A method for manufacturing a large-diameter seamless gas cylinder tube

Abstract

The application discloses a preparation method of a large-diameter seamless gas cylinder pipe and relates to the field of seamless steel pipe manufacturing. The preparation method of the large-diameter seamless gas cylinder pipe comprises the following steps: continuous casting blank heating, plug-type piercing, precision rolling, sizing, straightening, primary cold drawing, grinding, primary flaw detection and thickness measurement, secondary cold drawing, and secondary flaw detection and thickness measurement. Through a double treatment mode of hot rolling and cold drawing, the deformation amount in the hot rolling and cold drawing steps of the gas cylinder pipe is reasonably distributed, the wall thickness precision of the large-diameter gas cylinder pipe and the quality of the inner and outer surfaces of the gas cylinder pipe are improved, and the yield of the seamless gas cylinder pipe reaches more than 85%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of seamless steel pipe manufacturing, in particular to a preparation method of large-diameter seamless gas cylinder pipe. BACKGROUND

[0002] With the enhancement of environmental awareness, the automobile industry is developing towards pollution-free direction, and the fuel of automobile is changing from gasoline to compressed natural gas, so the demand for compressed natural gas cylinder for vehicles and gas cylinder for gas station is increasing, and the demand for large-diameter gas cylinder pipe in the market is also increasing.

[0003] At present, the domestic large-diameter seamless gas cylinder pipe mainly adopts φ559 series, and φ719 series is still in the research and development blank. Among them, the φ719*21.5mm large-diameter seamless gas cylinder pipe has large diameter, large D / t, high wall thickness precision and surface quality requirement, which causes large hot working difficulty, and in the process flow, due to the wall thickness and surface control, it is easy to produce waste products, resulting in low steel pipe yield, high whole branch scrap rate and high production cost. SUMMARY

[0004] In order to improve the yield of φ719*21.5mm large-diameter seamless gas cylinder pipe and reduce the generation of waste products, the present application provides a preparation method of large-diameter seamless gas cylinder pipe.

[0005] The preparation method of large-diameter seamless gas cylinder pipe provided by the present application adopts the following technical scheme:

[0006] A preparation method of large-diameter seamless gas cylinder pipe, comprising the following steps

[0007] Continuous casting billet heating: using heating equipment to heat the solid continuous casting billet with a diameter of 700mm, and the continuous casting billet has an out-of-furnace temperature of 1240-1260℃;

[0008] Bushing piercing: using a bushing piercing machine to pierce the continuous casting billet after out of the furnace to obtain a rough pipe, and the rough pipe has an outer diameter of 738-750mm and a wall thickness of 34-40mm;

[0009] Precision rolling: when the temperature of the rough pipe is 1150-1200℃, the rough pipe is rolled to obtain a rough pipe, and the rough pipe has an outer diameter of 762-777mm and a wall thickness of 27.1-34.8mm;

[0010] Sizing: sizing the rough pipe to obtain a steel pipe; the steel pipe has an outer diameter of 727.6-750.2mm and a wall thickness of 27.1-35mm;

[0011] Straightening: straightening the steel pipe, and the straightness of the steel pipe after straightening is ≤2mm / m; the full-length bending degree is ≤20mm.

[0012] First cold drawing: the straightened steel pipe is subjected to flat head, annealing and first cold drawing; the outer diameter of the steel pipe after the first cold drawing is 719-733mm, and the wall thickness is 22-30.25mm;

[0013] Grinding: the inner and outer surfaces of the steel pipe after the internal sizing are ground, and the outer diameter of the steel pipe after the grinding is controlled to be 718-736mm, and the wall thickness is 21-29.5mm;

[0014] First flaw detection and thickness measurement: the steel pipe after the grinding is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the qualified steel pipes and unqualified steel pipes are separated; second cold drawing: the outer diameter of the steel pipe after the second cold drawing is 716-730mm, and the wall thickness is 21.5-25.5mm;

[0015] Second flaw detection and thickness measurement: the steel pipe after the cold drawing is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the unqualified products are separated, and the large-diameter seamless cylinder pipe with a diameter greater than 700mm is obtained.

[0016] The application directly prepares the large-diameter cylinder pipe with a diameter greater than 700mm by using the continuous casting blank with a diameter of 700mm, which is beneficial to reduce the production cost and shorten the process flow.

[0017] In the application, the double treatment mode of hot rolling + cold drawing is selected to solve the problems of low wall thickness precision, difficult control of surface quality, low material yield and high whole scrap rate caused by directly preparing the large-diameter cylinder pipe with a diameter greater than 700mm by using the continuous casting blank with a diameter of 700mm, the deformation amount in the hot rolling and cold drawing steps of the cylinder pipe is reasonably distributed, the wall thickness precision of the large-diameter cylinder pipe and the quality of the inner and outer surfaces of the cylinder pipe are improved, the material yield is greater than 85%, and the scrap rate is greatly reduced.

[0018] Secondly, when the blank is rolled, the temperature of the blank is controlled at 1150-1200℃, at this time, the blank still has good plasticity, the rolling force can be reduced, and the equipment can be protected.

[0019] Optionally, in the continuous casting blank heating step, the heating rate of the heating equipment is controlled at 50-60℃ / min before the temperature of the continuous casting blank reaches 700℃, the heating rate of the heating equipment is controlled at 80-100℃ / min when the temperature of the continuous casting blank is 700-1050℃, and the heating rate of the heating equipment is controlled at 10-20℃ / min when the temperature of the continuous casting blank is 1050℃<1260℃; after the temperature of the continuous casting blank reaches 1260℃, the temperature is kept for 100-150min.

[0020] When the continuous casting billet is heated, the heating rate of the heating equipment is adjusted in three steps. Among them, before the temperature of the continuous casting billet reaches 700℃, the heating rate should not be too fast, because too high heating rate is easy to cause the problem of surface delamination due to local over-temperature of the continuous casting billet; after the temperature of the continuous casting billet reaches 700℃, at this time, the heating rate needs to be accelerated to make the continuous casting billet realize plastic transformation quickly; after the temperature of the continuous casting billet reaches 1050℃, the heating rate is adjusted to 10-20℃ / min, which is beneficial to make the temperature inside and outside the continuous casting billet be in a relatively uniform state, is beneficial to improve the wall thickness precision of the gas cylinder pipe, and can also improve the strength performance of the gas cylinder pipe. After the temperature of the continuous casting billet reaches 1260℃, stop heating, which can prevent the problem of over-burning of the continuous casting billet due to over-temperature of the continuous casting billet, and affect the strength of the gas cylinder pipe due to intergranular decarburization.

[0021] Optionally, when the hollow pipe is being sized, the temperature of the hollow pipe is 800-900℃.

[0022] When the hollow pipe is being sized, the temperature of the hollow pipe is controlled at 800-900℃, which is beneficial to improve the sizing efficiency, and at the same time, will not affect the quality of the outer surface of the hollow pipe.

[0023] Optionally, when the sized steel pipe is being straightened, the temperature of the steel pipe is 250-300℃.

[0024] The straightening temperature of the steel pipe is 250-300℃, which is beneficial to prevent the straightening crack phenomenon, and is beneficial to improve the straightness of the large-diameter seamless gas cylinder pipe.

[0025] Optionally, when the straightened steel pipe is being cold-drawn for the first time, the temperature of the steel pipe is normal temperature.

[0026] When the steel pipe is being cold-drawn for the first time, the temperature of the steel pipe is controlled at normal temperature, which is beneficial to improve the efficiency of the first cold-drawing, and at the same time, will not affect the quality of the inner surface of the steel pipe.

[0027] Optionally, the cold-drawing includes the following steps:

[0028] Shot blasting treatment: using a shot blasting device to perform shot blasting treatment on the steel pipe before the second cold-drawing;

[0029] Phosphating treatment: putting the steel pipe after the shot blasting treatment into a phosphating liquid to perform phosphating treatment to form a phosphating film, and then washing it in clean water for 2-3 times to obtain a phosphated steel pipe;

[0030] Saponification treatment: putting the phosphated steel pipe into a saponification liquid to perform saponification treatment to obtain a saponified steel pipe;

[0031] Cold-drawing treatment: using a cold-drawing device to perform cold-drawing on the saponified steel pipe.

[0032] Before the steel pipe is subjected to cold drawing treatment, the steel pipe is subjected to shot blasting, phosphating and saponification treatment, which is beneficial to prevent the surface defects of the steel pipe in the cold drawing process. Among them, the steel pipe is subjected to shot blasting treatment and then subjected to phosphating treatment, which is beneficial to improve the bonding stability of the phosphating film and the steel pipe; in addition, the saponification treatment of the phosphated steel pipe can improve the cold drawing efficiency of the steel pipe.

[0033] Optionally, in the shot blasting treatment, the shot material is cast steel shot with a diameter of 1.0-1.4 mm, and the qualified steel pipe has a running speed of 3-4 m / min and a shot blasting amount of 200 kg / min.

[0034] The shot material is cast steel shot with a diameter of 1.0-1.4 mm, and the grooves generated on the surface of the steel pipe subjected to shot blasting treatment have a small diameter and size, so the surface of the steel pipe has a smooth feel and does not have obvious burr feeling.

[0035] Optionally, in the phosphating treatment, the temperature of the phosphating solution is 60-70℃, and the phosphating time is 20-30 min.

[0036] When the temperature of the phosphating solution is 60-70℃, the phosphating solution is beneficial to form a phosphating film on the inner and outer surfaces of the steel pipe to protect the surface of the steel pipe.

[0037] Optionally, in the saponification treatment, the temperature of the saponification solution is 60-70℃, and the saponification time is 5-10 min.

[0038] Controlling the temperature of the saponification solution at 60-70℃ is beneficial to improve the saponification treatment effect of the surface of the steel pipe, reduce the friction of the steel pipe entering the die hole of the cold drawing equipment, and improve the service life of the die in the cold drawing equipment.

[0039] In summary, the technical scheme of the present application has at least the following beneficial effects:

[0040] 1. The present application directly prepares large-diameter gas cylinder pipes with a diameter of 700 mm or more from continuous casting billets with a diameter of 700 mm, which is beneficial to reduce production cost and shorten process flow. Among them, in view of the problems of low wall thickness accuracy, difficult to control surface quality, low yield and high scrap rate caused by directly preparing large-diameter gas cylinder pipes with a diameter of 700 mm or more from continuous casting billets with a diameter of 700 mm, the present application selects a double treatment mode of hot rolling + twice cold drawing, and by reasonably distributing the deformation amount in each step of hot rolling and cold drawing of the gas cylinder pipe, the wall thickness accuracy of the large-diameter gas cylinder pipe and the quality of the inner and outer surfaces of the gas cylinder pipe are improved, the yield is 85% or more, and the scrap rate is greatly reduced.

[0041] 2. When heating the continuous casting billet, the heating rate of the heating equipment is adjusted in three steps. Among them, before the temperature of the continuous casting billet reaches 700℃, the heating rate should not be too fast, because too high heating rate is easy to cause the problem of surface delamination due to local high temperature of the continuous casting billet; when the temperature of the continuous casting billet reaches 700℃, at this time, the heating rate needs to be accelerated to make the continuous casting billet quickly realize plastic transformation; after the temperature of the continuous casting billet reaches 1050℃, the heating rate is adjusted to 10-20℃ / min, which is beneficial to make the temperature inside and outside the continuous casting billet in a relatively uniform state, and is beneficial to improve the wall thickness precision of the gas cylinder pipe and also can improve the strength performance of the gas cylinder pipe. After the temperature of the continuous casting billet reaches 1260℃, stop heating, which can prevent the problem of overburning of the continuous casting billet due to too high temperature of the continuous casting billet, and affect the strength of the gas cylinder pipe due to intergranular decarburization. DETAILED DESCRIPTION

[0042] The application will be further described below in combination with the examples and comparative examples of the application.

[0043] Example

[0044] Example 1

[0045] A preparation method of a large-diameter seamless gas cylinder pipe, comprising the following steps:

[0046] S1, heating the continuous casting billet: using a heating equipment to heat the 4130X solid continuous casting billet with a diameter of 700mm, the heating rate of the heating equipment is controlled at 50℃ / min, and when the temperature of the continuous casting billet reaches 1260℃, the temperature is kept for 100min. The discharge temperature of the continuous casting billet is 1240℃;

[0047] S2, piercing: using a piercing machine to pierce the continuous casting billet after discharging to obtain a rough pipe with an outer diameter of 740.2mm and a wall thickness of 34.5mm;

[0048] S3, precision rolling: when the temperature of the rough pipe decreases to 1200℃, the rough pipe is rolled to obtain a crude pipe, the diameter expansion rate of the crude pipe is controlled at 3.1%, and the wall thickness reduction rate is controlled at 10.14%;

[0049] S4, sizing: using a sizing machine to size the crude pipe with a temperature of 900℃ to obtain a steel pipe, the diameter reduction rate of the steel pipe is controlled at 3.67%, and the wall thickness reduction rate is controlled at 0%;

[0050] S5, straightening: using a straightening equipment to straighten the steel pipe with a temperature of 300℃, the straightness of the straightened steel pipe is ≤2mm / m, and the full-length bending degree is ≤20mm;

[0051] S6, first cold drawing: the straightened steel pipe with a temperature of room temperature is subjected to flat head, annealing and first cold drawing, wherein the first cold drawing comprises the following steps:

[0052] (1) shot blasting treatment: the shot blasting equipment is used to perform shot blasting treatment on the steel pipe; wherein, the shot material is cast steel shot with a diameter of 1.0 mm, the running speed of the qualified steel pipe is 4 m / min, and the shot blasting amount is 200 kg / min;

[0053] (2) phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution with a temperature of 60°C to perform phosphating for 30 min, so as to form a phosphating film on the surface of the steel pipe, and then is washed twice in clean water to obtain a phosphated steel pipe;

[0054] (3) saponification treatment: the phosphated steel pipe is placed in a saponification solution with a temperature of 70°C to perform saponification treatment for 5 min, so as to obtain a saponified steel pipe;

[0055] (4) primary cold-drawing treatment: the saponified steel pipe is subjected to primary cold-drawing by using a cold-drawing equipment, and the reduction rate of the diameter of the steel pipe after the primary cold-drawing is controlled to be 2.04%, and the wall reduction rate is controlled to be 11.29%;

[0056] S7, grinding: the inner and outer surfaces of the steel pipe after the internal sizing are ground, and the reduction rate of the diameter of the steel pipe after the grinding is 0.05%, and the wall reduction rate is controlled to be 1.69%;

[0057] S8, primary flaw detection and thickness measurement: the steel pipe after the grinding is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the qualified steel pipe and the unqualified steel pipe are separated;

[0058] S9, secondary cold-drawing:

[0059] (1) shot blasting treatment: the qualified steel pipe after the primary flaw detection and thickness measurement is subjected to shot blasting treatment by using a shot blasting equipment; wherein, the shot material is cast steel shot with a diameter of 1.0 mm, the running speed of the qualified steel pipe is 4 m / min, and the shot blasting amount is 200 kg / min;

[0060] (2) phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution with a temperature of 60°C to perform phosphating for 30 min, so as to form a phosphating film on the surface of the steel pipe, and then is washed twice in clean water to obtain a phosphated steel pipe;

[0061] (3) saponification treatment: the phosphated steel pipe is placed in a saponification solution with a temperature of 70°C to perform saponification treatment for 5 min, so as to obtain a saponified steel pipe;

[0062] (4) secondary cold-drawing treatment: the saponified steel pipe is subjected to secondary cold-drawing by using a cold-drawing equipment, and the reduction rate of the diameter of the steel pipe after the secondary cold-drawing treatment is 0.27%, and the wall reduction rate is controlled to be 15.27%;

[0063] S10, secondary flaw detection and thickness measurement: the steel pipe after the secondary cold-drawing is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the unqualified product is separated, so as to obtain a large-diameter seamless gas cylinder pipe with a diameter greater than 700 mm.

[0064] Example 2

[0065] A method for preparing a large-diameter seamless gas cylinder pipe, which differs from example 1 in that:

[0066] S1, heating of the continuous casting billet: the 4130X solid continuous casting billet with a diameter of 700 mm is heated using a heating device, the heating rate of the heating device is controlled at 50℃ / min before the temperature of the continuous casting billet reaches 700℃, the heating rate of the heating device is controlled at 100℃ / min when the temperature of the continuous casting billet is at 700-1050℃, the heating rate of the heating device is controlled at 50℃ / min when the temperature of the continuous casting billet is at 1050℃<1260℃; after the temperature of the continuous casting billet reaches 1260℃, the temperature is kept for 100 min; the discharge temperature of the continuous casting billet is 1240℃;

[0067] S2, bacterial perforation: the discharged continuous casting billet is perforated using a bacterial perforator to obtain a rough pipe with an outer diameter of 740.9 mm and a wall thickness of 35 mm.

[0068] Example 3

[0069] A method for preparing a large-diameter seamless gas cylinder pipe, which differs from example 2 in that:

[0070] In the S1 step, the heating rate of the heating device is controlled at 20℃ / min when the temperature of the continuous casting billet is at 1050℃<1260℃;

[0071] In the S2 step, a rough pipe with an outer diameter of 739.4 mm and a wall thickness of 34 mm is obtained.

[0072] Example 4

[0073] A method for preparing a large-diameter seamless gas cylinder pipe, which differs from example 2 in that the control parameters of each step are different, specifically as follows:

[0074] S1, heating of the continuous casting billet: the 4130X solid continuous casting billet with a diameter of 700 mm is heated using a heating device, the heating rate of the heating device is controlled at 60℃ / min before the temperature of the continuous casting billet reaches 700℃, the heating rate of the heating device is controlled at 80℃ / min when the temperature of the continuous casting billet is at 700-1050℃, the heating rate of the heating device is controlled at 10℃ / min when the temperature of the continuous casting billet is at 1050℃<1260℃; after the temperature of the continuous casting billet reaches 1260℃, the temperature is stopped and kept for 150 min. The discharge temperature of the continuous casting billet is 1260℃;

[0075] S2, bacterial perforation: the discharged continuous casting billet is perforated using a bacterial perforator to obtain a rough pipe with an outer diameter of 745.3 mm and a wall thickness of 36 mm;

[0076] S3, precision rolling: when the temperature of the hollow tube is reduced to 1150°C, the hollow tube is rolled to obtain a rough pipe, the diameter expansion rate of the rough pipe is controlled at 3.2%, and the wall reduction rate is controlled at 10.2%;

[0077] S4, sizing: the rough pipe with a temperature of 800°C is sized by a sizing machine to obtain a steel pipe, the diameter reduction rate of the steel pipe is controlled at 3.55%, and the wall reduction rate is controlled at 15.56%;

[0078] S5, straightening: the steel pipe with a temperature of 250°C is straightened by a straightening device, the straightness of the straightened steel pipe is ≤2mm / m, and the full-length bending degree is ≤20mm;

[0079] S6, primary cold drawing: the steel pipe after straightening with a normal temperature is subjected to a flat head, annealing and primary cold drawing, wherein the primary cold drawing comprises the following steps:

[0080] (1) shot blasting treatment: the steel pipe is subjected to shot blasting treatment by a shot blasting device; wherein the shot material is cast steel shot with a diameter of 1.0mm, the running speed of the qualified steel pipe is 4m / min, and the shot blasting amount is 200kg / min;

[0081] (2) phosphating treatment: the steel pipe after shot blasting treatment is put into a phosphating solution with a temperature of 60°C for phosphating for 30min to form a phosphating film on the surface of the steel pipe, and then is washed twice in clean water to obtain a phosphated steel pipe;

[0082] (3) saponification treatment: the phosphated steel pipe is placed in a saponification solution with a temperature of 70°C for saponification treatment for 5min to obtain a saponified steel pipe;

[0083] (4) primary cold drawing treatment: the saponified steel pipe is subjected to primary cold drawing by a cold drawing device, the diameter reduction rate of the steel pipe after primary cold drawing is controlled at 2.1%, and the wall reduction rate is controlled at 11.5%;

[0084] S7, grinding: the inner and outer surfaces of the steel pipe after inner sizing are ground, the diameter reduction rate of the ground steel pipe is 0.06%, and the wall reduction rate is controlled at 1.72%;

[0085] S8, primary flaw detection and thickness measurement: the steel pipe after grinding is subjected to flaw detection and thickness measurement by ultrasonic waves, and the qualified steel pipe and the unqualified steel pipe are separated;

[0086] S9, secondary cold drawing:

[0087] (1) shot blasting treatment: the qualified steel pipe after primary flaw detection and thickness measurement is subjected to shot blasting treatment by a shot blasting device; wherein the shot material is cast steel shot with a diameter of 1.4mm, the running speed of the qualified steel pipe is 3m / min, and the shot blasting amount is 200kg / min;

[0088] (2) Phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution at a temperature of 70°C for phosphating for 20 min to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 3 times to obtain a phosphated steel pipe;

[0089] (3) Saponification treatment: the phosphated steel pipe is placed in a saponification solution at a temperature of 60°C for saponification treatment for 10 min to obtain a saponified steel pipe;

[0090] (4) Secondary cold-drawing treatment: the saponified steel pipe is subjected to secondary cold-drawing treatment by using a cold-drawing device, and the reduction ratio of the diameter of the steel pipe after the secondary cold-drawing treatment is 0.35%, and the wall thickness reduction ratio is controlled to be 15.11%;

[0091] S10, Secondary flaw detection and thickness measurement: the steel pipe after the secondary cold-drawing treatment is subjected to flaw detection and thickness measurement by using ultrasonic waves, and unqualified products are separated to obtain a large-diameter seamless gas cylinder pipe with a diameter greater than 700 mm.

[0092] Example 5

[0093] A preparation method of a large-diameter seamless gas cylinder pipe, which is different from that of Example 2 in that the control parameters of each step are different, and specifically as follows:

[0094] S1, Continuous casting blank heating: a 4130X solid continuous casting blank with a diameter of 700 mm is heated by using a heating device, the heating rate of the heating device is controlled to be 60°C / min before the temperature of the continuous casting blank reaches 700°C, the heating rate of the heating device is controlled to be 80°C / min when the temperature of the continuous casting blank is 700-1050°C, the heating rate of the heating device is controlled to be 10°C / min when the temperature of the continuous casting blank is 1050°C<1260°C; after the temperature of the continuous casting blank reaches 1260°C, the heating is stopped, and the temperature is kept for 150 min. The discharge temperature of the continuous casting blank is 1260°C;

[0095] S2, Mandrel piercing: the continuous casting blank after being discharged is subjected to piercing by using a mandrel piercing machine to obtain a rough pipe with an outer diameter of 750 mm and a wall thickness of 40 mm;

[0096] S3, Precision rolling: when the temperature of the rough pipe decreases to 1200°C, the rough pipe is subjected to rolling to obtain a crude pipe, and the expansion ratio of the crude pipe is controlled to be 3.5%, and the wall thickness reduction ratio is controlled to be 22.5%;

[0097] S4, Sizing: the crude pipe at a temperature of 900°C is subjected to external sizing by using a sizing machine to obtain a steel pipe, and the reduction ratio of the diameter of the steel pipe is controlled to be 3.45%, and the wall thickness reduction ratio is controlled to be 16.52%;

[0098] S5, Straightening: the steel pipe at a temperature of 450°C is subjected to straightening by using a straightening device, and the straightness of the steel pipe after the straightening is ≤2 mm / m, and the full-length bending degree is ≤20 mm;

[0099] S6, once cold drawing: the steel pipe with normal temperature after straightening is carried out flat head, annealing and once cold drawing, wherein, the once cold drawing comprises the following steps:

[0100] (1) shot blasting treatment: the steel pipe is subjected to shot blasting treatment by using a shot blasting device; wherein, the shot material is cast steel shot with a diameter of 1.0 mm, the running speed of the qualified steel pipe is 4 m / min, and the shot blasting amount is 200 kg / min;

[0101] (2) phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution with a temperature of 60℃ for phosphating for 30 min, so as to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 2 times to obtain a phosphating steel pipe;

[0102] (3) saponification treatment: the phosphating steel pipe is placed in a saponification solution with a temperature of 70℃ for saponification treatment for 5 min to obtain a saponification steel pipe;

[0103] (4) once cold drawing treatment: the saponification steel pipe is subjected to once cold drawing by using a cold drawing device, and the reduction rate of the steel pipe after the once cold drawing is controlled to be 2.3%, and the wall reduction rate is controlled to be 12.65%;

[0104] S7, grinding: the inner and outer surfaces of the steel pipe after the internal sizing are ground, and the reduction rate of the steel pipe after the grinding is 0.08%, and the wall reduction rate is controlled to be 2.68%;

[0105] S8, once flaw detection and thickness measurement: the steel pipe after the grinding is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the qualified steel pipe and the unqualified steel pipe are separated;

[0106] S9, secondary cold drawing:

[0107] (1) shot blasting treatment: the qualified steel pipe after the once flaw detection and thickness measurement is subjected to shot blasting treatment by using a shot blasting device; wherein, the shot material is cast steel shot with a diameter of 1.4 mm, the running speed of the qualified steel pipe is 3 m / min, and the shot blasting amount is 200 kg / min;

[0108] (2) phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution with a temperature of 70℃ for phosphating for 20 min, so as to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 3 times to obtain a phosphating steel pipe;

[0109] (3) saponification treatment: the phosphating steel pipe is placed in a saponification solution with a temperature of 60℃ for saponification treatment for 10 min to obtain a saponification steel pipe;

[0110] (4) cold drawing treatment: the saponification steel pipe is subjected to cold drawing by using a cold drawing device, and the reduction rate of the steel pipe after the cold drawing treatment is 0.25%, and the wall reduction rate is controlled to be 14.65%;

[0111] S10, secondary flaw detection and thickness measurement: ultrasonic flaw detection and thickness measurement are performed on the steel pipe after secondary cold drawing, unqualified products are separated, and large-diameter seamless gas cylinder pipe with a diameter greater than 700 mm is obtained.

[0112] Comparative example

[0113] Comparative example 1

[0114] A preparation method of a large-diameter seamless gas cylinder pipe, comprising the following steps:

[0115] S1, continuous casting billet heating: a 4130X solid continuous casting billet with a diameter of 700 mm is heated using a heating device, the heating rate of the heating device is controlled at 50 ℃ / min, and when the temperature of the continuous casting billet reaches 1260 ℃, the temperature is maintained for 100 min. The discharge temperature of the continuous casting billet is 1240 ℃;

[0116] S2, mandrel piercing: the continuous casting billet after discharge is pierced using a mandrel piercing machine to obtain a rough pipe with an outer diameter of 741.6 mm and a wall thickness of 33.5 mm;

[0117] S3, precision rolling: when the temperature of the rough pipe decreases to 1250 ℃, the rough pipe is rolled to obtain a rough pipe, and the diameter expansion rate of the rough pipe is controlled at 3.6%, and the wall thickness reduction rate is controlled at 11.05%;

[0118] S4, sizing: the rough pipe with a temperature of 1000 ℃ is sized using a sizing machine to obtain a steel pipe, and the diameter reduction rate of the steel pipe is controlled at 3.05%, and the wall thickness reduction rate is controlled at 0%;

[0119] S5, straightening: the steel pipe with a temperature of 300 ℃ is straightened using a straightening device, and the straightness of the steel pipe after straightening is ≤2 mm / m, and the full-length bending degree is ≤20 mm;

[0120] S6, primary cold drawing: the steel pipe after straightening with a temperature of room temperature is subjected to flat head, annealing and primary cold drawing, wherein the primary cold drawing comprises the following steps:

[0121] (1) shot blasting treatment: shot blasting equipment is used for shot blasting treatment of the steel pipe; wherein the shot material is cast steel shot with a diameter of 1.0 mm, the running speed of the qualified steel pipe is 4 m / min, and the shot blasting amount is 200 kg / min;

[0122] (2) phosphating treatment: the steel pipe after shot blasting treatment is put into a phosphating solution with a temperature of 60 ℃ for phosphating for 30 min to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 2 times to obtain a phosphated steel pipe;

[0123] (3) saponification treatment: the phosphated steel pipe is placed in a saponification solution with a temperature of 70 ℃ for saponification treatment for 5 min to obtain a saponified steel pipe;

[0124] (4) once cold-drawing treatment: using a cold-drawing device to cold-draw the saponified steel pipe, the diameter reduction rate of the steel pipe after once cold-drawing is controlled to be 2.06%, and the wall thickness reduction rate is controlled to be 11.23%;

[0125] S7, grinding: grinding the inner and outer surfaces of the steel pipe after internal sizing, the diameter reduction rate of the steel pipe after grinding is 0.05%, and the wall thickness reduction rate is controlled to be 2.73%;

[0126] S8, once flaw detection and thickness measurement: using ultrasonic waves to detect flaws and measure the thickness of the steel pipe after grinding, separating out unqualified products, and obtaining large-diameter seamless cylinder pipes with a diameter greater than 700mm.

[0127] Comparative Example 2

[0128] A preparation method of a large-diameter seamless cylinder pipe, comprising the following steps:

[0129] S1, continuous casting blank heating: using a heating device to heat a 4130X solid continuous casting blank with a diameter of 700mm, the heating rate of the heating device is controlled to be 50℃ / min, and when the temperature of the continuous casting blank reaches 1260℃, the temperature is maintained for 100min. The discharge temperature of the continuous casting blank is 1240℃;

[0130] S2, button piercing: using a button piercing machine to pierce the continuous casting blank after discharging, to obtain a rough pipe with an outer diameter of 749.9mm and a wall thickness of 36.5mm;

[0131] S3, precision rolling: when the temperature of the rough pipe decreases to 1200℃, the rough pipe is rolled to obtain a rough pipe, the diameter expansion rate of the rough pipe is controlled to be 2.32%, and the wall thickness reduction rate is controlled to be 11.54%;

[0132] S4, sizing: using a sizing machine to externally size the rough pipe with a temperature of 900℃ to obtain a steel pipe, the diameter reduction rate of the steel pipe is controlled to be 4.35%, and the wall thickness reduction rate is controlled to be 0%;

[0133] S5, straightening: using a straightening device to straighten the steel pipe with a temperature of 300℃, the straightness of the steel pipe after straightening is ≤2mm / m, and the full-length bending degree is ≤20mm;

[0134] S6, once cold-drawing: the steel pipe with a temperature of room temperature after straightening is subjected to flat head, annealing and once cold-drawing, wherein the once cold-drawing comprises the following steps:

[0135] (1) shot blasting treatment: using a shot blasting device to perform shot blasting treatment on the steel pipe; wherein the shot material is cast steel shot with a diameter of 1.0mm, the running speed of the qualified steel pipe is 4m / min, and the shot blasting amount is 200kg / min;

[0136] (2) Phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution at a temperature of 60°C for phosphating for 30 min to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 2 times to obtain a phosphated steel pipe;

[0137] (3) Saponification treatment: the phosphated steel pipe is placed in a saponification solution at a temperature of 70°C for saponification treatment for 5 min to obtain a saponified steel pipe;

[0138] (4) First cold drawing treatment: the saponified steel pipe is subjected to a first cold drawing by using a cold drawing equipment, and the reduction ratio of the diameter of the steel pipe after the first cold drawing is controlled to be 2.12%, and the wall reduction ratio is controlled to be 11.63%;

[0139] S7, grinding: the inner and outer surfaces of the steel pipe after the internal sizing are ground, and the reduction ratio of the diameter of the steel pipe after the grinding is 0.07%, and the wall reduction ratio is controlled to be 2.27%;

[0140] S8, second flaw detection and thickness measurement: the steel pipe after the grinding is subjected to flaw detection and thickness measurement by using ultrasonic waves, and the qualified steel pipes and unqualified steel pipes are separated;

[0141] S9, cold drawing:

[0142] (1) Shot blasting treatment: the qualified steel pipe after the second flaw detection and thickness measurement is subjected to shot blasting treatment by using a shot blasting equipment; wherein, the shot material is cast steel shot with a diameter of 1.0 mm, the running speed of the qualified steel pipe is 4 m / min, and the shot blasting amount is 200 kg / min;

[0143] (2) Phosphating treatment: the steel pipe after the shot blasting treatment is put into a phosphating solution at a temperature of 60°C for phosphating for 30 min to form a phosphating film on the surface of the steel pipe, and then is washed in clean water for 2 times to obtain a phosphated steel pipe;

[0144] (3) Saponification treatment: the phosphated steel pipe is placed in a saponification solution at a temperature of 70°C for saponification treatment for 5 min to obtain a saponified steel pipe;

[0145] (4) Cold drawing treatment: the saponified steel pipe is subjected to cold drawing by using a cold drawing equipment, and the reduction ratio of the diameter of the steel pipe after the cold drawing treatment is 0.57%, and the wall reduction ratio is controlled to be 11.85%;

[0146] S10, second flaw detection and thickness measurement: the steel pipe after the cold drawing is subjected to flaw detection and thickness measurement by using ultrasonic waves, and unqualified products are separated to obtain large-diameter seamless cylinder pipes with a diameter greater than 700 mm.

[0147] Performance detection data

[0148] 1. Yield: b = Q / G x 100; wherein, b is the yield, %, Q is the weight of qualified products, unit ton, and G is the weight of input raw materials, unit ton.

[0149] 2. Wall thickness unevenness: tested according to GB / T 18248-2008 "Seamless Steel Tubes for Gas Cylinders".

[0150] 3. Yield strength: longitudinal, test temperature 25℃.

[0151] 4. Tensile strength: longitudinal, test temperature 25℃.

[0152] Table 1 Performance of large-diameter seamless gas cylinder tube

[0153]

[0154]

[0155] Comparative Example 1 and Comparative Example 1, wherein, compared with Example 1, the seamless gas cylinder tube in Comparative Example 1 only undergoes one cold drawing. It can be seen from the data in Table 1 that when the large-diameter seamless gas cylinder tube with a diameter of more than 700 mm is prepared by one cold drawing, the yield of the seamless gas cylinder tube decreases, the wall thickness unevenness increases, and the mechanical properties decrease. Therefore, it can be seen that when the large-diameter seamless gas cylinder tube with a diameter of more than 700 mm is prepared by one cold drawing, the scrap rate of the seamless gas cylinder tube is increased, the production cost is increased, and at the same time, it is not conducive to the improvement of the wall thickness precision and the mechanical properties of the seamless gas cylinder tube.

[0156] Comparative Example 1 and Comparative Example 2, wherein, compared with Example 1, the distribution of deformation of the seamless gas cylinder tube in Comparative Example 2 is not within the scope of the present application. It can be seen from the data in Table 1 that the distribution of deformation of the seamless gas cylinder tube will affect the yield, wall thickness precision and mechanical properties of the large-diameter seamless gas cylinder tube with a diameter of more than 700 mm.

[0157] Comparative Example 1-3, the difference between Example 1-3 is that the heating rate of the heating equipment is different in the continuous casting billet heating step. Among them, the heating rate of the heating equipment in Example 1 remains unchanged, the heating rate of the heating equipment in Example 2 is adjusted in three steps, and although the heating rate of the heating equipment in Example 3 is also adjusted in three steps, the control of the heating rate in the third step in Example 3 is different from that in Example 2. It can be seen from the data in Table 1 that compared with Example 2, the wall thickness unevenness of the seamless gas cylinder tube in Example 1 and Example 3 increases, and the yield strength and tensile strength decrease. Therefore, it can be seen that the heating rate affects the performance of the large-diameter seamless gas cylinder tube with a diameter of more than 700 mm.

[0158] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method of manufacturing a large diameter seamless gas cylinder tube, characterized by, The method comprises the following steps: Continuous casting billet heating: a heating device is used to heat a solid continuous casting billet with a diameter of 700 mm, and the billet has an out-of-furnace temperature of 1240-1260 ℃; before the temperature of the continuous casting billet reaches 700 ℃, the heating device is controlled to have a temperature rising rate of 50-60 ℃ / min, when the temperature of the continuous casting billet is 700-1050 ℃, the heating device is controlled to have a temperature rising rate of 80-100 ℃ / min, and when the temperature of the continuous casting billet is 1050 ℃<1260 ℃, the heating device is controlled to have a temperature rising rate of 10-20 ℃ / min; after the temperature of the continuous casting billet reaches 1260 ℃, the temperature is maintained for 100-150 min; Bacterial piercing: a bacterial piercing machine is used to pierce the continuous casting billet after it is discharged from the furnace to obtain a rough pipe, and the rough pipe has an outer diameter of 738-750 mm and a wall thickness of 34-40 mm; Precision rolling: when the temperature of the rough pipe reaches 1150-1200 ℃, the rough pipe is rolled to obtain a crude pipe, and the crude pipe has an outer diameter of 762-777 mm and a wall thickness of 27.1-34.8 mm; Sizing: the crude pipe is sized to obtain a steel pipe, and the steel pipe has an outer diameter of 727.6-750.2 mm and a wall thickness of 27.1-35 mm; when the crude pipe is sized, the temperature of the crude pipe is 800-900 ℃; Straightening: the steel pipe is straightened, and the straightness of the steel pipe after straightening is ≤2 mm / m; the full-length bending degree is ≤20 mm; when the sized steel pipe is straightened, the temperature of the steel pipe is 250-300 ℃; Primary cold drawing: the straightened steel pipe is subjected to flat head, annealing and primary cold drawing; the outer diameter of the steel pipe after primary cold drawing is 719-733 mm, and the wall thickness is 22-30.25 mm; when the straightened steel pipe is subjected to primary cold drawing, the temperature of the steel pipe is room temperature; Grinding: the inner and outer surfaces of the steel pipe after primary cold drawing are ground, and the outer diameter of the steel pipe after grinding is controlled to be 718-736 mm, and the wall thickness is 21-29.5 mm; Primary flaw detection and thickness measurement: ultrasonic waves are used to detect flaws and measure the thickness of the steel pipe after grinding, and the qualified steel pipes and unqualified steel pipes are separated; Secondary cold drawing: the outer diameter of the steel pipe after secondary cold drawing is 716-730 mm, and the wall thickness is 21.5-25.5 mm; Secondary flaw detection and thickness measurement: ultrasonic waves are used to detect flaws and measure the thickness of the steel pipe after secondary cold drawing, and unqualified products are separated to obtain large-diameter seamless cylinder pipes with a diameter greater than 700 mm.

2. The method of claim 1, wherein the large diameter seamless gas cylinder tube is prepared by the steps of: The primary cold drawing and the secondary cold drawing comprise the following steps: Shot blasting: a shot blasting device is used to perform shot blasting on the steel pipe before the two cold drawings; Phosphating treatment: the steel pipe after shot blasting is put into a phosphating solution for phosphating treatment to form a phosphating film, and then is washed in clean water for 2-3 times to obtain a phosphated steel pipe; Saponification treatment: the phosphated steel pipe is placed in a saponification solution for saponification treatment to obtain a saponified steel pipe; Cold drawing: a cold drawing device is used to perform cold drawing on the saponified steel pipe.

3. The method of claim 2, wherein the method further comprises the step of: During the shot blasting, cast steel shots with a diameter of 1.0-1.4 mm are selected, the qualified steel pipe has a running speed of 3-4 m / min, and the shot blasting amount is 200 kg / min.

4. The method of claim 2, wherein the method further comprises the step of: In the phosphating process, the temperature of the phosphating solution is 60-70℃, and the phosphating time is 20-30min.

5. The method for preparing a large-diameter seamless gas cylinder tube according to claim 2, characterized in that, In the saponification process, the temperature of the saponification solution is 60-70℃, and the saponification time is 5-10min.

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