjust and control the carbon content to the required content, then adding an inclusion phase regulator, tantalum diselenide and cerium disilicide, stirring uniformly, and continuing to refine under the protection of inert gas, blowing argon inside, supplementing the composition by detection, so that the chemical composition content is within a limited range, and obtaining a refined steel liquid;

[0024] S6, pouring the refined steel liquid into a mold to form an ingot, and then rolling the ingot into a rough steel material;

[0025] S7, annealing, quenching and tempering the rough steel material to obtain a stainless steel pipe.

[0026] By adopting the above technical scheme, the stainless steel material prepared by the preparation method has excellent mechanical properties and corrosion resistance, and the improvement of the comprehensive performance helps to increase the application potential of the stainless steel material.

[0027] As a preferred, the annealing step of the rough steel material in S7 is as follows:

[0028] The rough steel material is heated in the furnace at a speed of 20-30℃ / min to 1200℃, and then cooled to 600℃ at a speed of 10-20℃ / min, and then cooled with the furnace.

[0029] By adopting the above technical scheme, by increasing the annealing temperature, the passivation film formed on the surface of the stainless steel material after solid solution treatment is enhanced.

[0030] The third aspect of the present application provides a stainless steel pipe, which adopts the following technical scheme:

[0031] A stainless steel pipe made of the corrosion-resistant stainless steel pipe material of any one of claims 1-5.

[0032] In summary, the present application includes at least one of the following beneficial technical effects:

[0033] 1. The inclusion phase regulator can adjust the particle size of the sulfur-containing, manganese-containing and other inclusion phases in the stainless steel material. By reducing the particle size of the inclusion phase, the influence of the inclusion phase on the coverage of the passivation film generated on the surface of the stainless steel can be reduced. At the same time, the chromium, nickel, molybdenum, copper, tantalum and cerium contained in the chemical composition can form a passivation film with strong coverage on the surface of the stainless steel material. Tantalum and cerium have excellent ductility, which can increase the coverage of the passivation film on the surface of the stainless steel material. The simultaneous action of the two can make the passivation film on the surface of the stainless steel material uniform, dense and have strong coverage, thereby greatly improving the corrosion resistance of the stainless steel material.

[0034] 2. The tensile strength of the stainless steel material prepared by the present application is all above 767 MPa, and the maximum can reach 846 MPa. The yield strength is all between 418-457 MPa, and the Vickers hardness is all between 312-343 HV. On the basis of excellent mechanical properties, the corrosion rate is all below 0.141 g / cm2·h, and the minimum can reach 0.012 g / cm2·h. It shows that the stainless steel material prepared by the present application has excellent corrosion resistance, and its mechanical properties also perform excellently. DETAILED DESCRIPTION

[0035] The present application will be further described in detail below in combination with specific contents.

[0036] Raw materials

[0037] The raw materials used in the embodiments of the present application are all ordinary commercially available products.

[0038] Embodiments

[0039] Embodiment 1

[0040] A corrosion-resistant stainless steel pipe material, each chemical component and the weight percentage of each chemical component are as follows: C: 0.13%, Si: 0.6%, Mn: 1.5%, Ta: 0.5%, Ce: 1.0%, Cr: 11.3%, Ni: 6.0%, Mo 0.8%, Cu 5.0%, S≤0.02%, P≤0.045%, inclusion phase regulator 1.2%, and the balance is Fe element and unavoidable impurities;

[0041] The raw materials used for the stainless steel pipe material include pig iron, high-purity carbon powder, high-purity silicon powder, high-purity chromium powder, high-purity nickel powder, high-purity molybdenum powder, high-purity copper powder, tantalum diselenide and cerium disilicide.

[0042] The inclusion phase modifier is prepared by compounding titanium carbide, vanadium carbide and chromium carbide, with a weight ratio of 5:2:3. The average particle size of the inclusion phase modifier is 2 μm.

[0043] The preparation method of corrosion-resistant stainless steel pipes is as follows:

[0044] S1. Pig iron is placed in a converter and melted at 1550°C by heating. The temperature is then increased to 1650°C. Silicon powder, chromium powder, nickel powder, molybdenum powder and copper powder are added and stirred to obtain molten steel.

[0045] S2. Blow oxygen into the converter while rotating it to remove excess carbon until the carbon content is below 0.07%, thus obtaining low-carbon molten steel.

[0046] S3. Add a desulfurizing agent, which is a calcium-based desulfurizing agent, to the low-carbon steel liquid. Control the sulfur content in the low-carbon steel liquid to be less than 0.02% in the rotary converter. Continue to rotate the converter and add a lime-based dephosphorizing agent to control the phosphorus content to be less than 0.045% to obtain desulfurized and dephosphorized steel liquid.

[0047] S4. Continue to add aluminum powder to the desulfurized and dephosphorized steel liquid obtained in S3 for deoxidation, and control the oxygen content to be lower than 0.01% to obtain deoxidized steel liquid.

[0048] S5. Add carbon powder to the deoxidized steel liquid to control the carbon content in the steel liquid to the required level. Then add the inclusion phase regulator, tantalum diselenide and cerium disilicide. After stirring evenly, transfer the steel liquid to the refining furnace under argon protection. Blow argon from the bottom and continue refining. Supplement each chemical component by instrument detection to ensure that the content of each chemical component is within the specified range, and obtain refined steel liquid.

[0049] S6. The refined molten steel is poured into a mold to form an ingot at a pouring temperature of 1600℃. After pouring, it is rolled in 4 passes at a speed of 1.3m / s, with a reduction rate of 10% per pass and a cumulative reduction rate of 40%. The rolled steel is then processed into crude steel material. S7. The crude steel material is then annealed, quenched, and tempered to obtain stainless steel pipe.

[0050] The annealing process is as follows:

[0051] The crude steel material is heated to 1200℃ in the furnace at a rate of 25℃ / min, held at that temperature for 50min, and then cooled to 600℃ at a rate of 15℃ / min, and then cooled in the furnace.

[0052] The quenching steps are as follows:

[0053] The annealed crude steel material is placed in the furnace and heated to 800℃ at a rate of 20℃ / min, and held for 30min, then cooled to 400℃ by water cooling, and then furnace cooled to room temperature;

[0054] The tempering step is as follows:

[0055] High temperature tempering: the quenched crude steel material is placed in the furnace and heated to 600℃ at a rate of 30℃ / min, and held for 3h, then furnace cooled to room temperature;

[0056] Low temperature tempering: after the high temperature tempering is cooled to room temperature, it is heated to 300℃ at a rate of 8℃ / min, and held for 3h, then furnace cooled to room temperature.

[0057] Example 2

[0058] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the inclusion phase modifier is compounded from titanium carbide, vanadium carbide and chromium carbide, and the weight ratio of titanium carbide, vanadium carbide and chromium carbide is 5:2:2, and the remaining steps are the same as Example 1.

[0059] Example 3

[0060] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the inclusion phase modifier is compounded from titanium carbide, vanadium carbide and chromium carbide, and the weight ratio of titanium carbide, vanadium carbide and chromium carbide is 5:2:4, and the remaining steps are the same as Example 1.

[0061] Example 4

[0062] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the weight percentage of the added inclusion phase modifier is 0.5%, and the remaining steps are the same as Example 1.

[0063] Example 5

[0064] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the weight percentage of the added inclusion phase modifier is 2%, and the remaining steps are the same as Example 1.

[0065] Example 6

[0066] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the average particle size of the inclusion phase modifier is 4μm, and the remaining steps are the same as Example 1.

[0067] Example 7

[0068] A corrosion-resistant stainless steel pipe, which differs from Example 1 in that the average particle size of the inclusion phase modifier is 6μm, and the remaining steps are the same as Example 1.

[0069] Example 8

[0070] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that the amount of vanadium carbide added in the inclusion phase modifier is 0, and the remaining steps are the same as in Example 1.

[0071] Example 9

[0072] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that the amount of titanium carbide added in the inclusion phase modifier is 0, and the remaining steps are the same as in Example 1.

[0073] Comparative Example

[0074] Comparative Example 1

[0075] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that, during preparation, no tantalum diselenide and cerium disilicide are added, i.e., the weight percentage of Ta and Ce in the chemical composition of the stainless steel material is 0, and the remaining steps are the same as in Example 1.

[0076] Comparative Example 2

[0077] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that, during preparation, no tantalum diselenide is added, and the weight percentage of cerium disilicide is controlled to 1.5%, and the remaining steps are the same as in Example 1.

[0078] Comparative Example 3

[0079] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that, during preparation, no cerium disilicide is added, and the weight percentage of tantalum diselenide is controlled to 1.5%, and the remaining steps are the same as in Example 1.

[0080] Comparative Example 4

[0081] A corrosion-resistant stainless steel pipe material, which differs from Example 1 in that no inclusion phase modifier is added, and the remaining steps are the same as in Example 1.

[0082] Performance Test Test

[0083] Detection Method / Test Method

[0084] The stainless steel materials were prepared according to the preparation methods in Examples 1-9 and Comparative Examples 1-4, respectively, and then tested according to the following detection methods, and the test results are shown in Table 1.

[0085] Tensile strength and yield strength: tested according to the detection method in GB / T228-2010;

[0086] Vickers hardness: detected by using a HV-1000S type Vickers hardness tester;

[0087] Corrosion rate: after the stainless steel test piece was taken out after being immersed in 5wt% sodium chloride corrosion solution for 48h, it was repeatedly washed by deionized water and dried by cold air, weighed, and the corrosion rate was calculated.

[0088] Test results of examples 1-9 and comparative examples 1-4

[0089]

[0090]

[0091] From the test data of examples 1-9 and comparative examples 1-4, and table 1, it can be seen that the tensile strength of the stainless steel material prepared in the present application is all above 767MPa, and the maximum can reach 846MPa, the yield strength is between 418-457MPa, and the Vickers hardness is between 312-343HV. On the basis of excellent mechanical properties, the corrosion rate is all below 0.141g / cm 2 ·h, and the minimum can reach 0.012g / cm 2 ·h; it shows that the stainless steel material prepared in the present application has excellent corrosion resistance, and its mechanical properties also perform excellently.

[0092] The inclusion phase regulator can adjust the particle size of the sulfur-containing, manganese-containing and other inclusion phases in the stainless steel material. By reducing the particle size of the inclusion phase, the influence of the inclusion phase on the coverage of the passivation film generated on the surface of the stainless steel can be reduced. The test data of examples 1 and comparative example 4 can prove this theoretical speculation.

[0093] From the test data of examples 1-3, it can be seen that the ratio of chromium carbide in the inclusion phase regulator has a relatively obvious influence on the corrosion resistance of the stainless steel. When the weight ratio of titanium carbide, vanadium carbide and chromium carbide is 5:2:3, the adjustment of the particle size of the inclusion phase is best. On the basis of this best ratio, combined with examples 4-5, the best weight percentage of the inclusion phase regulator is 1.2%.

[0094] From examples 1 and examples 6-7, the average particle size of the inclusion phase regulator is an important factor affecting its adjustment of the inclusion phase. As the particle size gradually increases, the corrosion resistance of the stainless steel material appears a relatively obvious decreasing trend, and the particle size thereof should not be more than 6μm.

[0095] It can be seen from the detection data of Example 1 and Examples 8-9 that the inclusion phase regulator of the application requires the joint action of titanium carbide, vanadium carbide and chromium carbide to achieve the technical effect of the application, and the addition proportion of chromium carbide is an important influencing factor affecting corrosion resistance, and the three have a synergistic effect on the particle size of the adjusted inclusion phase.

[0096] The coverage of the passivation film on the surface of the stainless steel by the tantalum diselenide and cerium disilicide is important. It can be seen from the detection data of Example 1 and Comparative Examples 1-3 that both tantalum diselenide and cerium disilicide have strong ductility and can improve the coverage of the passivation film, but the effect of adding both is better than adding either one alone, and the two have a synergistic effect on improving the coverage of the passivation film of the stainless steel.

[0097] The specific embodiments are only an explanation of the application, and are not a limitation of the application, and those skilled in the art can make modifications to the embodiments without creative contribution according to the needs after reading the specification, but as long as the modifications are within the scope of the claims of the application, they are protected by the patent law.

Claims

1. A corrosion resistant stainless steel pipe characterized by: It comprises the following chemical components by weight percentage: C: 0.11-0.15%, Si: 0.5-0.7%, Mn: 1.2-1.7%, Ta: 0.3-0.8%, Ce: 0.7-1.2%, Cr: 10.1-13.2%, Ni: 4.5-7.5%, Mo 0.5-1%, Cu 3.5-7.5%, S ≤ 0.02%, P ≤ 0.045%, inclusion phase regulator 0.5-2%, the balance being Fe element and inevitable impurities; The inclusion phase regulator is prepared by compounding titanium carbide, vanadium carbide and chromium carbide; The weight ratio of titanium carbide, vanadium carbide and chromium carbide in the inclusion phase regulator is 5: (1-3): (2-4); The particle size range of the inclusion phase regulator is 2-6 μm.

2. A corrosion resistant stainless steel pipe according to claim 1, characterized in that: The added weight percentage of the inclusion phase regulator is 1.2%.

3. A corrosion resistant stainless steel pipe according to claim 2, characterized in that: The weight ratio of titanium carbide, vanadium carbide and chromium carbide in the inclusion phase regulator is 5:2:

3.

4. A method of producing the corrosion-resistant stainless steel pipe according to any one of claims 1 to 3, characterized by: It comprises the following steps: S1, smelting pig iron at 1500-1600℃, continuing to heat to 1650-1700℃, then adding silicon powder, chromium powder, nickel powder, molybdenum powder and copper powder, stirring to obtain molten steel; S2, blowing oxygen to the molten steel to remove carbon, obtaining low-carbon molten steel; S3, desulfurizing and dephosphorizing the low-carbon molten steel, so that the sulfur content and phosphorus content in the low-carbon molten steel are within the set range; S4, continuing to add aluminum powder to the molten steel obtained in S3 to remove oxygen, obtaining deoxidized molten steel; S5, adding carbon powder to the deoxidized molten steel to adjust and control the carbon content to the required content, then adding inclusion phase regulator, cerium disilicide and tantalum diselenide, stirring uniformly, then continuing to refine under inert gas protection, blowing argon inside, supplementing the composition by detection, so that the chemical component content is within the limited range, obtaining refined molten steel; S6, pouring the refined molten steel into a mold to form an ingot, then rolling the ingot into a rough steel material; S7, annealing, quenching and tempering the rough steel material to obtain a stainless steel pipe.

5. The method of claim 4, wherein the stainless steel pipe is prepared by the steps of: The annealing process of the rough steel material in S7 is as follows: ​ Raising the temperature of the rough steel material in the furnace to 1200℃ at a rate of 20-30℃ / min, holding for 40-60 min, then lowering the temperature to 600℃ at a rate of 10-20℃ / min, then cooling with the furnace.

6. A stainless steel pipe characterized by: The stainless steel pipe is made of the corrosion-resistant stainless steel pipe material of any one of claims 1-3.

Images