CN110904384A - Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion and manufacturing process thereof - Google Patents
Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion and manufacturing process thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/18—Submerged-arc welding
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K2101/00—Articles made by soldering, welding or cutting
- B23K2101/04—Tubular or hollow articles
- B23K2101/06—Tubes
Abstract
The invention relates to the technical field of steel pipe manufacturing, and particularly discloses a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion and a manufacturing process thereof. The welded pipe comprises the following chemical components in percentage by mass: c is less than or equal to 0.10 percent, Mn: 0.70 percent～1.20％，Si≤0.45％，P≤0.020％，S≤0.008％，Cu：0.20％～0.40％，Cr：0.60％～1.00％，Sb：0.05～0.10％，Ni≤0.25％，Sn≤0.015％，B≤0.0005％，Ti：0.01～0.05％，CEpcmLess than or equal to 0.20 percent, and the balance of iron and inevitable impurities. In the manufacturing method, the strip steel is made into a spiral cylinder according to a forming angle of 79 degrees 12'. The Q345NS spiral submerged arc welded pipe provided by the invention has excellent mechanical property and sulfuric acid dew point corrosion resistance.
Description
Technical Field
The invention relates to the technical field of steel pipe manufacturing, in particular to a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion and a manufacturing process thereof.
Background
In the industrial fields of metallurgy, electric power, petrochemical industry and the like, heavy oil or coal usually contains 2 to 3 percent of sulfur, and flue gas generated after the sulfur is combusted contains about 0.2 percent of SO2，SO2SO generation under catalysis of ash and metal oxide3，SO3Then combines with the moisture contained in the combustion gas or the moisture contained in the air to generate sulfuric acid, and the sulfuric acid is at the dew point temperature (when the SO in the flue gas is3Is 30X 10-6When the dew point is about 130 to 150 ℃ or lower, dew drops are condensed and formed at low-temperature parts of equipment such as an air preheater, an economizer, a flue, a chimney and a desulfurization device of a boiler, such as a fuel oil or coal-fired boiler, and corrode metals, namely, so-called sulfuric acid dew point corrosion. The corrosion has chemical corrosion and electrochemical corrosion, the corrosion reaction type is complex, the corrosive liquid has extremely strong corrosivity, and the harm is extremely large.
At present, blast furnace gas pipelines of various large iron and steel enterprises have sulfuric acid dew point corrosion of different degrees, and the conveying safety and the service life of a gas pipe network are seriously influenced. The conveying pressure of blast furnace gas pipeline is about 12Kpa, it belongs to low-pressure large-flow conveying pipeline, its diameter range is 1000mm-3200mm, and most of said pipelines adopt three-roller forming short-section welding forming mode, and have the defects of large field construction operation quantity, long construction period, high cost, many welding seams and large appearance size difference. Therefore, the developed sulfuric acid dew point corrosion resistant Q345NS ultra-large-diameter spiral submerged arc welding pipe not only can be widely applied to the coal gas pipeline modification project of steel enterprises, but also can be used in the aspects of sulfuric acid dew point corrosion resistance of flue gas recovery pipelines, flues and the like in the industries of chemical industry, electric power, tobacco and the like, and has wide market application prospect. However, in the prior art, the Q345NS spiral welded pipe has poor sulfuric acid corrosion resistance and poor forming stability of a large-diameter steel pipe, and the popularization and the use of the Q345NS spiral submerged arc welded pipe with the ultra-large diameter are greatly limited.
Disclosure of Invention
Aiming at the problems of poor sulfuric acid corrosion resistance of a Q345NS spiral welded pipe, poor forming stability of a large-diameter steel pipe and the like in the prior art, the invention provides a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion.
And a method for manufacturing the Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion.
In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:
a sulfuric acid dew point corrosion resistant Q345NS spiral submerged arc welded pipe comprises the following chemical components in percentage by mass: c is less than or equal to 0.10 percent, Mn: 0.70-1.20%, Si is less than or equal to 0.45%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, Cu: 0.20-0.40%, Cr: 0.60% -1.00%, Sb: 0.05-0.10%, Ni is less than or equal to 0.25%, Sn is less than or equal to 0.015%, B is less than or equal to 0.0005%, Ti: 0.01 to 0.05%, CEpcmLess than or equal to 0.20 percent, and the balance of iron and inevitable impurities.
Compared with the prior art, the Q345NS spiral submerged arc welding pipe for resisting sulfuric acid dew point corrosion has the following advantages:
the invention adopts low C and low S design, adds alloy elements such as Cr, Cu, Sb and the like, considers the characteristics of the alloy elements and the interaction among the alloy elements, adds the alloy elements in a reasonable proportion and ensures the uniform distribution of the alloy elements in the coil. Cu is easily bonded to S in steel to form Cu on the surface of steel2An S passivation film, whereby electrochemical reaction of the anode and the cathode can be suppressed; cr can form a compact oxide film on the surface of steel, so that the passivation capability of the steel is improved; the Cu, Cr and Sb with specific contents are matched with each other, so that the electrochemical corrosion of the steel surface can be prevented, and the chemical corrosion of the steel surface can be inhibited, so that the Q345NS spiral submerged arc welding pipe has excellent sulfuric acid dew point corrosion resistance.
Furthermore, the invention also provides a manufacturing method of the sulfuric acid dew point corrosion resistant Q345NS spiral submerged arc welded pipe. The manufacturing method comprises an edge milling process, a forming process and a welding process, wherein the forming process forms the strip steel into a spiral cylinder according to a forming angle of 79 degrees 12'.
Compared with the prior art, the manufacturing method provided by the invention has the following advantages:
the invention ensures that all properties of the final steel pipe completely meet all requirements of the Q345NS spiral submerged arc welded pipe for resisting dew point corrosion by strict technical control of all procedures.
The forming angle of 79 degrees 12' is adopted, so that the problem that the residual circumferential stress in the tube blank is relatively small or even insufficient, and the tube collapse caused by the influence of self weight on the tube shape is difficult to offset is solved, the generation of large fluctuation range of the tube diameter and the ovality and the generation of misalignment and slotting in the forming process are avoided, and the forming stability of the spiral tube is ensured.
Preferably, the three-roll forming is adopted in the forming step, the three-roll forming includes an inner forming roll and an outer forming roll, the angle of the inner forming roll is 79 ° 10 ', the angle of the outer forming roll is 79 ° 15', the outer forming roll includes a 1# roll and a 3# roll, the wrap angle of the 1# roll is 13 ° 24 ', the open position is 149.3mm, and the wrap angle of the 3# roll is 17 ° 16', and the open position is 248.4 mm. And adjusting the 2# roller reduction according to the actual yield strength level of the rolled plate.
The strip steel is subjected to bending deformation by three groups of forming rollers, wherein the wrap angle and the opening size of the No. 1 roller, the No. 3 roller and the rolling reduction of the No. 2 roller influence the forming stability of the strip steel, and if the relevant parameters of the No. 1 roller, the No. 2 roller and the No. 3 roller are not properly set, the forming instability phenomena of large pipe diameter change, more misalignment, more slits and the like can occur.
According to the width, the thickness and the strength of the steel plate and the stability of the spiral pipe, the angles and the opening distances of the internal forming, the external forming, the wrap angle of the No. 1 roller and the wrap angle of the No. 3 roller are optimized, and the problems of large fluctuation range of the pipe diameter and the ovality and unstable pipe shape in the forming process of the low-steel-grade and large-caliber ultrathin-wall spiral submerged arc welded steel pipe are solved.
Preferably, the edge milling process adopts a double edge milling process: firstly roughly milling an I-shaped groove, and then finely milling an X-shaped groove, wherein the angle of the upper groove is 35-40 degrees, the angle of the lower groove is 40-45 degrees, and the truncated edge is 7.0-9.0 mm.
According to the invention, by optimizing the edge milling process, the groove shape favorable for forming occlusion can be obtained, the coil can be ensured to be completely welded in the welding process, the welding speed is improved, the appearance of the welding line is improved, the energy of the welding line is reduced, the influence of the welding residual stress and the welding heat input on the structure and the performance of a welding heat affected zone is reduced, the performance of the welding heat affected zone is improved, and a powerful basis is provided for the forming stability of the spiral welded pipe.
Preferably, the submerged arc welding wire adopted in the welding process comprises the following chemical components in percentage by mass: c is less than or equal to 0.12 percent, Mn: 1.0-1.60%, Si is less than or equal to 0.35%, P is less than or equal to 0.025%, S is less than or equal to 0.020%, Cu: 0.20-0.50%, Cr: 0.30% -0.90%, Ni: 0.20 to 0.80 percent, and the balance of Fe.
Preferably, the deposited metal of the welding flux adopted in the welding process comprises the following chemical components in percentage by mass: less than or equal to 0.15 percent of C, less than or equal to 1.50 percent of Mn, less than or equal to 0.35 percent of Si, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, Cu: 0.20-0.50%, Cr: 0.30% -1.20%, Ni: 0.20 to 0.80 percent, and the balance of Fe.
In the welding process, firstly, a special submerged-arc welding wire and a welding flux are selected to ensure that the chemical components of a welding seam are similar to those of a base metal, the P, S content in the welding seam is low, and the sulfuric acid dew point corrosion resistance, the good strength and the good toughness of a welding joint can be effectively ensured.
Preferably, the welding procedure comprises an inner welding procedure and an outer welding procedure, wherein the inner welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, the current is 590A-710A, and the voltage is 29V-33V; the second wire is in AC positive connection, the current is 360A-440A, and the voltage is 34V-38V; the welding speed is 0.8-1.0 m/min.
Preferably, the external welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, the current is 680A-820A, and the voltage is 30V-34V; the second wire is in AC positive connection, the current is 360A-440A, and the voltage is 34V-38V; the welding speed is 0.8-1.0 m/min.
When the welding parameters are determined, the action of each wire in the double-wire welding is fully considered, the proper penetration depth and good appearance of a welding seam are obtained by reasonably setting the current, voltage, angle, welding wire interval and welding speed of each wire, and meanwhile, the performance of a welding heat affected zone is ensured by adopting lower welding line energy. The weld joint finally obtains a structure which is mainly composed of acicular ferrite and pro-eutectoid ferrite and has good obdurability, and simultaneously, a welding heat affected zone obtains a fine granular bainite and a structure which is mainly composed of ferrite, thereby solving the obdurability problem of the welding joint of the steel pipe.
The method for manufacturing the spiral submerged arc welded pipe is particularly suitable for manufacturing large-diameter and thin-wall thick welded pipes, such as blast furnace gas pipelines with the diameter of 3020mm and the wall thickness of 12 mm.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a microstructure of the wall thickness surface of a Q345NS rolling plate provided by the embodiment 1 of the invention;
FIG. 2 is a microstructure of the center of the wall thickness of a Q345NS coil provided in example 1 of the present invention;
FIG. 3 is a sample of a uniform corrosion fully-dipped Q345NS steel grade coil provided in example 1 of the present invention;
FIG. 4 is a homogeneous corrosion fully leached coupon of Q235B steel;
FIG. 5 is a metallographic structure of a weld of a spiral steel pipe Q345NS provided in example 1 of the present invention;
FIG. 6 is a metallographic structure of a heat affected zone of a Q345NS spiral steel tube provided in example 1 of the present invention;
FIG. 7 is a ductile-brittle transition curve of a Q345NS spiral steel pipe body provided in example 1 of the present invention;
FIG. 8 is the ductile-brittle transition curve of the weld of the Q345NS spiral steel pipe provided in example 1 of the present invention;
FIG. 9 is a ductile-brittle transition curve of the hot zone of a Q345NS spiral steel pipe provided in example 1 of the present invention;
FIG. 10 is a sample of a uniform corrosion fully-dipped tube of a spiral steel tube Q345NS provided in example 1 of the present invention;
FIG. 11 is a sample of a homogeneous corrosion full dip of the weld of a Q345NS spiral steel pipe provided in example 1 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The embodiment of the invention provides a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion, wherein a used coil comprises the following components in percentage by mass: c: 0.07%, Mn: 0.79%, Si: 0.32%, P: 0.017%, S: 0.004%, Cu: 0.29%, Cr: 0.87%, Sb: 0.08%, Ni: 0.16%, Sn: 0.008%, B: 0.0003%, Ti: 0.02%, CEpcm: 0.18% and the balance iron and inevitable impurities.
The coil plate is smelted by a converter and refined outside the furnace, a light reduction is adopted in the continuous casting process, and the coil plate is rolled by matching with a reasonable rolling and cooling control process, the specification is 12 multiplied by 1800mm, and a Q345NS spiral submerged arc welded pipe with the outer diameter of 3020mm of a steel pipe is prepared.
The butt welding process comprises the steps of enabling current to be 650A, enabling voltage to be 36V and enabling the diameter of a welding wire to be 4.0 mm; the welding wire is CHW-STH500 III; flux designation CHF101 NQ; the welding speed is 0.36 mm/min.
The edge milling process adopts a double edge milling process: firstly roughly milling an I-shaped groove, removing the defects of the rolled plate and crescent to control the plate width at 1785mm, and then finely milling an X-shaped groove, wherein the angle of the upper groove is 35 degrees, the angle of the lower groove is 40 degrees, and the truncated edge is 8.0 mm.
The molding process comprises the following steps: the forming process adopts three-roller forming, the three-roller forming comprises an inner forming roller and an outer forming roller, the angle of the inner forming roller is 79 degrees 10 ', the angle of the outer forming roller is 79 degrees 15', the outer forming roller comprises a 1# roller and a 3# roller, the wrap angle of the 1# roller is 13 degrees 24 ', the opening gear is 149.3mm, the wrap angle of the 3# roller is 17 degrees 16', the opening gear is 248.4mm, and the 2# roller reduction is adjusted according to the actual yield strength level of the rolled plate.
The welding procedure comprises an inner welding procedure and an outer welding procedure, double-wire serial submerged arc automatic welding is adopted, the welding wire is CHW-STH500 III, and the welding wire comprises the following chemical components: c: 0.083%, Mn: 1.32%, Si: 0.181%, P: 0.012%, S: 0.004%, Cu: 0.238%, Cr: 0.61%, Ni: 0.36 percent; the flux is CHF101NQ, and deposited metal comprises the following chemical components: c: 0.070%, Mn: 1.45%, Si: 0.32%, P: 0.021%, S: 0.009%, Cu: 0.214%, Cr: 0.55%, Ni: 0.541 percent. The internal welding process adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, a welding wire with the diameter of 4.0mm is adopted, the current is 620A, and the voltage is 32V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 420A, and the voltage is 35V; the welding speed was 0.9 m/min. The external welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, welding wires with the diameter of 4.0mm are adopted, the current is 800A, and the voltage is 33V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 430A, and the voltage is 35V; the welding speed was 0.9 m/min.
The ultrasonic inspection: and (3) carrying out ultrasonic manual flaw detection, and detecting a welding seam with the thickness of 400mm, a repair welding seam, an opposite welding seam and a pitch adjacent to the front and the back of the opposite welding seam by 100%.
Chamfering the pipe end: and processing the bevel and the truncated edge of the end of the steel pipe.
And (3) checking the finished product: and (5) detecting the appearance quality and the external dimension of all steel pipes before final delivery of the products.
Test example 1
The Q345NS grade coil of 12X 1800mm gauge prepared in example 1 was analyzed.
The microscopic structure analysis of the different positions of the thickness of the rolled plate is that the microscopic structures of the wall thickness surface and the wall thickness center are shown in figure 1 and figure 2 respectively. The microstructure of the steel is polygonal ferrite plus pearlite, the crystal grains are uniform and fine, the crystal boundary is clear, and the grain size grade is 10.5 grade. Meanwhile, the coiled plate is observed for nonmetallic inclusions in multiple views, and almost no sharp-angled inclusions are observed; the pearls are distributed uniformly in the visual field, and no obvious strip exists.
The Q345NS steel grade coiled sheet is subjected to mechanical property analysis, and the analysis result is shown in the following table 1.
TABLE 1Q 345NS Steel grade coiled sheet mechanical property
As can be seen from Table 1, the Q345NS steel grade hot rolled coil prepared by the invention has excellent strength and toughness.
The uniform corrosion full immersion test is carried out according to two experimental conditions specified in GB/T28907-2012 standard appendix A, Q235B steel is taken as a comparison sample, and the Q235B steel is produced by adopting the same process flow as Q345NS, and comprises the following chemical components: c: 0.11%, Mn: 0.43%, Si: 0.24%, P: 0.014%, S: 0.010%, Cu: 0.02%, Cr: 0.02%, Mo: 0.004%, Ni: 0.02%, B: 0.0004%. homogeneous corrosion fully-dipped samples are shown in fig. 3 and 4, respectively, and the analytical results are shown in table 2 below.
TABLE 2 sulfuric acid corrosion performance results
As can be seen from Table 2, the Q345NS steel grade coiled sheet prepared by the invention has excellent sulfuric acid corrosion resistance.
As in fig. 3 and 4, reference numerals 1 to 3 represent the etching conditions: the temperature is 20 ℃, the sulfuric acid concentration is 20%, and the total immersion is 24h, and the reference numbers 4-6 in the figures 3 and 4 represent the corrosion conditions as follows: the temperature is 70 ℃, the concentration of sulfuric acid is 50 percent, and the whole leaching is carried out for 24 hours. As can be seen from the figure, the rolled plate prepared by the invention has slow corrosion rate in sulfuric acid and stronger sulfuric acid corrosion resistance.
Test example 2
The metallographic microstructure of the Q345NS spiral submerged arc welded pipe prepared in example 1 of the present invention was analyzed, and the metallographic microstructure of the welded joint and the heat affected zone was shown in fig. 5 and 6, respectively. As can be seen from FIG. 5, the weld structure is mainly acicular ferrite and a small amount of proeutectoid ferrite, and the acicular ferrite has high dislocation density, so that the acicular ferrite has good toughness; as can be seen from fig. 6, the hot zone structure is mainly composed of granular bainite and ferrite, and the granular bainite in the hot zone has higher strength, although the toughness is not as good as that of acicular ferrite, so as to ensure that the welded joint has good strength.
Test example 3
The mechanical properties of the spiral submerged arc welded pipe Q345NS produced in example 1 of the present invention were measured, and the results are shown in tables 3 and 4.
TABLE 3Q 345NS test results of steel pipe properties
TABLE 4 Charpy impact test results
As can be seen from tables 3 and 4, the tube body and the welding seam of the Q345NS spiral submerged arc welded tube prepared by the invention have excellent mechanical properties, and the tensile strength, the tensile strength and the like of the tube body and the welding seam meet the technical requirements of products.
The ductile-brittle transition curves of the tube body, the weld joint and the hot zone of the Q345NS spiral submerged arc welded tube are shown in fig. 7, fig. 8 and fig. 9, respectively. As can be seen from FIGS. 7-9, the ductile-brittle transition temperatures of the tube, the weld, and the hot zone reach-50 deg.C, -30 deg.C, respectively.
The Vickers hardness values of the pipe body, the welding seam and the hot zone of the Q345NS spiral submerged arc welded pipe are all relatively low and are 167HV10、164HV10、160HV10. Therefore, the Q345NS spiral submerged arc welding pipe prepared by the invention has excellent obdurability.
Test example 4
The tube body, the weld joint and the comparative sample of the Q345NS spiral submerged arc welded tube prepared in example 1 were subjected to an acid resistance test according to two test conditions specified in appendix A of the GB/T28907-2012 standard. The test data obtained by using the Q235B sample as a comparison sample and processing the comparison sample into slices of 50mm multiplied by 10mm multiplied by (2-5) mm, testing 3 parallel samples in each group according to the related requirements in JB/T7901, and analyzing the test results are shown in Table 5.
TABLE 5 sulfuric acid corrosion resistance of Q345NS spiral submerged arc welded pipe
As can be seen from Table 5, the tube body and the welding seam of the Q345NS spiral submerged arc welded tube prepared by the method have excellent sulfuric acid corrosion resistance.
The tube body and the weld corrosion fully-submerged test sample of the Q345NS spiral submerged arc welded tube are respectively shown in fig. 10 and fig. 11. It can also be seen that the pipes and welds are excellent in resistance to corrosion by sulfuric acid.
Example 2
The embodiment of the invention provides a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion, wherein a used coil comprises the following components in percentage by mass: c: 0.08%, Mn: 0.70%, Si: 0.40%, P: 0.015%, S: 0.005%, Cu: 0.40%, Cr: 0.60%, Sb: 0.07%, Ni: 0.16%, Sn: 0.0010%, B: 0.0003%, Ti: 0.023%, CEpcm: 0.18% and the balance iron and inevitable impurities.
The coil plate is smelted by a converter and refined outside the furnace, a light reduction is adopted in the continuous casting process, the coil plate is rolled by matching with a reasonable rolling and cooling control process to form a Q345NS spiral submerged arc welded pipe with the specification of 12 multiplied by 1800mm, and the outer diameter of the steel pipe is 3020 mm.
The butt welding process comprises the steps of enabling current to be 650A, enabling voltage to be 36V and enabling the diameter of a welding wire to be 4.0 mm; the welding wire is CHW-STH500 III; flux designation CHF101 NQ; the welding speed is 0.36 mm/min.
The edge milling process adopts a double edge milling process: firstly roughly milling an I-shaped groove, removing the defects of the rolled plate and crescent to control the plate width to 1780mm, and then finely milling an X-shaped groove, wherein the angle of the upper groove is 40 degrees, the angle of the lower groove is 45 degrees, and the truncated edge is 9.0 mm.
The molding process comprises the following steps: the forming process adopts three-roller forming, the three-roller forming comprises an inner forming roller and an outer forming roller, the angle of the inner forming roller is 79 degrees 10 ', the angle of the outer forming roller is 79 degrees 15', the outer forming roller comprises a 1# roller and a 3# roller, the wrap angle of the 1# roller is 13 degrees 24 ', the opening gear is 149.3mm, the wrap angle of the 3# roller is 17 degrees 16', the opening gear is 248.4mm, and the 2# roller reduction is adjusted according to the actual yield strength level of the rolled plate.
The welding procedure comprises an inner welding procedure and an outer welding procedure, double-wire serial submerged arc automatic welding is adopted, the welding wire is CHW-STH500 III, and the welding wire comprises the following chemical components: c: 0.083%, Mn: 1.32%, Si: 0.181%, P: 0.012%, S: 0.004%, Cu: 0.238%, Cr: 0.61%, Ni: 0.36 percent; the flux is CHF101NQ, and deposited metal comprises the following chemical components: c: 0.070%, Mn: 1.45%, Si: 0.32%, P: 0.021%, S: 0.009%, Cu: 0.214%, Cr: 0.55%, Ni: 0.541 percent. The internal welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, a welding wire with the diameter of 4.0mm is adopted, the current is 710A, and the voltage is 33V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 440A, and the voltage is 38V; the welding speed was 1.0 m/min. The external welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, welding wires with the diameter of 4.0mm are adopted, the current is 820A, and the voltage is 34V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 440A, and the voltage is 38V; the welding speed was 1.0 m/min.
The ultrasonic inspection: and (3) carrying out ultrasonic manual flaw detection, and detecting a welding seam with the thickness of 400mm, a repair welding seam, an opposite welding seam and a pitch adjacent to the front and the back of the opposite welding seam by 100%.
Chamfering the pipe end: and processing the bevel and the truncated edge of the end of the steel pipe.
And (3) checking the finished product: and (5) detecting the appearance quality and the external dimension of all steel pipes before final delivery of the products.
Example 3
The embodiment of the invention provides a Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion, wherein a used coil comprises the following components in percentage by mass: c: 0.06%, Mn: 1.20%, Si: 0.28%, P: 0.014%, S: 0.005%, Cu: 0.20%, Cr: 1.00%, Sb: 0.06%, Ni: 0.15%, Sn: 0.015%, B: 0.0004%, Ti: 0.018%, CEpcm: 0.19%, and the balance of iron and inevitable impurities.
The coil plate is smelted by a converter and refined outside the furnace, the specification of the coil plate rolled by adopting light reduction and matching with a reasonable rolling and cooling control process in the continuous casting process is 12 multiplied by 1800mm, and a Q345NS spiral submerged arc welded pipe with the outer diameter of the steel pipe being 3020mm is prepared.
The butt welding process comprises the steps of enabling current to be 650A, enabling voltage to be 36V and enabling the diameter of a welding wire to be 4.0 mm; the welding wire is CHW-STH500 III; flux designation CHF101 NQ; the welding speed is 0.36 mm/min.
The edge milling process adopts a double edge milling process: firstly roughly milling an I-shaped groove, removing the defects of the rolled plate and crescent to control the plate width at 1790mm, and then finely milling an X-shaped groove, wherein the angle of the upper groove is 38 degrees, the angle of the lower groove is 42 degrees, and the truncated edge is 7.0 mm.
The molding process comprises the following steps: the forming process adopts three-roller forming, the three-roller forming comprises an inner forming roller and an outer forming roller, the angle of the inner forming roller is 79 degrees 10 ', the angle of the outer forming roller is 79 degrees 15', the outer forming roller comprises a 1# roller and a 3# roller, the wrap angle of the 1# roller is 13 degrees 24 ', the opening gear is 149.3mm, the wrap angle of the 3# roller is 17 degrees 16', the opening gear is 248.4mm, and the 2# roller reduction is adjusted according to the actual yield strength level of the rolled plate.
The welding procedure comprises an inner welding procedure and an outer welding procedure, double-wire serial submerged arc automatic welding is adopted, the welding wire is CHW-STH500 III, and the welding wire comprises the following chemical components: c: 0.083%, Mn: 1.32%, Si: 0.181%, P: 0.012%, S: 0.004%, Cu: 0.238%, Cr: 0.61%, Ni: 0.36 percent; the flux is CHF101NQ, and deposited metal comprises the following chemical components: c: 0.070%, Mn: 1.45%, Si: 0.32%, P: 0.021%, S: 0.009%, Cu: 0.214%, Cr: 0.55%, Ni: 0.541 percent. The internal welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, a welding wire with the diameter of 4.0mm is adopted, the current is 590A, and the voltage is 29V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 360A, and the voltage is 34V; the welding speed was 0.8 m/min. The external welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, welding wires with the diameter of 4.0mm are adopted, the current is 680A, and the voltage is 30V; the second wire is an alternating current positive connection, a welding wire with the diameter of 3.2mm is adopted, the current is 360A, and the voltage is 34V; the welding speed was 0.8 m/min.
The ultrasonic inspection: and (3) carrying out ultrasonic manual flaw detection, and detecting a welding seam with the thickness of 400mm, a repair welding seam, an opposite welding seam and a pitch adjacent to the front and the back of the opposite welding seam by 100%.
Chamfering the pipe end: and processing the bevel and the truncated edge of the end of the steel pipe.
And (3) checking the finished product: and (5) detecting the appearance quality and the external dimension of all steel pipes before final delivery of the products.
The performance of the spiral submerged arc welded pipe Q345NS prepared in example 2 and example 3 is tested, and the mechanical property and the sulfuric acid corrosion resistance are similar to those of the test result of example 1, thereby showing that the spiral submerged arc welded pipe Q345NS provided by the invention has excellent toughness and excellent sulfuric acid corrosion resistance.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A Q345NS spiral submerged arc welded pipe for resisting sulfuric acid dew point corrosion is characterized in thatIn the following steps: the welded pipe comprises the following chemical components in percentage by mass: c is less than or equal to 0.10 percent, Mn: 0.70-1.20%, Si is less than or equal to 0.45%, P is less than or equal to 0.020%, S is less than or equal to 0.008%, Cu: 0.20-0.40%, Cr: 0.60% -1.00%, Sb: 0.05-0.10%, Ni is less than or equal to 0.25%, Sn is less than or equal to 0.015%, B is less than or equal to 0.0005%, Ti: 0.01 to 0.05%, CEpcmLess than or equal to 0.20 percent, and the balance of iron and inevitable impurities.
2. The method for producing a spiral submerged arc welded pipe for sulfuric acid dew point corrosion resistance Q345NS according to claim 1, comprising: the manufacturing method comprises an edge milling process, a forming process and a welding process, wherein the forming process forms the strip steel into a spiral cylinder according to a forming angle of 79 degrees 12'.
3. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 2, wherein: the forming process adopts three-roller forming, the three-roller forming comprises an inner forming roller and an outer forming roller, the angle of the inner forming roller is 79 degrees 10 ', the angle of the outer forming roller is 79 degrees 15', the outer forming roller comprises a 1# roller and a 3# roller, the wrap angle of the 1# roller is 13 degrees 24 ', the opening gear is 149.3mm, and the wrap angle of the 3# roller is 17 degrees 16', and the opening gear is 248.4 mm.
4. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 2, wherein: the edge milling process adopts a double edge milling process: firstly roughly milling an I-shaped groove, and then finely milling an X-shaped groove, wherein the angle of the upper groove is 35-40 degrees, the angle of the lower groove is 40-45 degrees, and the truncated edge is 7.0-9.0 mm.
5. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 2, wherein: the submerged arc welding wire adopted in the welding procedure comprises the following chemical components in percentage by mass: c is less than or equal to 0.12 percent, Mn: 1.0-1.60%, Si is less than or equal to 0.35%, P is less than or equal to 0.025%, S is less than or equal to 0.020%, Cu: 0.20-0.50%, Cr: 0.30% -0.90%, Ni: 0.20 to 0.80 percent, and the balance of Fe.
6. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 2, wherein: the welding process adopts the welding flux which comprises the following chemical components in percentage by mass: less than or equal to 0.15 percent of C, less than or equal to 1.50 percent of Mn, less than or equal to 0.35 percent of Si, less than or equal to 0.025 percent of P, less than or equal to 0.020 percent of S, Cu: 0.20-0.50%, Cr: 0.30% -1.20%, Ni: 0.20 to 0.80 percent, and the balance of Fe.
7. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 2, wherein: the welding procedure comprises an inner welding procedure and an outer welding procedure, wherein the inner welding procedure adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, the current is 590A-710A, and the voltage is 29V-33V; the second wire is in AC positive connection, the current is 360A-440A, and the voltage is 34V-38V; the welding speed is 0.8-1.0 m/min.
8. The method for manufacturing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to claim 7, wherein: the external welding process adopts double-wire serial submerged arc automatic welding, the first wire is in direct current reverse connection, the current is 680A-820A, and the voltage is 30V-34V; the second wire is in AC positive connection, the current is 360A-440A, and the voltage is 34V-38V; the welding speed is 0.8-1.0 m/min.
9. The method for producing a spiral submerged arc welded pipe of Q345NS for resisting sulfuric acid dew point corrosion according to any one of claims 2 to 8, wherein: the diameter of the spiral submerged arc welded pipe is 3020mm, and the wall thickness is 12 mm.
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