CN116765166A - Manufacturing method of seamless steel tube for large-caliber thin-wall alloy high-pressure gas cylinder with diameter-wall ratio not less than 50 - Google Patents
Manufacturing method of seamless steel tube for large-caliber thin-wall alloy high-pressure gas cylinder with diameter-wall ratio not less than 50 Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 127
- 239000010959 steel Substances 0.000 title claims abstract description 127
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- 229910045601 alloy Inorganic materials 0.000 title claims abstract description 25
- 239000000956 alloy Substances 0.000 title claims abstract description 25
- 238000010438 heat treatment Methods 0.000 claims abstract description 61
- 238000010622 cold drawing Methods 0.000 claims abstract description 59
- 238000005096 rolling process Methods 0.000 claims abstract description 27
- 238000009749 continuous casting Methods 0.000 claims abstract description 23
- 239000002994 raw material Substances 0.000 claims abstract description 14
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- 238000007127 saponification reaction Methods 0.000 claims abstract description 13
- 238000007689 inspection Methods 0.000 claims abstract description 12
- 238000002360 preparation method Methods 0.000 claims abstract description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 10
- 239000010439 graphite Substances 0.000 claims abstract description 10
- 238000005554 pickling Methods 0.000 claims abstract description 9
- 238000009659 non-destructive testing Methods 0.000 claims abstract description 8
- 239000011248 coating agent Substances 0.000 claims abstract description 6
- 238000000576 coating method Methods 0.000 claims abstract description 6
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- 238000004513 sizing Methods 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 41
- 230000008569 process Effects 0.000 claims description 27
- 238000003723 Smelting Methods 0.000 claims description 20
- 238000005406 washing Methods 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 238000002791 soaking Methods 0.000 claims description 14
- 238000009849 vacuum degassing Methods 0.000 claims description 12
- 239000002253 acid Substances 0.000 claims description 11
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 239000011575 calcium Substances 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 6
- 238000007670 refining Methods 0.000 claims description 6
- 229910000851 Alloy steel Inorganic materials 0.000 claims description 5
- 238000010079 rubber tapping Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 16
- 238000000137 annealing Methods 0.000 description 9
- 229910052742 iron Inorganic materials 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- 238000005098 hot rolling Methods 0.000 description 6
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Abstract
The application discloses a manufacturing method of a seamless steel tube for a large-caliber thin-wall alloy high-pressure gas cylinder with a diameter-wall ratio of more than or equal to 50. The preparation method comprises the following steps: the continuous casting round billet is used as a raw material, and the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is obtained by sequentially carrying out annular furnace heating, perforation, continuous rolling, stepping furnace heating, sizing, primary straightening, sampling inspection, nondestructive testing, primary pickling, graphite coating, hot expansion, secondary pickling, phosphating, saponification, primary cold drawing, induction coil heating and secondary straightening on the continuous casting round billet. Compared with the prior art, the preparation method has the advantages of high production efficiency and low production cost; the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder, which is prepared by the application, has the advantages of high dimensional accuracy, good surface quality, high heat treatment strength after the gas cylinder is manufactured, and good low-temperature impact toughness.
Description
Technical Field
The application relates to the field of seamless steel tube manufacturing, in particular to a manufacturing method of a seamless steel tube for a large-caliber thin-wall alloy high-pressure gas cylinder with a diameter-wall ratio of more than or equal to 50.
Background
At present, a seamless steel tube for domestic CNG gas cylinders (for large-caliber thin-wall high-pressure gas cylinders) is developed towards the directions of large caliber and thin wall so as to improve the volume of the steel cylinder and reduce the weight of the gas cylinder. The common bottle materials mainly comprise alloy steels 30CrMo, 35CrMo and 34CrMo4, and commonly used specifications comprise phi 356 multiplied by 4.5mm, phi 406 multiplied by 5.5mm, phi 426 multiplied by 5.9mm and the like. The domestic continuous rolling tube unit can only produce thin-wall tubes with the ratio of the outer diameter to the wall thickness not exceeding 45, and the specifications exceed the production technical limit of the existing continuous rolling tubes, so that the continuous rolling tube unit is usually produced by adopting the technological processes of hot rolling tube billet, hot expansion, annealing and cold drawing, and part of specifications also need secondary annealing and secondary cold drawing, and have the problems of long production process, high cost and long delivery cycle. For example, CN103316935a discloses a cold drawing method for a large-diameter gas cylinder pipe with a diameter of 500mm or more, but the steel pipe has a thick wall thickness, and requires pretreatment processes such as shot blasting and annealing, which has problems of long flow and high cost; CN102962273a discloses a method for manufacturing a cold drawn ultrathin seamless steel tube for a fully-wound glass fiber gas cylinder for a vehicle, in which the secondary cold drawing of the steel tube requires an intermediate annealing treatment, thus increasing the production period and the manufacturing cost.
Disclosure of Invention
The application aims to provide a manufacturing method of a seamless steel tube for a large-caliber thin-wall alloy high-pressure gas cylinder with a diameter-wall ratio of more than or equal to 50, which aims to solve the technical problems of long production flow and high cost in the preparation process of the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder in the prior art.
In order to achieve the above object, according to one aspect of the present application, there is provided a method for producing a seamless steel pipe for a high pressure gas cylinder of a large caliber thin wall alloy having a radial wall ratio of not less than 50. The preparation method comprises the following steps: the continuous casting round billet is used as a raw material, and the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is obtained by sequentially carrying out annular furnace heating, perforation, continuous rolling, stepping furnace heating, sizing, primary straightening, sampling inspection, nondestructive testing, primary pickling, graphite coating, hot expansion, secondary pickling, phosphating, saponification, primary cold drawing, induction coil heating and secondary straightening on the continuous casting round billet.
Further, continuous rolling is carried out on the continuous casting round billet, and the final rolling temperature is controlled to be 790-820 ℃.
Further, the alloy steel of the continuous casting round billet is 30CrMo, 35CrMo or 34CrMo4.
Further, the preparation method also comprises a step of rechecking after the second straightening; optionally, a second cold drawing step is further included between the induction coil heating and the second straightening.
Further, the continuous casting round billet is prepared by adopting electric furnace smelting, external refining, vacuum degassing and arc continuous casting processes, the smelting tapping temperature is not less than 1620 ℃, the vacuum holding time is not less than 15min, the soft blowing time is not less than 10min, aluminum wires are added in the smelting process, and pure calcium wires are fed after vacuum degassing and emptying.
Further, the annular furnace heating comprises three processes of preheating, heating and soaking, wherein the preheating temperature is 790-830 ℃ and the preheating time is 50-55 min; heating at 990-1300 deg.c for 50-60 min; the soaking temperature is 1250-1290 ℃ and the soaking time is 80-85 min.
Further, the hot expansion temperature is 730-770 ℃, and the pushing speed is controlled at 300-400 mm/min.
Further, the steel pipe is subjected to first cold drawing on a hydraulic cold drawing machine, and the wall reduction amount of the steel pipe is not more than 2.2mm; if the second cold drawing is needed, the steel pipe after the first cold drawing is heated by an intermediate frequency hot expansion coil, the heating temperature of the coil is set to 780-820 ℃, the advancing speed of the steel pipe is slower than that of the hot expansion coil, the advancing speed is controlled to be 180-220 mm/min, the steel pipe is cooled and then saponified again for the second cold drawing, and the wall reduction amount of the cold drawing is less than or equal to 1.3mm, so that the finished steel pipe is obtained.
Further, the first acid washing comprises washing with sulfuric acid with a concentration of 15-20%; the second acid washing comprises washing with sulfuric acid with concentration of 15-20%; preferably, the temperature of the induction coil is 780-820 ℃; preferably, the thermal expansion temperature is 730 ℃ to 770 ℃.
According to the other aspect of the application, the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder, the diameter-wall ratio of which is not less than 50, is prepared by the preparation method of the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder, and the diameter-wall ratio of which is not less than 50, is provided.
By applying the technical scheme of the application, the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is prepared and is mainly used for manufacturing CNG gas cylinders and the like; the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder, which is prepared by the application, has the advantages of high dimensional accuracy, good surface quality, high heat treatment strength after the gas cylinder is manufactured, and good low-temperature impact toughness.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The present application will be described in detail with reference to examples.
In the present application, the radial wall ratio is not less than 50, and the radial wall ratio is not less than 50.
Aiming at the technical problems of long production flow and high cost of the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder in the prior art, according to an exemplary embodiment of the application, a manufacturing method of the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is provided. The preparation method comprises the following steps: the continuous casting round billet is used as a raw material, and the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is obtained by sequentially carrying out annular furnace heating, perforation, continuous rolling, stepping furnace heating, sizing, primary straightening, sampling inspection, nondestructive testing, primary pickling, graphite coating, hot expansion, secondary pickling, phosphating, saponification, primary cold drawing, induction coil heating and secondary straightening on the continuous casting round billet.
By applying the technical scheme of the application, the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is prepared and is mainly used for manufacturing CNG gas cylinders and the like; the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder, which is prepared by the application, has the advantages of high dimensional accuracy, good surface quality, high heat treatment strength after the gas cylinder is manufactured, and good low-temperature impact toughness.
Preferably, the rolled tube adopts conical perforation, then the process modes of tube rolling, heating by a stepping furnace, sizing and the like are adopted, the heating temperature and advancing rhythm of the stepping furnace are adjusted, the final rolling temperature of the steel tube is controlled to 790-820 ℃, the structure form is improved, the hardness of the steel tube is reduced, the dimensional accuracy and the surface quality of the steel tube are ensured, and then the raw material capillary tube is manufactured by the working procedures of straightening, nondestructive testing, manual testing and the like. The pipe blank is heated in a heating furnace, so as to improve the plasticity of the steel, reduce the deformation resistance to meet the requirements of hot working conditions of working procedures such as perforation, pipe rolling and the like, improve the structural performance of the steel, homogenize the structure of the steel and help to eliminate harmful gases, inclusions and the like in the steel. The rolling pipe adopts a conical roller perforation and multi-frame longitudinal rolling mode, the deformation is reasonably distributed in each working procedure, the defects of cracks and the like are effectively avoided, and the dimensional accuracy of the steel pipe is ensured. The continuous casting round billet is prepared by adopting electric furnace smelting, external refining, vacuum degassing and arc continuous casting processes (EAF+LF+VD+CC), the smelting tapping temperature is more than or equal to 1620 ℃, the vacuum holding time is more than or equal to 15min, the soft blowing time is more than or equal to 10min, aluminum wires are added in the smelting process, and pure calcium wires are fed after vacuum degassing and emptying. The billet smelting adopts high-quality molten iron (the high-quality molten iron is molten iron with As less than or equal to 0.006 percent and Sn less than or equal to 0.004 percent), the balance adopts scrap steel for supplementation, aluminum wires are added in the smelting process, and pure calcium wires are fed after VD breaks the air to remove impurities in the molten steel, vacuum degassing is carried out, argon blowing protection is carried out during casting, and the purity of the steel is improved. In one embodiment of the application, the alloy steel of the continuous casting round billet is 30CrMo, 35CrMo or 34CrMo4.
According to an exemplary embodiment of the present application, the second straightening further comprises a rechecking step; optionally, a second cold drawing step is further included between the induction coil heating and the second straightening. In one embodiment of the application, the first straightening is a production process of hot rolling, and six-roller straightening is performed; and straightening, pressing and straightening the cold drawn finished pipe for the second time.
According to an exemplary embodiment of the present application, the annular furnace heating is used for heating the tube blank, and the annular furnace heating comprises three processes of preheating, heating and soaking, wherein the preheating temperature is 790-830 ℃ and the preheating time is 50-55 min; heating at 990-1300 deg.c for 50-60 min; the soaking temperature is 1250-1290 ℃ and the soaking time is 80-85 min. The heating temperature and time of each section are reasonably distributed so as to prevent uneven heating and heating defects.
After the primary acid washing of the raw material capillary tube, the inner wall of the raw material capillary tube is coated with a graphite lubricant, and then the raw material capillary tube is thermally expanded into a cold drawn capillary tube on an intermediate frequency induction thermal expander, wherein the thermal expansion temperature of the steel tube is 730-770 ℃, and the pushing speed is controlled at 300-400 mm/min. Proper temperature and speed parameters are adopted to ensure the quality of the steel pipe after thermal expansion deformation. Wherein the first acid washing comprises washing with sulfuric acid with a concentration of 15-20% to remove iron scale.
Grinding to remove graphite adhered to the inner surface of the hot-expanded steel pipe, carrying out acid washing for the second time, and then carrying out phosphating and saponification treatment. Wherein the second acid washing comprises washing with sulfuric acid with concentration of 15-20% to remove iron scale.
Performing primary cold drawing on the steel tube on a hydraulic cold drawing machine, wherein the wall reducing amount principle of the steel tube is not more than 2.2mm; if the second cold drawing is needed, the steel pipe after the first cold drawing is heated by an intermediate frequency hot-expanding coil, the heating temperature of the coil is set to 780-820 ℃, the advancing speed of the steel pipe is slower than that of the hot expanding (namely, the speed of the steel pipe passing through an induction coil is slower than that of the steel pipe in the hot-expanding process, a certain heat preservation effect is achieved), the temperature is controlled to be 180-220 mm/min, the steel pipe is cooled and then saponified again for the second cold drawing, and the wall-reducing amount of the cold drawing is less than or equal to 1.3mm, so that the finished steel pipe is obtained. The technological parameters are controlled in such a way as to eliminate the first cold drawing work hardening, and the improvement of plasticity is convenient for the second cold drawing.
Straightening, nondestructive testing and checking are carried out on the finished steel pipes after cold drawing, and finally packaging and warehousing are carried out.
The application has the technical characteristics and advantages that:
when the CrMo steel large-caliber thin-wall alloy high-pressure gas cylinder pipe is produced by hot rolling, a large amount of bainite structure can be obtained by air cooling due to good hardenability of steel types, the strength and hardness of the hot rolled steel pipe are high, the elongation is low, the metallographic structure is basically bainite and a small amount of ferrite, and cold drawing processing can be performed after the hardness is reduced by heat treatment. When the hot-rolled steel pipe is hot-rolled, the final rolling temperature of the steel pipe is controlled to be 790-820 ℃, the structure morphology is improved to obtain ferrite and pearlite structure, the hardness of the hot-rolled capillary is reduced to be less than or equal to 200HBW, the hot-rolled capillary is very beneficial to the first cold drawing process after hot expansion, the hot expansion temperature can be reduced, the pushing speed of the steel pipe during hot expansion is improved, the production efficiency is improved, and the energy consumption is reduced.
For the production specification requiring secondary cold drawing, after the primary cold drawing is finished, the steel pipe is heated by a hot-expanding coil, the advancing speed is properly controlled to keep the temperature, and the work hardening of the primary cold drawing is eliminated. The steel pipe does not need to enter a furnace for annealing, so that energy consumption is saved, and deformation and oval outer diameter of the thin-wall steel pipe in the annealing process can be avoided, so that the second cold drawing is difficult.
In a typical embodiment of the application, the related large-caliber thin-wall high-pressure gas cylinder tube adopts the technological process of EAF+LF+VD+CC (electric furnace smelting, external refining, vacuum degassing and arc continuous casting) to produce 30CrMo, 35CrMo, 34CrMo4 and other alloy steel brands of continuous casting round billets, the steel tube is hot-rolled into a hollow billet by a continuous rolling process, the final rolling temperature of the steel tube is controlled, the structure form is improved, the rigidity of the hollow billet is reduced, and the hollow billet is finally molded by the manners of hot expansion and cold drawing of the hollow billet, so that the annealing procedure required by conventional cold drawing is omitted in the technological process, and the production period and the cost are reduced. The alloy steel gas cylinder tube component of the application strictly controls the content of harmful elements such As P, S, as, sn and the like (As is less than or equal to 0.010%, sn is less than or equal to 0.010%, sb is less than or equal to 0.010%, pb is less than or equal to 0.010%, bi is less than or equal to 0.010%, P is less than or equal to 0.015%, S is less than or equal to 0.005%), and the steel is pure; the control precision of the outer diameter and the wall thickness of the hot rolled capillary tube is high, cold drawing is performed after hot expansion, the surface quality of the steel tube is good, the dimensional precision is high, and the production efficiency is greatly improved.
The advantageous effects of the present application will be further described below with reference to examples.
Example 1
The steel pipe with the brand of 30CrMo and the specification of phi 416 multiplied by 4.1mm comprises the following components in mass percent: 0.28 to 0.32 percent of C, 0.40 to 0.70 percent of Mn, 0.17 to 0.35 percent of Si, 0.8 to 1.10 percent of Cr, less than or equal to 0.30 percent of Ni, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.15 to 0.25 percent of Mo and less than or equal to 0.20 percent of Cu; the balance being Fe and impurities.
The tube blank smelting process flow comprises the following steps:
electric furnace smelting, external refining, vacuum degassing and arc continuous casting. The billet smelting adopts high-quality molten iron with As less than or equal to 0.006 percent and Sn less than or equal to 0.004 percent, the balance adopts high-quality scrap steel with As less than or equal to 0.006 percent and Sn less than or equal to 0.004 percent to be supplemented, 80-160 m of aluminum wires and 160-200 m of pure calcium wires are added in the smelting process to remove impurities in molten steel, vacuum degassing is carried out, argon blowing protection is carried out during casting, and the purity of the steel is improved.
The pipe rolling process flow comprises the following steps:
blank inspection, sawing and blanking, annular furnace heating, conical roller perforation, continuous rolling, step furnace reheating, high-pressure water descaling (descaling, namely oxide skin), tension reducing, cooling by a cooling bed, pipe cutting, sampling and detecting physical and chemical properties, straightening, manual inspection, nondestructive inspection, manual inspection, word spraying, packaging and warehousing
Blank heating process parameters (annular furnace heating): preheating section 810 ℃, heating section 1080 ℃, heating section 1200 ℃, heating section 1280 ℃, heating section 1300 ℃, heating section 1295 ℃, soaking section 1290 ℃, blank outer diameter of phi 330mm, tube blank length of 2340mm and total heating time of >180min.
Perforation process parameters: the roll spacing is 290mm, the guide disc spacing is 320mm, the plug protrusion is 114mm, and the perforated capillary size is phi 419 multiplied by 21.5 multiplied by 7500mm.
Pipe rolling process parameters: the diameter of the core rod is 348.4mm, and the size of the rolled pierced billet is phi 356 multiplied by 7.8 multiplied by 23000mm.
The pierced billet is heated by a stepping furnace and then sized to obtain a hot rolled finished pipe phi 325 multiplied by 8.2mm, the soaking section temperature of the stepping furnace is set to 910 ℃, the finish rolling temperature of the steel pipe is controlled to 800 ℃, the hot rolled steel pipe structure is improved to obtain ferrite and pearlite, the hardness of the steel pipe is reduced to be less than or equal to 200HBW, the elongation is increased to be more than or equal to 27%, and the plasticity of the steel pipe is improved.
And (3) carrying out first acid washing (15-20% sulfuric acid) on the raw material blank pipe obtained by hot rolling, coating a graphite lubricant on the inner wall of the raw material blank pipe, then carrying out hot expansion on the raw material blank pipe on an intermediate frequency induction hot expander, wherein the hot expansion temperature is 750 ℃, the hot expansion pushing speed is controlled at 320mm/min, and the average wall thickness of the hot expanded steel pipe is about 7.6mm.
Grinding to remove graphite adhered to the inner surface of the hot-expanded steel pipe, and then carrying out second acid washing (15-20% sulfuric acid) to clean the surface oxides and the like; then the steel pipe is subjected to phosphating treatment, the phosphating temperature is 64 ℃, and the phosphating time is 38 minutes; and (3) carrying out saponification treatment on the phosphated steel pipe, wherein the saponification temperature is 55 ℃, and the saponification time is 20 minutes.
After saponification is completed, the steel pipe is subjected to first cold drawing on a hydraulic cold drawing machine, the wall reducing amount of the first cold drawing is controlled to be 1.8-2.0 mm, and the wall reducing rate of the single cold drawing is 26.32%; the steel pipe is heated by an intermediate frequency hot-expanding coil after the first cold drawing is finished, the coil heating temperature is set to 800 ℃, the advancing speed is 210mm/min, the steel pipe is cooled and saponified again to carry out the second cold drawing to obtain the finished steel pipe size, the wall reducing amount of the second cold drawing is 1.0-1.2 mm, and the wall reducing rate of the single cold drawing is 21.43%. The cold drawing deformation of the two passes is distributed reasonably, and the phenomena of drawing crack and even drawing breakage caused by overlarge wall reduction of the steel pipe are avoided.
Straightening the steel pipes with out-of-tolerance straightness, carrying out nondestructive testing on the steel pipes one by one, and carrying out mark spraying, packaging and warehousing after the steel pipes are qualified.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 1
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 1 | Φ416×4.1mm | 416.2～416.7 | 4.2～4.8 | 0.8 |
TABLE 2
The detection method of the technical parameters refers to national standards, and specifically comprises the following steps:
tensile strength: GB/T228.1;
yield strength: GB/T228.1;
elongation percentage: GB/T228.1;
-50 ℃ longitudinal impact value: GB/T229;
-50 ℃ transverse impact value: GB/T229.
Example 2
The steel pipe with the brand of 34CrMo4 and the specification of phi 406 multiplied by 5.4mm comprises the following components in mass percent: 0.30 to 0.37 percent of C, 0.60 to 0.90 percent of Mn, 0.15 to 0.35 percent of Si, 0.9 to 1.20 percent of Cr, less than or equal to 0.30 percent of Ni, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.15 to 0.30 percent of Mo, and less than or equal to 0.20 percent of Cu; the balance being Fe and impurities.
The tube blank smelting process flow comprises the following steps:
electric furnace smelting, external refining, vacuum degassing and arc continuous casting. The steel billet smelting adopts high-quality molten iron, the balance of high-quality scrap steel is supplemented, 80-160 m of aluminum wires and 160-200 m of pure calcium wires are added in the smelting process to remove impurities in the molten steel, vacuum degassing is carried out, argon blowing protection is carried out in casting, and the purity of the steel is improved.
The pipe rolling process flow comprises the following steps:
blank inspection, sawing and blanking, annular furnace heating, conical roller perforation, continuous rolling, step furnace reheating, high-pressure water descaling, tension reducing, cooling by a cooling bed, pipe cutting, sampling and detecting physical and chemical properties, straightening, manual inspection, nondestructive inspection, manual inspection, word spraying, packaging and warehousing
Blank heating process parameters: preheating section 815 ℃, heating section 1082 ℃, heating section 1210 ℃, heating section 1285 ℃, heating section 1300 ℃, heating section 1293 ℃, soaking section 1290 ℃, blank outer diameter of phi 330mm, tube blank length of 2300mm, total heating time >180min.
Perforation process parameters: the roll spacing is 290mm, the guide disc spacing is 320mm, the plug protrusion is 114mm, and the perforated capillary size is phi 419 multiplied by 21.5 multiplied by 7000mm.
Pipe rolling process parameters: the diameter of the core rod is 348.4mm, and the size of the rolled pierced billet is phi 356 multiplied by 7.8 multiplied by 22500mm.
The pierced billet is heated by a stepping furnace and then sized to obtain a hot rolled finished pipe phi 325 multiplied by 8.2mm, the soaking section temperature of the stepping furnace is set to 910 ℃, the finish rolling temperature of the steel pipe is controlled to 800 ℃, the hot rolled steel pipe structure is improved to obtain ferrite and pearlite, the hardness of the steel pipe is reduced to be less than or equal to 200HBW, the elongation is increased to be more than or equal to 27%, and the plasticity of the steel pipe is improved.
And (3) pickling the raw material blank pipe obtained by hot rolling, coating a graphite lubricant on the inner wall of the raw material blank pipe, then performing hot expansion on the inner wall of the raw material blank pipe by using an intermediate frequency induction hot expander, wherein the hot expansion temperature is 760 ℃, the hot expansion pushing speed is controlled to be 310mm/min, and the average wall thickness of the hot-expanded steel pipe is about 7.8mm.
Grinding to remove graphite adhered to the inner surface of the hot-expanded steel pipe, and then carrying out acid washing to clean oxide and the like on the surface; then the steel pipe is subjected to phosphating treatment, the phosphating temperature is 65 ℃, and the phosphating time is 40 minutes; and (3) carrying out saponification treatment on the phosphated steel pipe, wherein the saponification temperature is 55 ℃, and the saponification time is 25 minutes.
After saponification is completed, the steel pipe is subjected to cold drawing on a hydraulic cold drawing machine, the wall reduction amount of the cold drawing is controlled to be 1.8-2.0 mm, and the wall reduction rate of the cold drawing is 24.35%.
Straightening the steel pipes with out-of-tolerance straightness, carrying out nondestructive testing on the steel pipes one by one, and carrying out mark spraying, packaging and warehousing after the steel pipes are qualified.
TABLE 3 Table 3
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 2 | Φ406×5.4mm | 406.2～406.6 | 5.5～6.0 | 0.8 |
TABLE 4 Table 4
Example 3
Substantially the same as in example 1, except that the soaking section temperature of the stepping furnace was set to 920 ℃.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 5
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 4 | Φ416×4.1mm | 416.3～416.8 | 4.3～4.8 | 0.8 |
TABLE 6
Example 4
Substantially the same as in example 1, except that the steel pipe finishing temperature was controlled at 790 ℃.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 7
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 3 | Φ416×4.1mm | 416.3～416.7 | 4.3～4.8 | 0.8 |
TABLE 8
Example 5
Substantially the same as in example 1, except that the steel pipe finishing temperature was controlled at 820 ℃.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 9
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 6 | Φ416×4.1mm | 416.3～416.8 | 4.3～4.8 | 0.8 |
Table 10
Example 6
Essentially the same as in example 1, except that the heat expansion temperature was 730℃and the heat expansion pushing speed was controlled at 300mm/min.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 11
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 7 | Φ416×4.1mm | 416.2～416.8 | 4.3～4.8 | 0.8 |
Table 12
Example 7
Essentially the same as in example 1, except that the thermal expansion temperature was 770℃and the thermal expansion pushing speed was controlled at 400mm/min.
The parameters related to the seamless steel tube prepared by the embodiment are as follows:
TABLE 13
| Examples | Specification/mm | Outer diameter range/mm | Wall thickness range/mm | Straightness mm/m |
| 8 | Φ416×4.1mm | 416.2～416.8 | 4.1～4.8 | 0.8 |
TABLE 14
From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:
1) The final rolling temperature of the steel pipe is controlled to be 790-820 ℃ during hot rolling, the structure morphology is improved to obtain ferrite and pearlite structure, the hardness of the hot rolled capillary is reduced to be less than or equal to 200HBW, the first cold drawing process after hot expansion is very beneficial, the hot expansion temperature can be reduced, the pushing speed of the steel pipe during hot expansion is improved, the production efficiency is improved, and the energy consumption is reduced;
2) For the production specification requiring secondary cold drawing, after the primary cold drawing is finished, heating the steel pipe through a hot-expanding coil, controlling the travelling speed to preserve heat, and eliminating the work hardening of the primary cold drawing; the steel pipe does not need to enter a furnace for annealing, so that on one hand, the energy consumption is saved, and on the other hand, the deformation of the thin-wall steel pipe in the annealing process can be avoided, and the outer diameter is elliptical;
3) Compared with the prior art, the process has the advantages that the production efficiency of hot expansion is greatly improved, the steel pipe does not need to be annealed in a furnace before cold drawing, the production cost is reduced, and the product quality is ensured by combining non-destructive detection and other measures.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A method for manufacturing a seamless steel tube for a large-caliber thin-wall alloy high-pressure gas cylinder with a diameter-wall ratio of more than or equal to 50 is characterized by comprising the following steps:
the continuous casting round billet is adopted as a raw material, and the seamless steel tube for the large-caliber thin-wall alloy high-pressure gas cylinder with the diameter-wall ratio of more than or equal to 50 is obtained by sequentially carrying out annular furnace heating, perforation, continuous rolling, stepping furnace heating, sizing, primary straightening, sampling inspection, nondestructive testing, primary pickling, graphite coating, hot expansion, secondary pickling, phosphating, saponification, primary cold drawing, induction coil heating and secondary straightening on the continuous casting round billet.
2. The method according to claim 1, wherein the continuous casting round billet is subjected to continuous rolling, and the final rolling temperature is controlled to be 790-820 ℃.
3. The method according to claim 1, wherein the alloy steel grade of the continuous casting round billet is 30CrMo, 35CrMo or 34CrMo4.
4. A method of preparation according to any one of claims 1 to 3, characterized in that the method of preparation further comprises the step of rechecking after the second straightening;
optionally, a second cold drawing step is further included between the induction coil heating and the second straightening.
5. The preparation method of claim 1, wherein the continuous casting round billet is prepared by adopting electric furnace smelting, external refining, vacuum degassing and arc continuous casting processes, the smelting tapping temperature is not less than 1620 ℃, the vacuum holding time is not less than 15min, the soft blowing time is not less than 10min, aluminum wires are added in the smelting process, and pure calcium wires are fed after vacuum degassing and emptying.
6. The method according to claim 1, wherein the annular furnace heating comprises three processes of preheating, heating and soaking, wherein the preheating is performed at 790-830 ℃ for 50-55 min; the heating temperature is 990-1300 ℃ and the heating time is 50-60 min; the soaking temperature is 1250-1290 ℃ and the soaking time is 80-85 min.
7. The preparation method according to claim 1, wherein the thermal expansion temperature is 730-770 ℃, and the pushing speed is controlled to be 300-400 mm/min.
8. The method according to claim 4, wherein the first cold drawing is performed on a hydraulic cold drawing machine, and the wall-reducing amount of the steel pipe is not more than 2.2mm; if the second cold drawing is needed, heating the steel pipe subjected to the first cold drawing by an intermediate frequency hot-expanding coil, setting the heating temperature of the coil to 780-820 ℃, controlling the advancing speed of the steel pipe to be 180-220 mm/min slower than hot expansion, cooling the steel pipe, and saponifying again to carry out the second cold drawing, wherein the wall-reducing amount of the cold drawing is less than or equal to 1.3mm, so as to obtain the finished steel pipe.
9. The method of claim 1, wherein the first acid washing comprises washing with 15-20% sulfuric acid; the second acid washing comprises washing with sulfuric acid with the concentration of 15-20%;
preferably, the temperature for heating the induction coil is 780-820 ℃;
preferably, the thermal expansion temperature is 730 ℃ to 770 ℃.
10. A seamless steel pipe for a large-caliber thin-wall alloy high-pressure gas cylinder, the diameter-wall ratio of which is not less than 50, prepared by the preparation method of the seamless steel pipe for the large-caliber thin-wall alloy high-pressure gas cylinder, according to any one of claims 1 to 9.
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|---|---|---|---|
| CN202310767942.1A CN116765166A (en) | 2023-06-27 | 2023-06-27 | Manufacturing method of seamless steel tube for large-caliber thin-wall alloy high-pressure gas cylinder with diameter-wall ratio not less than 50 |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310767942.1A CN116765166A (en) | 2023-06-27 | 2023-06-27 | Manufacturing method of seamless steel tube for large-caliber thin-wall alloy high-pressure gas cylinder with diameter-wall ratio not less than 50 |
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| CN202310767942.1A Pending CN116765166A (en) | 2023-06-27 | 2023-06-27 | Manufacturing method of seamless steel tube for large-caliber thin-wall alloy high-pressure gas cylinder with diameter-wall ratio not less than 50 |
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