A production method for fatigue-resistant steel plates for hydrogen pipelines

Abstract

The present invention discloses a fatigue-resistant steel plate for hydrogen pipeline and a production method thereof. The chemical composition and weight percentage of the steel plate are: C: 0.05-0.10%, Si: 0.20-0.30%, Mn: 1.00-1.30%, Cr: 0.15-0.35%, Nb+V+Ti: 0.05-0.15%, P≤0.015%, S≤0.010%, and the balance is Fe and inevitable impurity elements; the production method comprises the steps of steel billet heating, rolling, stacking, and tempering heat treatment. The fatigue-resistant steel plate for hydrogen pipeline provided by the present invention is a ferrite+pearlite dual-phase structure, the steel plate structure is uniform, and has good fatigue resistance under hydrogen pressure environment.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen pipeline preparation, and in particular relates to a production method of a fatigue-resistant steel plate for hydrogen pipelines. Background Art

[0002] As awareness of environmental protection and resource conservation continues to grow, countries are shifting their research focus to new energy sources that can replace traditional oil and natural gas, among which hydrogen plays an important role. The product of hydrogen combustion is water, which does not produce pollution or greenhouse effect, and produces the highest energy after combustion. It is widely used in various fields such as civil life, petrochemicals, and automobile manufacturing, and will become the clean energy with the largest share in the 21st century.

[0003] For large-scale, long-distance transportation of gaseous hydrogen, high-pressure pipeline transportation has the advantages of high efficiency and low cost. However, in recent years, there have been many fires and explosions caused by hydrogen leaks in China. The safety of high-pressure pipeline transportation has become a common challenge faced by many scholars. Hydrogen safety is the basis for the sustainable development of hydrogen energy. Due to the inherent properties of the gas in the pipeline and the influence of the start and stop of the compressor, pressure fluctuations are inevitable inside the pipeline. The periodic changes in pressure cause the pipeline to bear cyclic loads.

[0004] Therefore, hydrogen pipelines with excellent anti-fatigue performance under a certain hydrogen pressure are an important link in ensuring the safe and smooth operation of high-pressure hydrogen transmission. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a fatigue-resistant steel plate for hydrogen pipeline and a production method thereof. The steel plate has uniform structure and good fatigue resistance under 2.4MPa hydrogen pressure.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A fatigue-resistant steel plate for hydrogen pipelines, whose chemical composition and weight percentage are: C: 0.05-0.10%, Si: 0.20-0.30%, Mn: 1.00-1.30%, Cr: 0.15-0.35%, Nb+V+Ti: 0.05-0.15%, P≤0.015%, S≤0.010%, and the balance is Fe and unavoidable impurity elements.

[0008] Furthermore, the microstructure of the fatigue-resistant hydrogen pipeline steel plate of the present invention is a ferrite+pearlite dual-phase structure.

[0009] Furthermore, the fatigue crack growth threshold value △K of the fatigue-resistant hydrogen pipeline steel plate of the present invention in air and 2.4MPa hydrogen pressure is th 18~20MPa▪m 1 / 2, and the loss rate of the threshold value of hydrogen pressure fatigue crack growth under hydrogen pressure is ≤10%.

[0010] The production method of the fatigue-resistant hydrogen pipeline steel plate of the present invention comprises the steps of heating the steel billet, rolling, stacking and tempering.

[0011] Furthermore, in the steel billet heating process of the present invention, the smelted steel ingot is heated in a regenerative heating furnace, the furnace gas temperature in the preheating section is 750-850°C, the furnace gas temperature in the heating section is 900-1100°C, the furnace gas temperature in the soaking section is 1150-1250°C, and the steel billet is in the furnace for 180-240 minutes. The heating process before hot rolling can fully diffuse and dissolve the alloy elements in the billet, make the steel structure uniform, and reduce the rolling resistance of hydrogen pipeline steel in the subsequent rolling process.

[0012] Furthermore, the steel billet rolling process of the present invention adopts multi-pass hot rolling to finally roll the steel billet into a slab with a thickness of 14 to 18 mm, controls the final rolling temperature to be 850 to 870° C., and cools the steel billet to 350 to 400° C. in air.

[0013] Furthermore, in the steel plate stacking process of the present invention, the hot-rolled steel plates cooled to 350-400° C. are stacked. Studies have shown that diffusible hydrogen in metal materials can cause hydrogen embrittlement and is reversible. Hydrogen that escapes from steel at a temperature below 300° C. is defined as diffusible hydrogen. Stacking can reduce the risk of hydrogen embrittlement of steel. In order to save costs, the stacking time is designed to be 15-20 hours.

[0014] Furthermore, in the tempering process of the present invention, the tempering temperature is 450-500° C., the temperature is kept for 30-40 minutes, and the steel is air-cooled to room temperature to obtain a ferrite + pearlite structure with fine and uniform structure and good fatigue resistance under a hydrogen pressure of 2.4 MPa.

[0015] The beneficial effects of adopting the above technical solution are:

[0016] 1. The hydrogen pipeline steel provided by the present invention mainly has C, Si, Mn and Cr as main chemical components. It is formed by adding trace alloy elements and hot rolling, has low equipment requirements and simple production process.

[0017] 2. The steel for hydrogen pipeline provided by the present invention obtains ferrite + pearlite structure after tempering, the structure is uniform, and the fatigue resistance is excellent under 2.4MPa hydrogen pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the metallographic structure of the steel plate in Example 1. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution 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 used to limit the present invention. Example 1

[0020] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. Its chemical composition and weight percentage obtained by direct reading spectrometer are: C: 0.05%, Si: 0.20%, Mn: 1.0%, Cr: 0.15%, V+Nb+Ti: 0.05%, P: 0.008%, S: 0.009%, and the balance is Fe and unavoidable impurities; its production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0021] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of the preheating section at 750°C, the furnace gas temperature of the heating section at 900°C, the furnace gas temperature of the soaking section at 1150°C, and the billet in the furnace time at 180 min.

[0022] Rolling process: The heated slab is hot rolled into a 14 mm thick slab through multiple passes, with a final rolling temperature of 850°C, and then naturally cooled in air to 350°C.

[0023] Stacking process: The hot-rolled steel plates cooled to 350°C are stacked for 18 hours.

[0024] Tempering process: The stacked steel plates are tempered at a temperature of 450°C, a holding time of 30 minutes, and air-cooled to room temperature to obtain a ferrite + pearlite structure with a structure morphology such as Figure 1 The tissue morphologies obtained in each embodiment are the same and will not be presented one by one. Example 2

[0025] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. The chemical composition and weight percentage thereof are obtained by direct reading spectrometer: C: 0.06%, Si: 0.22%, Mn: 1.15%, Cr: 0.20%, V+Nb+Ti: 0.08%, P: 0.007%, S: 0.007%, and the balance is Fe and unavoidable impurities; the production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0026] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of 780°C in the preheating section, 950°C in the heating section, 1180°C in the soaking section, and the billet in the furnace time of 200 minutes.

[0027] Rolling process: The heated slab is hot rolled into a 14.7 mm thick slab through multiple passes, with a final rolling temperature of 855°C, and then naturally cooled in air to 360°C.

[0028] Stacking process: The hot-rolled steel plates cooled to 360°C are stacked for 17 hours.

[0029] Tempering process: The stacked steel plates are tempered at a temperature of 465°C, a holding time of 40 minutes, and air-cooled to room temperature to finally obtain a ferrite + pearlite structure. Example 3

[0030] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. The chemical composition and weight percentage thereof are obtained by direct reading spectrometer: C: 0.08%, Si: 0.24%, Mn: 1.17%, Cr: 0.25%, V+Nb+Ti: 0.11%, P: 0.010%, S: 0.010%, and the balance is Fe and unavoidable impurities; the production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0031] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of the preheating section being 800°C, the furnace gas temperature of the heating section being 1000°C, the furnace gas temperature of the soaking section being 1200°C, and the billet being in the furnace for 210 minutes.

[0032] Rolling process: The heated slab is hot rolled into a 15.5 mm thick slab through multiple passes, with a final rolling temperature of 862°C, and then naturally cooled in air to 372°C.

[0033] Stacking process: The hot-rolled steel plates cooled to 372°C are stacked for 15 hours.

[0034] Tempering process: The stacked steel plates are tempered at a tempering heating temperature of 470°C, a holding time of 35 minutes, and air-cooled to room temperature to finally obtain a ferrite + pearlite structure. Example 4

[0035] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. The chemical composition and weight percentage thereof are obtained by direct reading spectrometer: C: 0.07%, Si: 0.27%, Mn: 1.23%, Cr: 0.28%, V+Nb+Ti: 0.12%, P: 0.012%, S: 0.006%, and the remainder is Fe and unavoidable impurities; the production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0036] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of the preheating section being 830°C, the furnace gas temperature of the heating section being 1050°C, the furnace gas temperature of the soaking section being 1220°C, and the billet being in the furnace for 220 minutes.

[0037] Rolling process: The heated slab is hot rolled into a 16.3 mm thick slab through multiple passes, with a final rolling temperature of 866°C, and then naturally cooled in air to 385°C.

[0038] Stacking process: The hot-rolled steel plates cooled to 385°C are stacked for 19 hours.

[0039] Tempering process: The stacked steel plates are tempered at a tempering heating temperature of 485°C, a holding time of 38 minutes, and air-cooled to room temperature to finally obtain a ferrite + pearlite structure. Example 5

[0040] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. The chemical composition and weight percentage thereof are obtained by direct reading spectrometer: C: 0.09%, Si: 0.28%, Mn: 1.26%, Cr: 0.31%, V+Nb+Ti: 0.14%, P: 0.009%, S: 0.005%, and the balance is Fe and unavoidable impurities; the production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0041] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of the preheating section being 840°C, the furnace gas temperature of the heating section being 1080°C, the furnace gas temperature of the soaking section being 1230°C, and the billet being in the furnace for 230 minutes.

[0042] Rolling process: The heated slab is hot rolled into a 17.5 mm thick slab through multiple passes, with a final rolling temperature of 858°C, and then naturally cooled in air to 390°C.

[0043] Stacking process: The hot-rolled steel plates cooled to 390°C are stacked for 16 hours.

[0044] Tempering process: The stacked steel plates are tempered at a tempering heating temperature of 490°C for 35 minutes and air-cooled to room temperature to obtain a ferrite + pearlite structure. Example 6

[0045] A fatigue-resistant steel plate for hydrogen pipeline is smelted in a 50kg vacuum furnace and cast into a steel ingot. Its chemical composition and weight percentage obtained by direct reading spectrometer are: C: 0.10%, Si: 0.30%, Mn: 1.30%, Cr: 0.35%, V+Nb+Ti: 0.15%, P: 0.010%, S: 0.007%, and the balance is Fe and unavoidable impurities; its production process includes billet heating, rolling, stacking, and tempering processes, as follows:

[0046] Billet heating process: The steel ingot is heated in a regenerative heating furnace, with the furnace gas temperature of the preheating section at 850°C, the furnace gas temperature of the heating section at 1100°C, the furnace gas temperature of the soaking section at 1250°C, and the billet in the furnace time of 240 minutes.

[0047] Rolling process: The heated slab is hot rolled into 18 mm thick slab through multiple passes, with the final rolling temperature being 870°C, and then naturally cooled in air to 400°C.

[0048] Stacking process: The hot-rolled steel plates cooled to 400°C are stacked for 20 hours.

[0049] Tempering process: The stacked steel plates are tempered at a temperature of 500°C, a holding time of 40 minutes, and air-cooled to room temperature to finally obtain a ferrite + pearlite structure.

[0050] The fatigue resistance of the steel in each embodiment was tested according to GB / T6398-2017 "Metallic Material Fatigue Test Fatigue Crack Propagation Method". A high-frequency fatigue testing machine of model QBG-50 was used to pre-crack the CT specimen in the air. The pre-crack length was 1.5 mm, the specimen loading frequency was 20 Hz, the load range was 8000-10000 N, and the loading load ratio was R=0.1. The fatigue crack propagation threshold value measured in the air at room temperature was recorded as △K th-0 The sample was kept under 2.4 MPa H2 environment for 24 h and then subjected to fatigue crack growth test. The fatigue crack growth threshold value measured under hydrogen pressure was recorded as △K th-H , the results are shown in Table 1.

[0051]

Claims

1. A fatigue-resistant steel plate for hydrogen pipeline, characterized in that: The chemical composition of the steel plate and its weight percentage are: C: 0.05-0.10%, Si: 0.20-0.30%, Mn: 1.00-1.30%, Cr: 0.15-0.35%, Nb+V+Ti: 0.05-0.15%, P≤0.015%, S≤0.010%, and the balance is Fe and unavoidable impurity elements; The fatigue crack growth threshold value △K of the steel plate in air and 2.4MPa hydrogen pressure th 18~20MPa▪m 1 / 2 , the fatigue crack growth threshold loss rate under hydrogen pressure is ≤10%; The production method of the steel plate includes the steps of heating, rolling, stacking and tempering the steel billet; In the billet heating process, the billet is heated in a regenerative heating furnace, the furnace gas temperature in the preheating section is 750-850°C, the furnace gas temperature in the heating section is 900-1100°C, the furnace gas temperature in the soaking section is 1150-1250°C, and the billet is in the furnace for 180-240 minutes; The rolling process is to roll the heated steel ingot into a slab with a thickness of 14 to 18 mm through multiple hot rolling passes, control the final rolling temperature to be 850 to 870° C., and cool it to 350 to 400° C. in air; In the stacking process, the steel plates air-cooled to 350-400° C. after hot rolling are stacked for 15-20 hours; The tempering process is to perform a tempering heat treatment on the stacked steel plates, the tempering temperature is 450-500° C., and the tempering time is 30-40 minutes.

2. The fatigue-resistant steel plate for hydrogen pipeline according to claim 1, characterized in that: The microstructure of the steel plate is a ferrite+pearlite dual-phase structure.

3. A method for producing the fatigue-resistant hydrogen pipeline steel plate according to any one of claims 1 to 2, comprising the steps of heating, rolling, stacking and tempering the steel billet; In the stacking process, the steel plates air-cooled to 350-400° C. after hot rolling are stacked for 15-20 hours; The tempering process is to perform a tempering heat treatment on the stacked steel plates, the tempering temperature is 450-500° C., and the tempering time is 30-40 minutes.

4. The method for producing a fatigue-resistant steel plate for hydrogen pipeline according to claim 3, characterized in that: In the billet heating process, the billet is heated in a regenerative heating furnace, the furnace gas temperature in the preheating section is 750-850°C, the furnace gas temperature in the heating section is 900-1100°C, the furnace gas temperature in the soaking section is 1150-1250°C, and the billet is in the furnace for 180-240 minutes.

5. The method for producing a fatigue-resistant steel plate for hydrogen pipeline according to claim 3, characterized in that: In the rolling process, the heated steel ingot is rolled into a slab with a thickness of 14 to 18 mm through multiple hot rolling steps, the final rolling temperature is controlled to be 850 to 870° C., and the slab is cooled to 350 to 400° C. in air.

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