Low-alloy high-strength hydrogen embrittlement-resistant pipe and preparation method thereof

Abstract

The invention relates to the technical field of material metallurgy, and particularly discloses a low-alloy high-strength hydrogen embrittlement-resistant pipe and a preparation method thereof. On the basis of C-Mn steel, RE, Mo, Nb and Ti alloy elements are added, the carbon equivalent and RE / S are controlled to be larger than or equal to 1, a special cooling mode and a heat treatment process are adopted in a matched mode, and the process conditions of pipe rolling are controlled, so that on the premise that the alloy cost is effectively reduced, the strength, the toughness and the hydrogen brittleness resistance of the pipe are greatly improved, and meanwhile the service life of the pipe is prolonged. And good machining and welding performance is achieved. The grain size of the steel can reach 10-12 grades, the tensile strength is larger than or equal to 570 MPa, the yield strength can reach 485-635 MPa, no crack exists in a 90% stress SSC test, the hydrogen embrittlement sensitivity index is smaller than or equal to 4%, and the steel has good machining and welding performance, can meet the use requirement for pipes in a harsh hydrogen-containing environment and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of material metallurgy, and in particular to a low-alloy high-strength hydrogen embrittlement-resistant pipe and a preparation method thereof. Background Art

[0002] As a zero-carbon energy carrier, hydrogen is considered one of the core pathways to achieving energy transition. According to the International Energy Agency (IEA), by 2050, hydrogen will account for 12% to 15% of global energy consumption, with green hydrogen (hydrogen produced from renewable energy) accounting for over 70%. With the scaled-up development of the hydrogen energy industry chain, pipeline transportation has become the preferred option for long-distance, large-scale hydrogen transportation due to its economic and continuous nature. However, compared to traditional natural gas pipelines, hydrogen transportation faces several unique challenges: hydrogen molecules easily adsorb on the surface of steel and penetrate into the material, accumulating at structural defects or stress concentrations, leading to hydrogen embrittlement, delayed hydrogen-induced cracking, or hydrogen blistering in pipeline steel. The presence of impurities such as water vapor and H2S in hydrogen can also trigger stress corrosion cracking and hydrogen-induced cracking. Furthermore, to improve hydrogen transmission efficiency, pipelines must withstand high pressures of 30 to 50 MPa, placing higher demands on material strength and fatigue resistance.

[0003] At present, hydrogen pipelines prefer steel grades of X52 and below. With the increasing demand for hydrogen transportation, the market demand for higher steel grades such as X65 for hydrogen pipelines continues to expand. However, the reliability and stability of commonly used high-strength pipes are greatly reduced in hydrogen-containing environments, and they are prone to crack propagation and even breakage, which brings huge safety hazards and economic losses to production. Although some high-strength steels have improved the strength and toughness of the materials to a certain extent by adding alloying elements and improving heat treatment processes, they still have deficiencies in hydrogen embrittlement resistance and are difficult to meet the needs of modern industry for high-safety and long-life pipes. Therefore, the development of a low-alloy pipe with both high strength and excellent hydrogen embrittlement resistance is of great significance to promoting the development of the hydrogen energy industry. Summary of the Invention

[0004] In view of the fact that the reliability and stability of existing high-strength pipes are greatly reduced in hydrogen-containing environments, and they are prone to crack expansion and even breakage, the present invention provides a low-alloy high-strength hydrogen embrittlement-resistant pipe and a preparation method thereof.

[0005] To solve the above technical problems, the technical solutions provided by the embodiments of the present invention are:

[0006] A low-alloy high-strength hydrogen embrittlement-resistant pipe, comprising the following components by weight: 0.08%≤C≤0.12%, 0.15%≤Si≤0.35%, 0.3%≤Mn≤0.5%, 0.8%≤Cr≤1.0%, 0.10%≤Mo≤0.20%, 0.02%≤Nb≤0.05%, 0.01%≤Ti≤0.02%, 0.005%≤RE≤0.01%, N≤0.006%, P≤0.01%, S≤0.001%, and the balance being Fe and unavoidable impurities; wherein RE / S≥1, RE is La and / or Ce; CE pcm ≤0.25%.

[0007] Compared with the prior art, the design ideas of the chemical composition of the low-alloy high-strength hydrogen embrittlement resistant pipe provided by the present invention are as follows:

[0008] (1) Controlling the carbon content to 0.08% to 0.12% can provide basic strength for the pipe through solid solution strengthening and the formation of fine carbides, while avoiding the decrease in toughness and deterioration of welding performance caused by excessive carbon content. While ensuring that the pipe has sufficient load-bearing capacity, it is also less likely to suffer brittle fracture under complex working conditions.

[0009] (2) Adding Cr element to C-Mn steel can form a dense Cr2O3 oxide film on the surface of the material, slowing down hydrogen penetration;

[0010] (3) Adding Mo element, Mo easily forms small and stable carbides with C. These precipitated phases can act as irreversible hydrogen traps to capture and fix hydrogen atoms, reducing the diffusion and enrichment of free hydrogen. In addition, Mo atomic radius is large, which can distort the lattice and increase the resistance to hydrogen diffusion.

[0011] (4) Adding rare earth elements La and / or Ce: First, rare earth elements have a strong affinity with oxygen and sulfur, and can form small high-melting-point RE2O3 and RES compounds, forming high-density irreversible hydrogen traps, which can significantly reduce the diffusion coefficient of hydrogen and reduce the concentration of free hydrogen; second, their addition can also transform long strip-shaped MnS inclusions into spherical rare earth sulfur oxides RE2O2S, reducing stress concentration sources; third, rare earth elements are concentrated at grain boundaries, hindering grain boundary migration, and inhibiting the growth of austenite grains during rolling; fourth, RE can promote the selective oxidation of elements such as Cr, forming a dense and continuous Cr2O3 / RE composite oxide film, which inhibits hydrogen penetration;

[0012] (5) Adding Nb element, RE and Nb synergistically combine with carbon and nitrogen to form nanoscale RE-C / N and RE-NbC / N precipitation phases, forming irreversible hydrogen traps. Its binding energy with hydrogen is high, which can uniformly capture hydrogen atoms and avoid local enrichment of hydrogen atoms;

[0013] (6) Adding Ti element, Ti can react with RE to form a special second phase of finely dispersed oxysulfur nitride, which can refine the grains during the pipeline welding process;

[0014] (7) Control RE / S≥1, rare earth elements can react quickly with sulfur in steel to form high-melting-point rare earth sulfides. During the solidification of molten steel, they will be evenly distributed in the steel in the form of small, dispersed particles, avoiding the formation of low-melting-point eutectics due to sulfur and aggregation at the grain boundaries, thereby effectively reducing the risk of cracking caused by grain boundary weakening during hot working and improving the overall strength of the steel after hot working; at the same time, rare earth sulfides replace the iron sulfides that are harmful to the performance of steel, purify the steel structure, and lay a good foundation for subsequent strengthening treatment; and when RE / S≥1, rare earth atoms will act as heterogeneous nucleation cores during the solidification of molten steel, increase the number of crystal nuclei, and inhibit the growth of grains, thereby refining the grain size; in addition, when RE / S≥1, the segregation of rare earth elements at the grain boundaries is more sufficient, which can inhibit the aggregation of hydrogen atoms at the grain boundaries, further reducing the risk of hydrogen embrittlement and greatly improving the hydrogen embrittlement resistance of the pipe in a hydrogen-containing environment;

[0015] (8) Controlling CEpcm≤0.25% effectively reduces the hardening tendency of steel and the sensitivity of welding cold cracks, reduces processing defects, and further improves the strength, toughness and hydrogen embrittlement resistance of the pipe.

[0016] The aforementioned components, combined in specific proportions, effectively refine the steel's grain size, significantly improving its strength, toughness, and hydrogen embrittlement resistance. Furthermore, the steel's low alloying element content results in low production costs. The steel's grain size can reach levels 10 to 12, with a tensile strength ≥570 MPa and a yield strength of 485 to 635 MPa. Using an input energy of 2.5 kJ / mm2 for welding, the weld's heat-affected zone (HAZ) can achieve an impact energy of 215 to 235 J at -40°C. The 90% stress SSC test shows no cracks, and the hydrogen embrittlement sensitivity index is ≤4%. The steel exhibits excellent processing and welding properties, meeting the requirements for pipes used in harsh hydrogen-containing environments in the petroleum, chemical, and natural gas industries. It effectively extends the pipe's service life, reduces equipment maintenance costs, and improves the safety and reliability of industrial production. The steel possesses significant technical advantages and broad application prospects.

[0017] Furthermore, the metallographic structure of the low-alloy high-strength hydrogen embrittlement resistant pipe is ferrite+tempered bainite, and the grain size is 10 to 12 levels.

[0018] The present invention also provides a method for preparing the above-mentioned low-alloy high-strength hydrogen embrittlement-resistant pipe, comprising the following steps:

[0019] A continuous casting round billet having the same chemical composition as the low-alloy high-strength hydrogen embrittlement resistant pipe is heated in an annular furnace, punched to form a rough pipe, the rough pipe is rolled to form a rough pipe, the rough pipe is subjected to slight tension reduction and water cooling to form a seamless steel pipe;

[0020] The seamless steel pipe is subjected to tempering heat treatment to obtain a low-alloy high-strength hydrogen embrittlement-resistant pipe.

[0021] The preparation method of the low-alloy high-strength hydrogen embrittlement resistant pipe provided by the present invention has a simple preparation process and is easy to implement in production.

[0022] Furthermore, the continuous casting round billet is made by subjecting steelmaking raw materials to electric arc furnace melting, ladle refining, RH vacuum refining and continuous casting processes.

[0023] Furthermore, after the RH vacuum refining is completed, the Fe-RE alloy wire is inserted into the bottom of the ladle at a speed of 2 m / s to 4 m / s.

[0024] After the RH vacuum refining is completed, the rare earth alloy is inserted into the bottom of the ladle at a speed of 2m / s to 4m / s. This allows the alloy wire to fully contact the molten steel and gradually dissolve during the process of slowly sinking in the molten steel, ensuring that the rare earth elements are evenly diffused into the molten steel, improving the recovery rate of rare earth elements, and ensuring the consistency and stability of the pipe composition.

[0025] Furthermore, after the RH vacuum refining is completed, the temperature of the molten steel is controlled at 1550℃~1600℃, and the Fe-RE alloy wire is fed. At the same time, the argon flow rate at the bottom of the ladle is 0.3Nm 3 / min·t~0.6Nm 3 / min·t.

[0026] The molten steel temperature is controlled between 1550°C and 1600°C to allow the rare earth alloy wire to be fed. Within this temperature range, the molten steel exhibits excellent fluidity, providing favorable conditions for the dissolution of the alloy wire and the diffusion of the rare earth elements, accelerating the fusion of the alloy elements with the molten steel. This also helps the rare earth elements fully react with impurities such as sulfur and oxygen in the molten steel to form stable rare earth compounds, effectively removing impurities and purifying the molten steel. Bottom-blowing argon while feeding the rare earth alloy wire facilitates the rapid and even dispersion of the rare earth elements throughout the molten steel, avoiding localized concentrations that are too high or too low. Furthermore, the bubbles generated by the bottom-blown argon can cause inclusions in the molten steel to float, causing them to gather on the surface, making them easier to remove and further improving the purity of the molten steel.

[0027] Furthermore, the perforation temperature is 1150°C to 1250°C, the rolling temperature is 1000°C to 1100°C, and the micro-tension reducing temperature is 800°C to 900°C.

[0028] Micro-tension reducing at a temperature of 800℃~900℃ in the non-crystallizing zone can induce the precipitation of Nb / Ti carbonitrides and refine the austenite grains.

[0029] Furthermore, the water cooling has a cooling rate of 15°C / s to 30°C / s, and the water cooling is performed to a temperature of 500°C to 600°C.

[0030] After micro-tension reducing, rapid water cooling is used to obtain fine-grained ferrite + bainite structure and refine the grains. Compared with conventional processes, the subsequent quenching process can be omitted, thereby improving production efficiency.

[0031] Furthermore, the tempering heat treatment process includes the following steps: heating the seamless steel pipe to 660° C. to 700° C. and keeping the temperature, and air cooling.

[0032] Furthermore, in the tempering heat treatment process, the seamless steel pipe is kept at 660° C. to 700° C. for 10 minutes to 15 minutes.

[0033] Tempering at 660°C to 700°C is beneficial for fully and effectively eliminating residual stress and improving the stability of the internal structure of the pipe. This allows for more even stress distribution when subjected to complex loads such as internal pressure and external force impact during hydrogen transportation, reduces local stress concentration, and improves the pipe's resistance to deformation and fracture. At the same time, tempering at 660°C to 700°C can effectively reduce microscopic defects within the pipe, refine the grains, and form a large number of small-angle grain boundaries. Small-angle grain boundaries act as reversible hydrogen traps, where hydrogen accumulation is insufficient to reach a concentration conducive to crack nucleation, significantly enhancing the service life and reliability of the pipe in hydrogen transportation environments.

[0034] The beneficial effects of adopting the above technical solution are:

[0035] In the present invention, by adding RE, Mo, Nb, and Ti alloy elements to C-Mn steel, the carbon equivalent and RE / S are controlled to be ≥1, and a special cooling method and heat treatment process are adopted in combination with the control of the process conditions for pipe rolling. Under the premise of effectively reducing the alloy cost, the strength, toughness, and hydrogen embrittlement resistance of the pipe are greatly improved, and at the same time, the pipe has good processing and welding properties. The pipe can be widely used in the field of hydrogen energy transportation and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the metallographic structure diagram of the low-alloy, high-strength, hydrogen embrittlement-resistant pipe prepared in Example 1 of the present invention;

[0037] Figure 2 This is the metallographic structure diagram of the low-alloy, high-strength, hydrogen embrittlement-resistant pipe prepared in Example 2 of the present invention;

[0038] Figure 3 This is the metallographic structure diagram of the low-alloy, high-strength, hydrogen embrittlement-resistant pipe prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] In order to better illustrate the present invention, further examples are given below.

[0041] Example 1

[0042] The embodiment of the present invention provides a low-alloy high-strength hydrogen embrittlement resistant pipe, the weight percentage of which is as follows:

[0043] C 0.08%, Si 0.15%, Mn 0.3%, Cr 0.8%, Mo 0.1%, Nb 0.02%, Ti 0.01%, La 0.002%, Ce 0.003%, N 0.004%, S 0.001%, P 0.008%, and the balance is Fe and inevitable impurities.

[0044] The preparation steps of the above-mentioned low-alloy high-strength hydrogen embrittlement resistant pipe are as follows:

[0045] S1, using 90% direct reduced iron + 10% scrap steel as steelmaking raw materials, the steelmaking raw materials are subjected to 100t electric arc furnace melting, ladle refining, RH vacuum refining, and continuous casting processes to produce continuous casting round billets with a diameter of 450mm, the same chemical composition as the above-mentioned pipe;

[0046] S2, the continuously cast round billet is heated in an annular furnace, punched to form a rough pipe, the rough pipe is rolled by a three-roller continuous rolling mill to obtain a rough pipe, the rough pipe is removed by a three-stand pipe removal machine, slightly tension-reduced, and water-cooled to form a seamless steel pipe;

[0047] S3, heating the seamless steel pipe to 680° C. and keeping the temperature for 12 minutes, and then air-cooling the seamless steel pipe to room temperature to obtain an X70 low-alloy high-strength hydrogen embrittlement-resistant pipe with an outer diameter of 457 mm and a wall thickness of 15.9 mm.

[0048] After RH vacuum refining, the temperature of the molten steel is controlled at 1580℃, and the Fe-RE alloy wire is inserted into the bottom of the ladle at a speed of 3m / s. While feeding the wire, argon is blown from the bottom of the ladle at a flow rate of 0.5Nm 3 / min·t.

[0049] The piercing temperature is 1200°C, the rolling temperature is 1050°C, and the micro-tension reducing temperature is 850°C; the cooling rate of water cooling is 25°C / s, and the water cooling temperature is 550°C.

[0050] The low alloy high strength hydrogen embrittlement resistant pipe prepared by this embodiment mainly has ferrite and tempered bainite as the microstructure, and the grain size is 10 to 12. Figure 1 shown.

[0051] Example 2

[0052] The embodiment of the present invention provides a low-alloy high-strength hydrogen embrittlement resistant pipe, the weight percentage of which is as follows:

[0053] C 0.10%, Si 0.25%, Mn 0.4%, Cr 0.9%, Mo 0.16%, Nb 0.03%, Ti 0.017%, La 0.008%, N 0.005%, S 0.0007%, P 0.007%, and the balance is Fe and inevitable impurities.

[0054] The preparation steps of the above-mentioned low-alloy high-strength hydrogen embrittlement resistant pipe are as follows:

[0055] S1, using 90% direct reduced iron + 10% scrap steel as steelmaking raw materials, the steelmaking raw materials are subjected to 100t electric arc furnace melting, ladle refining, RH vacuum refining, and continuous casting processes to produce continuous casting round billets with a diameter of 450mm, the same chemical composition as the above-mentioned pipe;

[0056] S2, the continuously cast round billet is heated in an annular furnace, punched to form a rough pipe, the rough pipe is rolled by a three-roller continuous rolling mill to obtain a rough pipe, the rough pipe is removed by a three-stand pipe removal machine, slightly tension-reduced, and water-cooled to form a seamless steel pipe;

[0057] S3, heating the seamless steel pipe to 660° C. and keeping the temperature for 15 minutes, and air-cooling the seamless steel pipe to room temperature to obtain an X70 low-alloy high-strength hydrogen embrittlement-resistant pipe with an outer diameter of 457 mm and a wall thickness of 15.9 mm.

[0058] After RH vacuum refining, the temperature of the molten steel is controlled at 1600℃, and the Fe-RE alloy wire is inserted into the bottom of the ladle at a speed of 4m / s. While feeding the wire, argon is blown from the bottom of the ladle at a flow rate of 0.6Nm 3 / min·t.

[0059] The piercing temperature is 1250°C, the rolling temperature is 1100°C, and the micro-tension reducing temperature is 800°C; the cooling rate of water cooling is 15°C / s, and the water cooling temperature is 600°C.

[0060] The low alloy high strength hydrogen embrittlement resistant pipe prepared by this embodiment mainly has ferrite and tempered bainite as the microstructure, and the grain size is 10 to 12. Figure 2 shown.

[0061] Example 3

[0062] The embodiment of the present invention provides a low-alloy high-strength hydrogen embrittlement resistant pipe, the weight percentage of which is as follows:

[0063] C 0.12%, Si 0.35%, Mn 0.5%, Cr 1%, Mo 0.2%, Nb 0.05%, Ti 0.02%, Ce 0.01%, N 0.003%, S 0.0008%, P 0.009%, and the balance is Fe and inevitable impurities.

[0064] The preparation steps of the above-mentioned low-alloy high-strength hydrogen embrittlement resistant pipe are as follows:

[0065] S1, using 90% direct reduced iron + 10% scrap steel as steelmaking raw materials, the steelmaking raw materials are subjected to 100t electric arc furnace melting, ladle refining, RH vacuum refining, and continuous casting processes to produce continuous casting round billets with a diameter of 450mm, the same chemical composition as the above-mentioned pipe;

[0066] S2, the continuously cast round billet is heated in an annular furnace, punched to form a rough pipe, the rough pipe is rolled by a three-roller continuous rolling mill to obtain a rough pipe, the rough pipe is removed by a three-stand pipe removal machine, slightly tension-reduced, and water-cooled to form a seamless steel pipe;

[0067] S3, heating the seamless steel pipe to 700° C. and keeping the temperature for 10 minutes, and air-cooling the seamless steel pipe to room temperature to obtain an X70 low-alloy high-strength hydrogen embrittlement-resistant pipe with an outer diameter of 457 mm and a wall thickness of 15.9 mm.

[0068] After RH vacuum refining, the temperature of the molten steel is controlled at 1550℃, and the Fe-RE alloy wire is inserted into the bottom of the ladle at a speed of 2m / s. While feeding the wire, argon is blown from the bottom of the ladle at a flow rate of 0.3Nm 3 / min·t.

[0069] The piercing temperature is 1150°C, the rolling temperature is 1000°C, and the micro-tension reducing temperature is 900°C; the cooling rate of water cooling is 30°C / s, and the water cooling temperature is 500°C.

[0070] The low alloy high strength hydrogen embrittlement resistant pipe prepared by this embodiment mainly has ferrite and tempered bainite as the microstructure, and the grain size is 10 to 12. Figure 3 shown.

[0071] Performance Testing

[0072] The low alloy high strength hydrogen embrittlement resistant pipes prepared in Examples 1 to 3 were sampled and subjected to tensile tests according to ASTM G129-00 standard with a tensile strength of 2×10 -5 s -1Comparative tensile tests were conducted in 20 MPa hydrogen and nitrogen environments at a strain rate of 2.5 kJ / mm. SSC testing was performed at 90% of the loading stress according to NACE TM0177. The weld heat-affected zone (HAZ) impact toughness at -40°C was tested using an input energy of 2.5 kJ / mm. The results are shown in Table 1.

[0073] Hydrogen embrittlement sensitivity index = 1-elongation in hydrogen environment / elongation in nitrogen environment

[0074] Table 1

[0075]

[0076] In summary, the pipe prepared by the present invention has excellent metallurgical properties, low content of harmful elements, fine and uniform microstructure, excellent resistance to hydrogen embrittlement, reliable mechanical properties, and low production cost. It can be widely used in the field of hydrogen energy transportation and has broad market prospects.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low alloy high strength hydrogen embrittlement resistant pipe, characterized in that: The composition weight percentage is as follows: 0.08%≤C≤0.12%, 0.15%≤Si≤0.35%, 0.3%≤Mn≤0.5%, 0.8%≤Cr≤1.0%, 0.10%≤Mo≤0.20%, 0.02%≤Nb≤0.05%, 0.01%≤Ti≤0.02%, 0.005%≤RE≤0.01%, N≤0.006%, P≤0.01%, S≤0.001%, and the balance is Fe and unavoidable impurities; wherein RE / S≥1, RE is La and / or Ce; CE pcm ≤0.25%.

2. The low alloy high strength hydrogen embrittlement resistant pipe according to claim 1, characterized in that: Its metallographic structure is ferrite + tempered bainite, and the grain size is 10 to 12 levels.

3. The low alloy high strength hydrogen embrittlement resistant pipe according to claim 1, characterized in that: Its tensile strength is ≥570MPa; its yield strength can reach 485~635MPa; its hydrogen embrittlement sensitivity index is ≤4%; and when welding with an input energy of 2.5kJ / mm, the impact energy of the heat-affected zone of the weld at -40℃ can reach 215~235J.

4. A method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to any one of claims 1 to 3, characterized in that: The steps include: A continuous casting round billet having the same chemical composition as the low-alloy high-strength hydrogen embrittlement resistant pipe is heated in an annular furnace, punched to form a rough pipe, the rough pipe is rolled to form a rough pipe, the rough pipe is subjected to slight tension reduction and water cooling to form a seamless steel pipe; The seamless steel pipe is subjected to tempering heat treatment to obtain a low-alloy high-strength hydrogen embrittlement-resistant pipe.

5. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 4, characterized in that: The continuous casting round billet is made by subjecting steelmaking raw materials to electric arc furnace melting, ladle refining, RH vacuum refining and continuous casting processes.

6. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 5, characterized in that: After RH vacuum refining is completed, the Fe-RE alloy wire is inserted into the bottom of the ladle at a speed of 2m / s to 4m / s.

7. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 6, characterized in that: After RH vacuum refining, the temperature of the molten steel is controlled at 1550℃~1600℃, and the Fe-RE alloy wire is fed. At the same time, the argon flow rate at the bottom of the ladle is 0.3Nm 3 / min·t~0.6Nm 3 / min·t.

8. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 4, characterized in that: The perforation temperature is 1150°C to 1250°C, the rolling temperature is 1000°C to 1100°C, and the micro-tension reducing temperature is 800°C to 900°C; and / or The water cooling has a cooling rate of 15°C / s to 30°C / s, and the water cooling temperature is 500°C to 600°C.

9. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 4, characterized in that: The tempering heat treatment process includes the following steps: heating the seamless steel pipe to 660° C. to 700° C. and keeping the temperature, and air cooling.

10. The method for preparing a low-alloy high-strength hydrogen embrittlement resistant pipe according to claim 9, characterized in that: In the tempering heat treatment process, the seamless steel pipe is kept at 660° C. to 700° C. for 10 minutes to 15 minutes.

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