Thin-walled stainless steel tube for fluid delivery and method of manufacture and use thereof

Abstract

The present application belongs to the technical field of stainless steel pipe manufacturing, and particularly relates to a thin-wall stainless steel pipe for fluid delivery and a preparation method and application thereof. The thin-wall stainless steel pipe for fluid delivery comprises the following components in percentage by mass: C: 0.01-0.03%, Si: 0.5-0.7%, Mn: 3-6%, P: ≤0.04%, S: ≤0.01%, Cr: 20-25%, Ni: 8-12%, N: 0.2-0.5%, Mo: 2-3%, Nb: 0.05-0.1%, Ce: 0.05-0.15%, Zr: 0.05-0.2%, Te: 0.01-0.02%, and the balance of Fe and inevitable impurities. The present application obtains the thin-wall stainless steel pipe for fluid delivery which is excellent in resistance to chlorine ions and oxalic acid by optimizing the raw material formula, and has a wide application prospect in resident gas delivery.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel pipe manufacturing technology, specifically relating to a thin-walled stainless steel pipe for fluid transportation, its preparation method, and its application. Background Technology

[0002] Thin-walled stainless steel pipes possess corrosion resistance, high-temperature resistance, and environmental friendliness, making them widely used as fluid transport tools in petroleum, chemical, energy, metallurgical heat transmission, and water supply and drainage fields. In recent years, thin-walled stainless steel pipes have gradually replaced hot-dip galvanized steel pipes, aluminum-plastic composite pipes, and other gas pipeline materials for residential gas transportation.

[0003] When thin-walled stainless steel pipes are used as residential gas pipelines, their main applications are low-pressure external risers and kitchen pipes. Installation typically occurs after the main building construction is completed but before interior decoration begins. During interior decoration or exterior wall plastering, decorating companies usually do not take protective measures for the installed thin-walled stainless steel gas pipes, resulting in cement mortar and decoration materials directly covering the pipe surface, sometimes even completely encasing it. After decoration, oxalic acid is often used for cleaning. The chloride ions in cement mortar and decoration materials, as well as oxalic acid, especially oxalic acid exposed to air, corrode the stainless steel pipes. This leads to surface and pitting corrosion during use, ranging from minor rust spots and shallow pits to severe rust leaks. Furthermore, strong acidic cleaning agents are often used in kitchens to remove stubborn dirt, further contributing to the corrosion of the thin-walled stainless steel pipes.

[0004] However, current technologies for stainless steel pipes used in fluid transportation primarily focus on resistance to chloride ion corrosion. For example, Chinese Patent Publication No. CN 120608249 A discloses a cold-drawn seamless stainless steel pipe for fluid transportation and its preparation method. The pipe comprises the following components by mass percentage: C: ≤0.02%, Si: 0.4~0.6%, Mn: 7.5~8.0%, Cr: 16.5~17.5%, Ni: 3.5~4.5%, Al: 0.01~0.05%, N: 0.25~0.30%, S: 0.015~0.002%, Ca: 0.003~0.004%, with Fe as the balance, and the mass ratio of Ca to S is controlled at 1~2. Optionally, it also includes microalloying elements such as Nb, Ti, and Mo, and specifies key ratio parameters such as Mn / N, Mn / Ni, and Ti / N. The steel pipe achieves spheroidization and plasticity of inclusion morphology through the Ca / S inclusion modification mechanism in conjunction with the austenite stabilizing component ratio design, significantly reducing the sensitivity to cold drawing cracks; at the same time, it constructs a synergistic strengthening system of strength, toughness and corrosion resistance to improve the reliability of the material in service. Its claimed corrosion resistance was tested using a 3.5% NaCl solution.

[0005] There are currently few reports on research specifically addressing the technical problems associated with thin-walled stainless steel pipes used for residential gas transmission. Summary of the Invention

[0006] 1. The problem to be solved Existing technologies do not specifically address the issue of requiring thin-walled stainless steel pipes for residential gas transmission to be resistant to both chloride ions and oxalic acid. This invention provides a thin-walled stainless steel pipe for fluid transportation, achieving excellent resistance to both chloride ions and oxalic acid through optimized raw material formulation.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a thin-walled stainless steel pipe for fluid transport, comprising the following components by mass percentage: C: ≤0.03%, Si: ≤0.7%, Mn: 3-6%, P: ≤0.04%, S: ≤0.01%, Cr: 20-25%, Ni: 8-12%, N: 0.2-0.5%, Mo: 2-3%, Nb: 0.05-0.1%, Ce: 0.05-0.15%, Zr: 0.05-0.2%, Te: 0.01-0.02%, and the balance being Fe and unavoidable impurities.

[0008] Furthermore, the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.01-0.03%, Si: 0.5-0.7%, Mn: 3-6%, P: ≤0.04%, S: ≤0.01%, Cr: 20-25%, Ni: 8-12%, N: 0.2-0.5%, Mo: 2-3%, Nb: 0.05-0.1%, Ce: 0.05-0.15%, Zr: 0.05-0.2%, Te: 0.01-0.02%, and the balance being Fe and unavoidable impurities.

[0009] Furthermore, the mass ratio of Mn, Ni and N is 10-20:30-50:1.

[0010] Furthermore, Ce+Nb≤0.2%.

[0011] Furthermore, the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, Te: 0.015%, and the balance being Fe and unavoidable impurities.

[0012] 316L austenitic stainless steel contains 2-3% molybdenum, which can improve resistance to chloride pitting corrosion, but its protective effect against organic acids such as oxalic acid is not significant. This invention is based on 316L austenitic stainless steel material. By optimizing its composition and content, especially by adding specific amounts of N, Nb, Ce, Zr, and Te components and optimizing the content of Cr and Ni, the 316L austenitic stainless steel eliminates intergranular segregation and harmful phase precipitation, and improves the stability of the passivation film. Thus, thin-walled stainless steel pipes have excellent resistance to chloride corrosion as well as excellent resistance to oxalic acid corrosion.

[0013] The working principle of the constituent elements of the thin-walled stainless steel pipe for fluid transportation described in this invention is as follows: C, P, S: The presence of C will reduce the electrode potential of iron and reduce corrosion resistance, but it can improve the strength of the material. Therefore, the content of C is controlled at 0.01-0.03%. P and S are impurity elements, and the lower the content, the better.

[0014] Si: Si can improve the strength of thin-walled stainless steel pipes, but adding too much can easily produce silica inclusions, which not only leads to a decrease in strength, but also to a decrease in corrosion resistance. Therefore, the present invention controls its content to be 0.5-0.7%.

[0015] Mn, N, Ni: Mn, N, and Ni are austenitic stainless steel forming elements that can improve the corrosion resistance of thin-walled stainless steel pipes. However, Ni is expensive. This invention reduces the Ni content by adding N and increasing the Mn content. However, in this invention, the mass ratio of Mn, Ni, and N must be controlled at 10-20:30-50:1, otherwise the corrosion resistance of the resulting thin-walled stainless steel pipe will decrease.

[0016] Cr: Cr is a key factor related to the corrosion of thin-walled stainless steel pipes. Its role is multifaceted. This invention increases the Cr content to form a highly corrosion-resistant passivation film to prevent the passivation film from breaking down, and to increase the electrode potential of Fe.

[0017] Mo: Improves the repassivation capability of the passivation film on thin-walled stainless steel tubes and reduces the dissolution rate in pitting pores.

[0018] Nb: Prevents Cr from combining with C in thin-walled stainless steel pipes to form carbides, which would reduce the chromium content.

[0019] Ce: It can form inclusions of cerium oxide and silica, avoiding the influence of silica inclusions. However, due to Ce's strong affinity for O and S, the Ce oxide and oxysulfide formed aggregate to form rare earth inclusion clusters, which leads to a decrease in corrosion resistance. Therefore, its content is controlled to be no higher than 0.15%.

[0020] Zr: It can form a grain refinement layer, preventing further corrosion.

[0021] Te: It can form MnTe inclusions, avoid the influence of MnS inclusions, and further improve the stability of the passivation film.

[0022] Furthermore, the wall thickness of the thin-walled stainless steel pipe for fluid transport is 1-1.6 mm, and the outer diameter is 18-108 mm.

[0023] Secondly, the present invention provides a method for preparing a thin-walled stainless steel pipe for fluid transportation, comprising the following steps: (1) Smelt according to the formula to obtain molten steel, and use the molten steel to cast and hot forge into tube blanks; (2) The tube blank is subjected to extrusion, first heat treatment, first pickling, first cold rolling, first degreasing, second heat treatment, second pickling, second cold rolling, and second degreasing in sequence to obtain thin-walled stainless steel tube for fluid transportation.

[0024] Furthermore, the temperature of the first heat treatment and the second heat treatment are 1100-1200℃, and the time is 20-30min.

[0025] The pickling, cold rolling, and degreasing conditions in the preparation method of this invention can be the conventional processing conditions in the field.

[0026] Thirdly, the present invention provides an application of thin-walled stainless steel pipe for fluid transportation in residential gas transportation.

[0027] 3. Beneficial effects: This invention is based on 316L austenitic stainless steel material. By optimizing its composition and content, especially by adding specific amounts of N, Nb, Ce, Zr, and Te components and optimizing the content of Cr and Ni, the 316L austenitic stainless steel eliminates intergranular segregation and harmful phase precipitation, and improves the stability of the passivation film. As a result, thin-walled stainless steel pipes have excellent resistance to chloride corrosion as well as excellent resistance to oxalic acid corrosion. Attached Figure Description

[0028] Figure 1The images shown are actual photos of the products after the internal laboratory corrosion resistance tests of Examples 1-3 and Comparative Examples 1-7 were completed; where A is Example 1, B is Example 2, C is Example 3, D is Comparative Example 1, E is Comparative Example 2, F is Comparative Example 3, G is Comparative Example 4, H is Comparative Example 5, I is Comparative Example 6, and J is Comparative Example 7. Detailed Implementation

[0029] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0030] Unless otherwise specified, the raw materials, reagents or apparatus used in the following examples and comparative examples are available from conventional commercial sources or can be obtained by existing known methods.

[0031] Example 1 A thin-walled stainless steel pipe for fluid transport, comprising the following components by weight percentage: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, Te: 0.015%, and the balance being Fe and unavoidable impurities.

[0032] The method for preparing the thin-walled stainless steel pipe for fluid transportation includes the following steps: (1) Smelt according to the formula to obtain molten steel, and use the molten steel to cast and hot forge into tube blanks; (2) The tube blank is subjected to extrusion, first heat treatment, first pickling, first cold rolling, first degreasing, second heat treatment, second pickling, second cold rolling, and second degreasing in sequence to obtain thin-walled stainless steel tube for fluid transportation.

[0033] The first and second heat treatments were performed at a temperature of 1150°C for 20 minutes.

[0034] The pickling, cold rolling, and degreasing conditions in the preparation method can be the conventional processing conditions in this field.

[0035] The obtained thin-walled stainless steel pipe for fluid transport has a wall thickness of 1.55 mm and an outer diameter of 42.01 mm.

[0036] Example 2 A thin-walled stainless steel pipe for fluid transport, comprising the following components by weight percentage: C: 0.024%, Si: 0.57%, Mn: 6%, P: 0.033%, S: 0.005%, Cr: 23%, Ni: 10%, N: 0.5%, Mo: 2.01%, Nb: 0.06%, Ce: 0.10%, Zr: 0.12%, Te: 0.01%, and the balance being Fe and unavoidable impurities.

[0037] The method for preparing the thin-walled stainless steel pipe for fluid transportation includes the following steps: (1) Smelt according to the formula to obtain molten steel, and use the molten steel to cast and hot forge into tube blanks; (2) The tube blank is subjected to extrusion, first heat treatment, first pickling, first cold rolling, first degreasing, second heat treatment, second pickling, second cold rolling, and second degreasing in sequence to obtain thin-walled stainless steel tube for fluid transportation.

[0038] The first and second heat treatments were performed at a temperature of 1150°C for 20 minutes.

[0039] The pickling, cold rolling, and degreasing conditions in the preparation method can be the conventional processing conditions in this field.

[0040] The resulting thin-walled stainless steel pipe for fluid transport has a wall thickness of 1.43 mm and an outer diameter of 34.93 mm.

[0041] Example 3 A thin-walled stainless steel pipe for fluid transport, comprising the following components by weight percentage: C: 0.016%, Si: 0.48%, Mn: 4%, P: 0.037%, S: 0.005%, Cr: 24%, Ni: 10%, N: 0.2%, Mo: 2.06%, Nb: 0.08%, Ce: 0.13%, Zr: 0.08%, Te: 0.02%, and the balance being Fe and unavoidable impurities.

[0042] The method for preparing the thin-walled stainless steel pipe for fluid transportation includes the following steps: (1) Smelt according to the formula to obtain molten steel, and use the molten steel to cast and hot forge into tube blanks; (2) The tube blank is subjected to extrusion, first heat treatment, first pickling, first cold rolling, first degreasing, second heat treatment, second pickling, second cold rolling, and second degreasing in sequence to obtain thin-walled stainless steel tube for fluid transportation.

[0043] The first and second heat treatments were performed at a temperature of 1150°C for 20 minutes.

[0044] The pickling, cold rolling, and degreasing conditions in the preparation method can be the conventional processing conditions in this field.

[0045] The resulting thin-walled stainless steel pipe for fluid transport has a wall thickness of 1.4 mm and an outer diameter of 54 mm.

[0046] Comparative Example 1 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 11.2%, N: 0.6%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, Te: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0047] Comparative Example 2 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 2%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 14.5%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, Te: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0048] Comparative Example 3 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, La: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0049] Comparative Example 4 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0%, Ce: 0.12%, Zr: 0.108%, Te: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0050] Comparative Example 5 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Ta: 0.1%, Te: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0051] Comparative Example 6 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.2%, Ce: 0.12%, Zr: 0.1%, Te: 0.015% and the balance Fe and unavoidable impurities; all others are the same.

[0052] Comparative Example 7 The only difference from Example 1 is that the thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.02%, Zr: 0.3%, Te: 0.008% and the balance Fe and unavoidable impurities; all others are the same.

[0053] Performance testing Performance Test 1: Internal Laboratory Corrosion Resistance Test (1) The pitting potential of the thin-walled stainless steel pipes for fluid transport prepared in Examples 1-3 and Comparative Examples 1-7 in a 3.5% NaCl aqueous solution is shown in Table 1.

[0054] (2) Half of the thin-walled stainless steel pipes for fluid transport prepared in Examples 1-3 and Comparative Examples 1-7 were immersed in a 10% oxalic acid solution, and the other half (the upper part) was exposed to air. They were placed indoors for 30 days, and the corrosion on the surface of the upper part of the stainless steel was observed. The results are shown in Table 1. The actual pictures of the finished products of Examples 1-3 and Comparative Examples 1-7 are shown in Table 1. Figure 1 As shown.

[0055] Table 1 As can be seen from Table 1, the thin-walled stainless steel pipes for fluid transportation prepared in Examples 1-3 have a high pitting potential, and no corrosion was observed in the upper part after being placed in 10% oxalic acid solution for 30 days. In Comparative Examples 1 and 2, the mass ratios of Mn, Ni, and N were not within the range of 10-20:30-50:1. The pitting potential of the prepared thin-walled stainless steel pipes for fluid transport decreased significantly, and corrosion appeared in the upper part after 30 days in a 10% oxalic acid solution. Figure 1 It can be seen that the corrosion is quite severe.

[0056] In Comparative Examples 3-7, changes in the Nb, Ce, Zr, and Te components and their contents significantly reduced the pitting potential of the prepared thin-walled stainless steel pipes for fluid transport. Furthermore, corrosion appeared in the upper part of the pipes after 30 days in a 10% oxalic acid solution. Figure 1 It can be seen that the corrosion of comparative examples 3, 4 and 7 was light, while that of comparative examples 5 and 6 was heavy.

[0057] Table 1 shows that the thin-walled stainless steel pipe for fluid transportation provided by the present invention has excellent corrosion resistance and has broad application prospects in residential gas transportation.

[0058] Performance Test 2: External Laboratory Testing (1) The thin-walled stainless steel pipe for fluid transportation prepared in Example 1 was sent to an external testing facility for dimensional and appearance quality, tensile test, flattening test, flaring test, hydraulic test, air tightness test, intergranular corrosion test, and salt spray test. The results are shown in Table 2.

[0059] Table 2 As can be seen from Table 2, the thin-walled stainless steel for fluid transport provided in Embodiment 1 of the present invention meets the requirements.

[0060] (2) The thin-walled stainless steel pipe for fluid transportation prepared in Example 2 was sent to an external testing facility for dimensional and appearance quality, tensile test, flattening test, flaring test, hydraulic test, air tightness test, intergranular corrosion test, and salt spray test. The results are shown in Table 3.

[0061] Table 3 As can be seen from Table 3, the thin-walled stainless steel for fluid transport provided in Embodiment 2 of the present invention meets the requirements.

[0062] (3) The thin-walled stainless steel pipe for fluid transportation prepared in Example 3 was sent to an external testing facility for dimensional and appearance quality testing, tensile test, flattening test, flaring test, hydraulic test, airtightness test, intergranular corrosion test, and salt spray test. The results are shown in Table 4.

[0063] Table 4 As can be seen from Table 4, the thin-walled stainless steel for fluid transport provided in Embodiment 3 of the present invention meets the requirements.

[0064] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A thin-walled stainless steel pipe for fluid transport, characterized in that, By weight percentage, it includes the following components: C: ≤0.03%, Si: ≤0.7%, Mn: 3-6%, P: ≤0.04%, S: ≤0.01%, Cr: 20-25%, Ni: 8-12%, N: 0.2-0.5%, Mo: 2-3%, Nb: 0.05-0.1%, Ce: 0.05-0.15%, Zr: 0.05-0.2%, Te: 0.01-0.02%, and the balance being Fe and unavoidable impurities; The mass ratio of Mn, Ni and N is 10-20:30-50:

1.

2. The thin-walled stainless steel pipe for fluid transport according to claim 1, characterized in that, The thin-walled stainless steel pipe for fluid transportation, by mass percentage, comprises: C: 0.01-0.03%, Si: 0.5-0.7%, Mn: 3-6%, P: ≤0.04%, S: ≤0.01%, Cr: 20-25%, Ni: 8-12%, N: 0.2-0.5%, Mo: 2-3%, Nb: 0.05-0.1%, Ce: 0.05-0.15%, Zr: 0.05-0.2%, Te: 0.01-0.02%, with the balance being Fe and unavoidable impurities.

3. The thin-walled stainless steel pipe for fluid transportation according to claim 2, characterized in that, The mass ratio of Mn, Ni and N is 15:40:

1.

4. The thin-walled stainless steel pipe for fluid transport according to claim 3, characterized in that, The Ce+Nb≤0.2%.

5. The thin-walled stainless steel pipe for fluid transport according to claim 4, characterized in that, The thin-walled stainless steel pipe for fluid transport comprises, by mass percentage, the following components: C: 0.019%, Si: 0.53%, Mn: 4.5%, P: 0.036%, S: 0.005%, Cr: 23%, Ni: 12%, N: 0.3%, Mo: 2.07%, Nb: 0.08%, Ce: 0.12%, Zr: 0.1%, Te: 0.015%, and the balance being Fe and unavoidable impurities.

6. The thin-walled stainless steel pipe for fluid transport according to claim 1, characterized in that, The wall thickness of the thin-walled stainless steel pipe for fluid transportation is 1-1.6 mm, and the outer diameter is 18-108 mm.

7. A method for preparing a thin-walled stainless steel pipe for fluid transport according to any one of claims 1-6, comprising the following steps: (1) Smelt according to the formula to obtain molten steel, and use the molten steel to cast and hot forge into tube blanks; (2) The tube blank is subjected to extrusion, first heat treatment, first pickling, first cold rolling, first degreasing, second heat treatment, second pickling, second cold rolling, and second degreasing in sequence to obtain thin-walled stainless steel tube for fluid transportation.

8. The method for preparing a thin-walled stainless steel pipe for fluid transportation according to claim 7, characterized in that, The first and second heat treatments are performed at temperatures of 1100-1200℃ for 20-30 minutes.

9. The application of the thin-walled stainless steel pipe for fluid transportation according to any one of claims 1-6 in residential gas transportation.

Images