High-toughness antibacterial stainless steel composite pipe and preparation method thereof

Abstract

The invention relates to the technical field of composite pipes, and provides a high-toughness antibacterial stainless steel composite pipe and a preparation method thereof. The stainless steel composite pipe is formed by compositing an inner layer pipe and an outer layer pipe, and the outer layer pipe is composed of, by weight, 0.16%-0.22% of C, 0.45%-0.65% of Si, 1.5%-3.2% of Cu, 0.14%-0.4% of Al, 0.15%-0.25% of Mn, 0.08%-0.16% of V, 0.05%-0.18% of B, 0.12%-0.2% of Mo, 0.34%-0.48% of Ni, 0.05%-0.15% of La, 0.15%-0.55% of Cr, smaller than or equal to 0.023% of P, smaller than or equal to 0.01% of S, smaller than or equal to 0.008% of N and the balance iron and inevitable impurities. By means of the technical scheme, the problem that stainless steel composite pipes in the related technology are poor in impact toughness is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite pipes, and specifically, to a high-toughness antibacterial stainless steel composite pipe and a preparation method thereof. Background Art

[0002] Stainless steel composite pipes are prepared by a special process to composite a steel pipe with another pipe of the same or different materials, so that they have the dual advantages of both the steel pipe and the other pipe. Due to their unique structural and performance advantages, stainless steel composite pipes are widely used in many fields such as food processing pipelines, pharmaceutical production pipelines, water supply pipelines, and urban drainage pipelines. Stainless steel composite pipes combine the performance advantages of steel pipes and other metal pipes. However, the current stainless steel composite pipes have defects in toughness because there are certain differences in the material properties of the inner and outer layer pipes and they cannot be well matched, especially the influence of the outer pipe is greater. Therefore, it is of great significance to develop a stainless steel composite pipe that can improve the impact toughness of the stainless steel composite pipe, which can extend the service life of the composite pipe and reduce its maintenance cost. Summary of the Invention

[0003] The present invention provides a high-toughness antibacterial stainless steel composite pipe and a preparation method thereof, which solve the problem of poor impact toughness of stainless steel composite pipes in related technologies.

[0004] The technical solution of the present invention is as follows: The present invention provides a high-toughness antibacterial stainless steel composite pipe, which is composed of an inner layer pipe and an outer layer pipe. The outer layer pipe is composed of the following components by weight percentage: C 0.16% - 0.22%, Si 0.45% - 0.65%, Cu 1.5% - 3.2%, Al 0.14% - 0.4%, Mn 0.15% - 0.25%, V 0.08% - 0.16%, B 0.05% - 0.18%, Mo 0.12% - 0.2%, Ni 0.34% - 0.48%, La 0.05% - 0.15%, Cr 0.15% - 0.55%, P≤0.023%, S≤0.01%, N≤0.008%, and the balance is iron and unavoidable impurities.

[0005] As a further technical solution, the weight percentages of Al, B, and La satisfy the following relationship: 1 ≤ Al / (B + La) ≤ 1.5.

[0006] When the weight percentages of Al, B, and La satisfy the relationship of 1 ≤ Al / (B + La) ≤ 1.5, the impact toughness of the stainless steel composite pipe can be further improved.

[0007] As a further technical solution, the weight ratio of B to La is 3:1.

[0008] As a further technical solution, the inner layer tube is composed of the following components by weight percentage: Ni 0.45% - 0.55%, Mo 0.1% - 0.2%, W 0.25% - 0.3%, Fe 0.16% - 0.26%, Ag 0.03% - 0.09%, V 0.1% - 0.26%, Y 0.015% - 0.085%, P ≤ 0.015%, S ≤ 0.01%, and the balance is copper and inevitable impurities.

[0009] The present invention also provides a method for preparing the high - toughness antibacterial stainless - steel composite tube, comprising the following steps: S1. Weigh and mix the components of the outer layer tube as described above, melt, refine, continuously cast, pierce, heat, roll, and perform heat treatment to obtain the outer layer tube; S2. Weigh and mix the components of the inner layer tube as described above, melt, refine, continuously cast, pierce, roll, and perform heat treatment to obtain the inner layer tube; S3. Insert the inner layer tube into the outer layer tube until the bottom, seal one end of the outer layer tube, evacuate, and perform heat treatment to obtain the stainless - steel composite tube.

[0010] As a further technical solution, in step S1, during the heating process, the heating atmosphere is a mixed atmosphere of H2 - CO - CH4.

[0011] As a further technical solution, the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 4:45 - 50:2.

[0012] In the present invention, when the outer layer tube is heated in a mixed atmosphere of H2 - CO - CH4, by adjusting the volume of each gas component in the mixed atmosphere so that the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 4:45 - 50:2, the carburizing speed and depth can be balanced, the carburized layer structure can be made more uniform, thereby improving the wear resistance of the outer layer tube, and ultimately improving the overall wear resistance of the stainless - steel composite tube.

[0013] As a further technical solution, in step S1, during the heat treatment, after quenching at 700 - 910°C for 2 - 3 h, cool to room temperature; then perform tempering at 400 - 650°C for 1 - 2 h and cool to room temperature; In step S2, during the heat treatment, after quenching at 750 - 860°C for 2 - 3 h, cool to room temperature; then perform tempering at 450 - 600°C for 1 - 2 h and cool to room temperature.

[0014] As a further technical solution, in step S3, when evacuating the air, evacuate to a vacuum degree of 0.1~0.5 Pa.

[0015] As a further technical solution, when welding and sealing, the welding current is 150~250 mA and the welding speed is 175~195 mm / s.

[0016] As a further technical solution, when performing the heat treatment, the temperature is 920~980 °C and the pressure is 0.8~1.2 MPa.

[0017] The temperature of the heat treatment is in the range of 920~980 °C. The inner layer tube and the outer layer tube are effectively combined within this temperature range, which can ensure the integrity and stability of the composite tube structure.

[0018] The working principle and beneficial effects of the present invention are as follows: In the present invention, by optimizing the component composition of the outer layer tube of the stainless steel composite tube, with the effective cooperation of each component, the outer layer tube has good impact toughness. Among them, three elements, Al, B, and La, are introduced. Al, B, and La have a synergistic effect. Through the synergistic effect of the three, the impurity particles in the outer layer tube material can be refined and reduced, making the internal structure of the outer layer tube uniform and dense, significantly improving the impact toughness of the outer layer tube of the stainless steel composite tube, and thus significantly improving the overall impact toughness of the stainless steel composite tube. Specific Embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0020] Embodiment 1 A high-toughness antibacterial stainless steel composite tube is composed of a composite of an inner layer tube and an outer layer tube. The outer layer tube is composed of the following components by weight percentage: C 0.16%, Si 0.45%, Cu 1.5%, Al 0.14%, Mn 0.15%, V 0.08%, B 0.05%, Mo 0.12%, Ni 0.34%, La 0.05%, Cr 0.15%, P 0.003%, S 0.002%, N 0.002%, and the balance is iron and inevitable impurities; The inner layer tube is composed of the following components by weight percentage: Ni 0.45%, Mo 0.1%, W 0.25%, Fe 0.16%, Ag 0.03%, V 0.1%, Y 0.015%, P 0.003%, S 0.002%, the balance being copper and unavoidable impurities; A method for preparing a high-toughness antibacterial stainless steel composite pipe, comprising the following steps: S1. Weigh the components of the outer pipe, melt, refine, continuously cast, pierce, heat in a H2-CO-CH4 mixed atmosphere with a volume ratio of 2:20:1, roll, perform quenching treatment at 700 °C for 3 h, cool to room temperature, perform tempering treatment at 400 °C for 2 h, and then cool to room temperature to obtain the outer pipe; S2. Weigh the components of the inner pipe according to the weight parts, melt, refine, continuously cast, pierce, roll, perform quenching treatment at 750 °C for 3 h, cool to room temperature, perform tempering treatment at 450 °C for 2 h, and then cool to room temperature to obtain the inner pipe; S3. Insert the inner pipe into the outer pipe until the bottom, seal one end of the outer pipe with a welding current of 150 mA at a welding speed of 175 mm / s, evacuate to a vacuum degree of 0.1 Pa, and perform heat treatment at 920 °C and 0.8 Pa to obtain the stainless steel composite pipe.

[0021] Example 2 A high-toughness antibacterial stainless steel composite pipe, which is composed of a composite of an inner pipe and an outer pipe. The outer pipe is composed of the following components in weight percentage: C 0.18%, Si 0.5%, Cu 2.3%, Al 0.22%, Mn 0.2%, V 0.12%, B 0.168%, Mo 0.16%, Ni 0.41%, La 0.112%, Cr 0.35%, P 0.01%, S 0.006%, N 0.006%, the balance being iron and unavoidable impurities; The inner pipe is composed of the following components in weight percentage: Ni 0.5%, Mo 0.15%, W 0.28%, Fe 0.2%, Ag 0.06%, V 0.18%, Y 0.045%, P 0.008%, S 0.007%, the balance being copper and unavoidable impurities; A method for preparing a high-toughness antibacterial stainless steel composite pipe, comprising the following steps: S1. Weigh the components of the outer pipe, melt, refine, continuously cast, pierce, heat in a H2-CO-CH4 mixed atmosphere with a volume ratio of 2:20:1, roll, perform quenching treatment at 800 °C for 2.5 h, cool to room temperature, perform tempering treatment at 525 °C for 1.5 h, and then cool to room temperature to obtain the outer pipe; S2. Weigh and mix the components of the inner tube, melt, refine, continuously cast, pierce, roll, perform quenching treatment at 800 °C for 2.5 h, then cool to room temperature, perform tempering treatment at 520 °C for 1.5 h, and then cool to room temperature to obtain the inner tube; S3. Insert the inner tube into the outer tube until the bottom, seal one end of the outer tube by welding with a welding current of 190 mA at a welding speed of 185 mm / s, evacuate to a vacuum degree of 0.3 Pa, and perform heat treatment at 950 °C and 1 MPa to obtain the stainless steel composite tube.

[0022] Example 3 A high-toughness antibacterial stainless steel composite tube is composed of a composite of an inner tube and an outer tube. The outer tube is composed of the following components by weight percentage: C 0.22%, Si 0.65%, Cu 3.2%, Al 0.4%, Mn 0.25%, V 0.16%, B 0.18%, Mo 0.2%, Ni 0.48%, La 0.15%, Cr 0.55%, P 0.023%, S 0.01%, N 0.008%, and the balance is iron and unavoidable impurities; The inner tube is composed of the following components by weight percentage: Ni 0.55%, Mo 0.2%, W 0.3%, Fe 0.26%, Ag 0.09%, V 0.26%, Y 0.085%, P 0.015%, S 0.01%, and the balance is copper and unavoidable impurities; A preparation method of a high-toughness antibacterial stainless steel composite tube includes the following steps: S1. Weigh and mix the components of the outer tube, melt, refine, continuously cast, pierce, heat in a H2-CO-CH4 mixed atmosphere with a volume ratio of 2:20:1, roll, perform quenching treatment at 910 °C for 2 h, then cool to room temperature, perform tempering treatment at 650 °C for 1 h, and then cool to room temperature to obtain the outer tube; S2. Weigh and mix the components of the inner tube, melt, refine, continuously cast, pierce, roll, perform quenching treatment at 860 °C for 2 h, then cool to room temperature, perform tempering treatment at 600 °C for 1 h, and then cool to room temperature to obtain the inner tube; S3. Insert the inner tube into the outer tube until the bottom, seal one end of the outer tube by welding with a welding current of 250 mA at a welding speed of 195 mm / s, evacuate to a vacuum degree of 0.35 Pa, and perform heat treatment at 980 °C and 1.2 MPa to obtain the stainless steel composite tube.

[0023] Example 4 The difference between this embodiment and Embodiment 2 is only that, in this embodiment, the weight percentage of Al added to the outer tube is 0.34%, the weight percentage of B added is 0.096%, and the weight percentage of La added is 0.064%.

[0024] Embodiment 5 The difference between this embodiment and Embodiment 2 is only that, in this embodiment, the weight percentage of Al added to the outer tube is 0.25%, the weight percentage of B added is 0.15%, and the weight percentage of La added is 0.1%.

[0025] Embodiment 6 The difference between this embodiment and Embodiment 2 is only that, in this embodiment, the weight percentage of Al added to the outer tube is 0.3%, the weight percentage of B added is 0.12%, and the weight percentage of La added is 0.08%.

[0026] Embodiment 7 The difference between this embodiment and Embodiment 6 is only that, in this embodiment, in step S2, the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 4:55:2.

[0027] Embodiment 8 The difference between this embodiment and Embodiment 6 is only that, in this embodiment, in step S2, the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 4:45:2.

[0028] Embodiment 9 The difference between this embodiment and Embodiment 6 is only that, in this embodiment, in step S2, the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 4:47:1.

[0029] Embodiment 10 The difference between this embodiment and Embodiment 6 is only that, in this embodiment, in step S2, the volume ratio of H2, CO, and CH4 in the mixed atmosphere is 2:25:1.

[0030] Comparative Example 1 The difference between this comparative example and Embodiment 1 is only that, in this comparative example, La is not added to the outer tube, the weight percentage of Al added is 0.14%, and the weight percentage of B added is 0.1%.

[0031] Comparative Example 2 The difference between this comparative example and Embodiment 1 is only that, in this comparative example, B is not added to the outer tube, the weight percentage of Al added is 0.14%, and the weight percentage of La added is 0.1%.

[0032] Comparative Example 3 The difference between this comparative example and Example 1 is only that in this comparative example, Al is not added to the outer tube, the weight percentage of B added is 0.12%, and the weight percentage of La added is 0.12%.

[0033] Comparative Example 4 The difference between this comparative example and Example 1 is only that in this comparative example, B and La are not added to the outer tube, and the weight percentage of Al added is 0.24%.

[0034] Comparative Example 5 The difference between this comparative example and Example 1 is only that in this comparative example, neither Al, B nor La is added to the outer tube.

[0035] Experimental Example 1 Impact Toughness Test The outer tubes of the stainless steel composite pipes prepared in Examples 1-6 and Comparative Examples 1-5 were tested for impact energy absorption according to the method in GB / T 229-2020 "Metallic materials - Charpy pendulum impact test method". Among them, specimens with dimensions of 55 mm × 10 mm × 10 mm were intercepted from the stainless steel composite pipes, V-notch specimens, the specimen depth was 2 mm, and the test temperatures were 23 °C and -25 °C. The test results are shown in Table 1 below: Table 1 Impact toughness test results of Examples 1-6 and Comparative Examples 1-5

[0036] As can be seen from Table 1, compared with Comparative Examples 1-5, the outer tubes of the stainless steel composite pipes in Examples 1-6 have an impact energy absorption > 255 J at 23 °C and > 231 J at -25 °C, indicating that by introducing Al, B, and La into the outer tube of the stainless steel composite pipe and optimizing the content ratio of Al, B, and La, the impact toughness of the outer tube of the stainless steel composite pipe is significantly improved, thereby improving the overall impact toughness of the stainless steel composite pipe. Compared with Examples 2 and 4, the outer tubes of the stainless steel composite pipes in Examples 5-6 have increased impact energy absorption at 23 °C and -25 °C, indicating that when the weight percentages of Al, B, and La satisfy the relationship of 1 ≤ Al / (B + La) ≤ 1.5, the impact toughness of the stainless steel composite pipe can be further improved.

[0037] Experimental Example 2 Wear Resistance The stainless steel composite pipes prepared in Examples 6-10 were subjected to a scouring test using sediment containing 35 wt% silica. The wear condition of the specimens was observed with the naked eye, and the mass loss rate was calculated. Among them, the specimen length was 700 mm, the scouring pressure was 1.0 MPa, the scouring time was 24 h, and the mass loss rate (%) = (mass of the specimen before the scouring test - mass of the specimen after the scouring test) / mass of the specimen before the scouring test × 100%. The results are shown in Table 2 below: Table 2 Wear resistance test results of Examples 6 to 10

[0038] As can be seen from Table 2, compared with Examples 6 to 7, the mass loss rate of Examples 8 to 10 decreases, indicating that when the outer tube blank is heated in a mixed atmosphere of H2-CO-CH4, by adjusting the volume of each gas component in the mixed atmosphere, when the volume ratio of H2, CO and CH4 in the mixed atmosphere is 4:45-50:2, the overall wear resistance of the stainless steel composite pipe can be improved.

[0039] Experimental Example 3 Antibacterial performance test The antibacterial performance of the outer surface of the stainless steel composite pipe prepared in Example 1 against Escherichia coli and Staphylococcus aureus was detected according to the method in GB / T 42675-2023 "Welded Steel Pipes and Fittings for Antibacterial Stainless Steel". Among them, the wet detection method was selected, and the selected concentrations of the bacterial suspension were 2.0×10 5 CFU / mL, and the test results are shown in Table 3 below: Table 3 Antibacterial performance test of Example 1

[0040] As can be seen from Table 3, the antibacterial rates of the stainless steel composite pipe prepared in Example 1 against Escherichia coli and Staphylococcus aureus are both >96.0%, indicating that the stainless steel composite pipe prepared by this solution has good antibacterial performance and meets the standard of antibacterial performance.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-toughness antibacterial stainless steel composite pipe, which is composed of an inner layer pipe and an outer layer pipe, and is characterized in that, The outer layer tube is composed of components with the following weight percentages: C 0.16% - 0.22%, Si 0.45% - 0.65%, Cu 1.5% - 3.2%, Al 0.14% - 0.4%, Mn 0.15% - 0.25%, V 0.08% - 0.16%, B 0.05% - 0.18%, Mo 0.12% - 0.2%, Ni 0.34% - 0.48%, La 0.05% - 0.15%, Cr 0.15% - 0.55%, P ≤ 0.023%, S ≤ 0.01%, N ≤ 0.008%, and the balance is iron and inevitable impurities.

2. The high-toughness antibacterial stainless steel composite pipe according to claim 1, characterized in that, The weight percentages of Al, B, and La satisfy the following relationship: 1 ≤ Al / (B + La) ≤ 1.

5.

3. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 1, characterized in that, The inner layer tube is composed of components with the following weight percentages: Ni 0.45% - 0.55%, Mo 0.1% - 0.2%, W 0.25% - 0.3%, Fe 0.16% - 0.26%, Ag 0.03% - 0.09%, V 0.1% - 0.26%, Y 0.015% - 0.085%, P ≤ 0.015%, S ≤ 0.01%, and the balance is copper and inevitable impurities.

4. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to any one of claims 1 to 3, characterized in that, It includes the following steps: S1. Weigh and mix the components of the outer layer tube according to the specified weight, melt, refine, continuously cast, pierce, heat, roll, and perform heat treatment to obtain the outer layer tube. S2. Weigh and mix the components of the inner layer tube according to the specified weight, melt, refine, continuously cast, pierce, roll, and perform heat treatment to obtain the inner layer tube. S3. Insert the inner layer tube into the outer layer tube until the bottom, seal one end of the outer layer tube, evacuate to a vacuum, and perform heat treatment to obtain a stainless steel composite tube.

5. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 4, characterized in that, In step S1, during the heating process, the heating atmosphere is a mixed atmosphere of H2 - CO - CH4.

6. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 5, characterized in that, In the mixed atmosphere, the volume ratio of H2, CO, and CH4 is 4:45 - 50:

2.

7. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 4, characterized in that, In step S1, during the heat treatment, after quenching at 700 - 910 °C, the time is 2 - 3 h, and then it is cooled to room temperature; after tempering at 400 - 650 °C, the time is 1 - 2 h, and then it is cooled to room temperature. In step S2, during the heat treatment, after quenching at 750 - 860 °C, the time is 2 - 3 h, and then it is cooled to room temperature; after tempering at 450 - 600 °C, the time is 1 - 2 h, and then it is cooled to room temperature.

8. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 4, characterized in that, In step S3, during the evacuation, evacuate to a vacuum degree of 0.1 - 0.5 Pa.

9. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 4, characterized in that, During the sealing, the welding current is 150 - 250 mA, and the welding speed is 175 - 195 mm / s.

10. The preparation method of a high-toughness antibacterial stainless steel composite pipe according to claim 4, characterized in that, During the heat treatment, the temperature is 920 - 980 °C, and the pressure is 0.8 - 1.2 MPa.

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