Development process of a wear-resistant dredging pipe

Abstract

The invention belongs to the field of dredging engineering, in particular to the field of B23P15 / 00, and more specifically to a development process of a wear-resistant dredging pipe. The development process of the wear-resistant dredging pipe includes: wear-resistant steel plate inspection, layout and blanking, cutting and beveling, pre-bending, coiling, longitudinal seam welding, and rounding. The chemical composition of the wear-resistant steel plate is 0.1-0.2% C, 0.1-0.2% Si, 0.6-0.8% Mn, 0.001-0.1% P, 0.001-0.01S, 0.3-0.5% Cu, 0.2-0.3% Ni, 0.5-0.6% Cr, 0.01-0.1% Nb, 0.01-0.1% Al, 0.01-0.1% Ti, 0.1-0.3% Mo, 0.001-0.1% B, 0.001-0.01% N and the balance Fe. The resulting wear-resistant dredging pipe has excellent wear resistance and corrosion resistance, with low corrosion and wear components, and its wear resistance level is about twice that of Q235B steel plate.

Description

Technical Field

[0001] The invention belongs to the field of dredging engineering, in particular to the field of B23P15 / 00, and more specifically to a development process of a wear-resistant dredging pipe. Background Art

[0002] Dredging pipelines are commonly used in projects such as silt removal and transportation, port construction, land reclamation, and flood control. Waterway dredging involves large volumes of slurry, long distances, and high sand and gravel content. Due to the unique application environment of dredging pipelines, they are subject to impact and friction from floating objects, debris, and extreme weather. Rapid flow of slurry containing sharp-edged gravel within the pipelines can cause significant wear and tear. This can damage the pipeline material over time, severely impacting its service life. Common dredging pipeline materials such as Q235B and Q345B typically have a service life of less than one year. Furthermore, repair of dredging pipelines is difficult and costly. Therefore, wear resistance has become a major constraint on the further development of dredging equipment.

[0003] Prior art: CN107825070B discloses a method for processing dredging pipes, which mainly includes welding a steel mesh to the inner wall of the base pipe, spraying an adhesive to form a steel mesh, centrifugally spraying a polymer wear-resistant layer, and co-curing the wear-resistant layer adhesive. This processing method can solve the problem of easy separation between the wear-resistant layer and the base layer, but the wear resistance of the composite layer may be relatively poor. Prior art: CN102517509A discloses an HB500-grade wear-resistant steel plate and its preparation method. The main component of this wear-resistant steel plate is a carbon-manganese-iron alloy, which has relatively excellent wear resistance. However, the corrosion resistance of the steel plate is ignored when it is involved, which will affect its scope of application to a certain extent. Therefore, it is of great practical significance to develop a wear-resistant dredging pipe suitable for waterway transportation with excellent wear and corrosion resistance. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a process for producing a wear-resistant dredging pipe, which comprises the following steps:

[0005] S1. Wear-resistant steel plate inspection: Check the size of the wear-resistant steel plate, and check whether the thickness and allowable deviation of the steel plate meet the requirements;

[0006] S2. Lofting and cutting: CNC plasma thermal cutting is used for lofting and cutting. The steel plate cutting length and diagonal deviation shall not exceed 2mm, and the cutting speed shall be 1000-1500mm / min;

[0007] S3. Beveling: After setting out and cutting, plasma arc cutting is used to cut the bevel of the plate seam edge. The cutting gun is rotated 25-30 degrees during cutting, leaving a blunt edge of 3-5mm. After cutting the bevel, remove impurities on the edge of the cut, and grind the uneven parts until there are no cracks and missing edges on the bevel surface.

[0008] S4. Pre-bending: Use a hydraulic press to pre-bend the wear-resistant steel plate;

[0009] S5. Rolling: Insert the wear-resistant steel plate between the upper and lower rollers of the three-roller pipe rolling machine. Use a 90° angle ruler to measure so that the longitudinal edge of the plate is perpendicular to the roller. Start the pipe rolling machine, lower the upper roller to press the steel plate, and then rotate the upper and lower rollers to roll back and forth until the two ends of the steel plate touch each other. Use a special F wrench to adjust the end face, longitudinal joint surface and pipe end to be flush and without misalignment, and then spot weld them firmly. The spot welding should follow the principle of spot welding the ends of the pipe first and then the middle. Each weld point is 30-50mm long and the interval between weld points is 200-300mm. The thickness of the spot weld should not exceed 70% of the pipe wall thickness, and the arc pit should be filled. If there are pores or cracks on the spot weld surface, they must be cleaned and re-welded until the standard is met.

[0010] S6. Longitudinal seam welding: Multi-layer and multi-pass welding is used for longitudinal seam welding, which includes base layer welding, filling layer welding, and cover layer welding;

[0011] S7. Rounding: The pipe section after longitudinal seam welding shall be rolled and rounded twice. During rolling, it shall be inspected with template and tape measure. If the inspection is qualified, the wear-resistant dredging pipe shall be obtained. The arc length of the rounding template for pipe section rolling shall be 1 / 6-1 / 4 of the circumference of the pipe. The gap between the template and the inner wall of the pipe shall comply with the following regulations: the longitudinal weld joint shall not be greater than 10% of the wall thickness plus 2-4mm; the butt weld 200mm away from the pipe end shall not be greater than 3mm.

[0012] Preferably, the welding current of the base layer welding is 140-160A, the arc voltage is 18-22V, the welding speed is 20-30cm / min, the shielding gas flow rate is 16-18L / min, and the interlayer temperature does not exceed 200°C.

[0013] Preferably, the welding current of the filling layer welding is 160-180A, the arc voltage is 20-25V, the welding speed is 30-40cm / min, the shielding gas flow rate is 16-20L / min, and the interlayer temperature does not exceed 200°C.

[0014] Preferably, the welding current of the cover layer is 150-200A, the arc voltage is 20-25V, the welding speed is 30-40cm / min, the shielding gas flow rate is 16-20L / min, and the interlayer temperature does not exceed 200°C.

[0015] The present invention adopts a multi-layer and multi-pass welding method to perform longitudinal seam welding, including base layer welding, filling layer welding, and cover layer welding, and further limits the welding current, arc voltage, welding speed, shielding gas flow rate, and inter-layer temperature, which can improve the physical properties of the wear-resistant dredging pipe, especially the wear resistance and corrosion resistance. This is because the rear layer weld has a heat treatment effect on the front layer weld, which is equivalent to a normalizing treatment of the front layer weld, thereby improving the wear resistance and corrosion resistance. In addition, the present invention selects a specific welding current and arc voltage. The welding current of the base layer welding is 140-160A, and the arc voltage is 18-22V; the welding current of the filling layer welding is 160-180A, and the arc voltage is 20-25V; the welding current of the cover layer is 150-200A, and the arc voltage is 20-25V. The matching of the welding current and the welding voltage can ensure that the wire feeding speed and the melting capacity of the welding wire by the welding voltage are consistent, thereby ensuring the stability of the arc length. It can not only ensure that the welding efficiency is improved, the fusion between the welds is good, and the welds are well formed, but also prevent the current from being too large and thus piercing the workpiece, thereby ensuring the safety and efficiency of the longitudinal weld.

[0016] Preferably, the production process of the wear-resistant steel plate in the step S1 is: M1, molten iron pretreatment; M2, 120-ton converter smelting; M3, ladle refining furnace refining; M4, molten steel vacuum circulation degassing method refining; M5, slab continuous casting; M6, slow cooling; M7, rolling; M8, slow cooling of rolled material; M9, heat treatment.

[0017] Preferably, the raw materials for preparing the wear-resistant steel plate include: C, Si, Mn, P, S, Cu, Ni, Cr, Nb, Al, Ti, Mo, B, N, and Fe.

[0018] Further preferably, the raw materials for preparing the wear-resistant steel plate include, by mass percentage, 0.1-0.2% C, 0.1-0.2% Si, 0.6-0.8% Mn, 0.001-0.1% P, 0.001-0.01S%, 0.3-0.5% Cu, 0.2-0.3% Ni, 0.3-0.6% Cr, 0.01-0.1% Nb, 0.01-0.1% Al, 0.01-0.1% Ti, 0.1-0.3% Mo, 0.001-0.1% B, 0.001-0.01% N, and the balance is Fe.

[0019] As an implementable case, the raw materials for preparing the molten iron may include, by mass percentage, 0.186% C, 0.16% Si, 0.74% Mn, 0.01% P, 0.0013S%, 0.4% Cu, 0.26% Ni, 0.56% Cr, 0.02% Nb, 0.035% Al, 0.016% Ti, 0.202% Mo, 0.0016% B, 0.005%, 97.4014% Fe.

[0020] The invention selects specific chemical components as raw materials for preparing the wear-resistant steel plate, which are 0.1-0.2% C, 0.1-0.2% Si, 0.6-0.8% Mn, 0.001-0.1% P, 0.001-0.01S, 0.3-0.5% Cu, 0.2-0.3% Ni, 0.5-0.6% Cr, 0.01-0.1% Nb, 0.01-0.1% Al, 0.01-0.1% Ti, 0.1-0.3% Mo, 0.001-0.1% B, 0.001-0.01% N and the balance Fe in percentage by mass. The prepared wear-resistant steel plate has excellent wear resistance and corrosion resistance, as well as excellent mechanical properties. Chromium (Cr) increases the hardenability of wear-resistant steel plates and acts as a secondary hardener, improving their hardness and wear resistance without making them brittle. It also improves their hardenability, giving them better mechanical properties after quenching and tempering. It can also form chromium-containing carbides in carburized steel, thereby improving the wear resistance of the material surface. When the chromium content in the non-ferrous components exceeds 12%, the wear-resistant steel plate exhibits excellent high-temperature oxidation resistance and oxidative corrosion resistance, while also increasing its thermal strength, strength, and hardness and reducing its elongation and reduction of area. When the chromium content in the non-ferrous components exceeds 23%, strength and hardness decrease, while elongation and reduction of area increase accordingly. Chromium-containing steel plates can easily achieve higher surface quality after grinding. Nickel (Ni) strengthens ferrite and refines pearlite in wear-resistant steel plates, improving strength without affecting the plasticity of the material. A certain nickel content can increase the strength of steel without significantly reducing its toughness. Every 1% increase in nickel can increase the strength by approximately 29.4 Pa. As the nickel content increases, the yield strength of the wear-resistant steel plate increases faster than the tensile strength. While nickel improves the strength of steel, it has less damage to the toughness, plasticity and other process properties of steel than other alloying elements. Nickel can also improve the wear-resistant steel plate's resistance to fatigue and reduce the steel's sensitivity to notches, lower the low-temperature brittle transition temperature of steel, and improve the performance of dredging pipelines at low temperatures. Molybdenum (Mo) in wear-resistant steel plates can improve hardenability and heat resistance, prevent temper brittleness, increase remanence and coercive force, as well as corrosion resistance in certain media. Nickel can also improve the tempering resistance or tempering stability of steel plates, reduce the tendency of carbides to form a continuous network on the grain boundaries in the carburized layer, reduce the residual austenite in the carburized layer, and relatively increase the wear resistance of the surface layer, so that parts can be tempered at a higher temperature, thereby more effectively reducing residual stress and improving plasticity. In addition, the medium transported by dredging pipelines includes seawater containing a large amount of inorganic salts. A certain amount of molybdenum can prevent the pitting corrosion tendency of corrosive anions such as chloride ions in seawater on the pipeline, thereby improving the wear resistance and corrosion resistance of dredging pipelines.Titanium, boron, aluminum, etc. can make the wear-resistant steel plate have better strength and corrosion resistance. The wear-resistant steel plate prepared by the above chemical components has excellent wear resistance and corrosion resistance, and the values ​​of corrosion component and wear component are small. After welding by multi-pass multi-layer welding method, its corrosion resistance is about twice that of Q235B steel plate.

[0021] Preferably, the M7 rolling step includes: L1, continuous casting billet heating; L2, descaling; L3, rough rolling; L4, finishing rolling; L5, hot straightening; L6, steel plate marking; L7, cooling bed; L8, shearing; L9, marking; L10, quenching and tempering; L11, stacking and warehousing.

[0022] Preferably, the M9 heat treatment step includes quenching and tempering, the quenching temperature is 850-1000°C, and the quenching time is 8-15min; the tempering temperature is 200-240°C, and the tempering time is 8-15min; as an implementable case, the quenching temperature may include 850°C, 900°C, 950°C or 1000°C, and the quenching time may include 8min, 10min, 12min or 15min; the tempering temperature may include 200°C, 210°C, 220°C, 230°C or 240°C, and the tempering time may include 8min, 10min, 12min or 15min.

[0023] The heat treatment steps described in the present invention include quenching and tempering, wherein the quenching temperature is 850-1000℃, the quenching time is 8-15min, and the quenching is to heat the wear-resistant steel plate and immerse it in a coolant. After cooling treatment, the performance of the wear-resistant steel plate will be better and more stable, and the hardness and wear resistance can be improved. The quenching temperature described in the present invention is determined according to the phase transition point of the material component of the wear-resistant steel plate. If the quenching temperature is lower than 850℃, the wear-resistant steel plate cannot reach the phase transition temperature, and the quenching requirements cannot be met. No matter how good the cooling is, the wear-resistant steel plate cannot be hardened. If the quenching heating temperature is higher than 1000℃, the matrix grains will be coarse, the structure will be coarsened, the residual austenite will increase, the toughness will be significantly deteriorated, and the steel plate will be easily deformed or cracked. More seriously, the grain boundaries of the material will melt, and the wear-resistant steel plate will be difficult to use normally. When the quenching temperature is too high, the wear-resistant steel plate will be difficult to use normally. The temperature is 850-1000℃, and the quenching time is 8-15min. Due to the phase change temperature range, the mechanical strength of the wear-resistant steel plate can be significantly increased and the service life is prolonged. In order to make the wear-resistant steel plate more stable, tempering is carried out after quenching. If the tempering temperature is lower than 200℃, the decomposition rate of martensite is low, the high-density dislocations are not restored, the microstructure is still bundled strip martensite, the strength of the steel plate is high, and the elongation is low. If the tempering temperature is higher than 240℃, its strength and internal stress decrease, and the plasticity and toughness increase. Only when the tempering temperature is 200-240℃ and the tempering time is 8-15min, the stability of the wear-resistant steel plate organization can be improved, the internal stress is eliminated, it is not easy to deform or crack, it has higher hardness, strength, plasticity and toughness, and the wear resistance is improved to a certain extent.

[0024] Beneficial effects

[0025] (1) In the present invention, through a specific development process including: wear-resistant steel plate inspection, layout and blanking, cutting grooves, pre-bending, rolling, longitudinal seam welding, and rounding, the obtained wear-resistant dredging pipe has excellent wear resistance and corrosion resistance, low corrosion component and wear component, and the wear resistance level is about twice that of Q235B steel plate.

[0026] (2) In the present invention, the chemical composition of the wear-resistant steel plate is 0.1-0.2% C, 0.1-0.2% Si, 0.6-0.8% Mn, 0.001-0.1% P, 0.001-0.01S%, 0.3-0.5% Cu, 0.2-0.3% Ni, 0.5-0.6% Cr, 0.01-0.1% Nb, 0.01-0.1% Al, 0.01-0.1% Ti, 0.1-0.3% Mo, 0.001-0.1% B, 0.001-0.01% N and the balance Fe. The developed wear-resistant steel plate has excellent mechanical properties and excellent wear resistance and corrosion resistance.

[0027] (3) In the present invention, a single-layer wear-resistant steel plate is selected for the preparation of the wear-resistant dredging pipe, avoiding the method of spraying the wear-resistant layer on the inner wall of the dredging pipe, which can ensure that the wear-resistant dredging pipe can still work normally under the impact of mud and sand slurry, and the dredging pipe will not be unable to be used normally due to the shedding of the wear-resistant layer.

[0028] (4) In the present invention, a multi-layer and multi-pass welding method is adopted, including base layer welding, filling layer welding, and cover layer welding, which can improve the physical properties of the wear-resistant dredging pipe, especially the wear resistance and corrosion resistance, improve the welding efficiency, and achieve good fusion between welds.

[0029] (5) In the present invention, the heat treatment step includes quenching and tempering at a specific temperature and time, which can improve the stability of the structure and eliminate the internal stress of the wear-resistant steel plate. The wear-resistant steel plate is not easy to deform and crack, and has higher wear resistance and mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the wear-resistant dredging pipe prepared in Example 1, wherein: 1-flange one; 2-flange two; 3-wear-resistant pipe body; 4-reinforcement rib plate.

[0031] Figure 2 Schematic diagram of cutting the groove in Example 1.

[0032] Figure 3 The microstructure diagram of the wear-resistant dredging pipe prepared in Example 1, wherein (a): metallographic structure diagram; (b): SEM structure diagram; (c): TEM structure diagram; (d): EBSD structure diagram; (e): STEM diagram + precipitated phase energy spectrum diagram; (f): carbide TEM diagram.

[0033] Figure 4 This is a schematic diagram of pre-bending in Example 1, wherein 5 is the lower membrane, 6 is the wear-resistant steel plate, and 7 is the upper membrane.

[0034] Figure 5 This is the weld-fusion line-matrix structure evolution diagram of the wear-resistant dredging pipe prepared in Example 1.

[0035] Figure 6 This is a diagram showing the hardness change at the steel weld of the wear-resistant dredging pipe prepared in Example 1.

[0036] Figure 7 is the corrosion component diagram of Example 1 and Comparative Example 1, where W t is the total weight loss, W c is the corrosion component, W e The 3 groups of data on the left are for Example 1, and the 3 groups of data on the right are for Comparative Example 1.

[0037] Figure 8is the wear component diagram of Example 1 and Comparative Example 1, where W e is the wear component, W e 0 is the wear amount in the pure wear experiment, W e c The wear component promoted by corrosion is shown in FIG1 . The three groups of data on the left are Example 1, and the three groups of data on the right are Comparative Example 1.

[0038] Figure 9 This is the erosion-corrosion morphology diagram of Example 1. Three test points were taken on the wear-resistant dredging pipe. After rust removal, the state of the test surface after erosion is more clearly shown.

[0039] Figure 10 For the erosion corrosion morphology diagram of Example 1, three test points were taken on the Q235 steel plate, and the state of the test surface after erosion was more clearly shown after rust removal. DETAILED DESCRIPTION

[0040] Example 1

[0041] This embodiment provides a process for producing a wear-resistant dredging pipe, and the process comprises the following steps:

[0042] S1. Wear-resistant steel plate inspection: Check the size of the wear-resistant steel plate, and check whether the thickness and allowable deviation of the steel plate meet the requirements;

[0043] S2. Lofting and cutting: CNC plasma thermal cutting is performed, the steel plate cutting length and diagonal deviation does not exceed 2mm, and the cutting speed is 1200mm / min;

[0044] S3. Beveling: After setting out and cutting, plasma arc cutting is used to cut the bevel of the plate seam edge. The cutting gun is rotated 30 degrees during cutting, leaving a 3mm blunt edge on the bevel. After cutting the bevel, remove impurities on the edge of the cut, and grind the uneven parts until there are no cracks and missing edges on the bevel surface.

[0045] S4. Pre-bending: Use a hydraulic press to pre-bend the wear-resistant steel plate. Before pre-bending, prepare the upper and lower pressing films that match the curvature of the pipe and install them on the hydraulic press workbench. The pressing film width is 360mm. During the pre-bending process, use a template to check the pre-bending arc. The gap between the pre-bending arc and the inspection template h is ≤ 1mm to ensure the geometric shape and dimensional accuracy of the steel pipe weld area. After pre-bending, the bending radius of the plate edge reaches the radius of the steel pipe. The bending width of both sides is equal, the bending degree is consistent, and they are symmetrical and parallel. After pre-bending, there is no sharp bend or wavy shape on the plate edge.

[0046] S5. Coiling: Insert the steel plate between the upper and lower rollers of the three-roller pipe reel. Use a 90° angle ruler to measure so that the longitudinal edge of the plate is perpendicular to the rollers. Start the pipe reel and lower the upper roller to press the steel plate. Then rotate the upper and lower rollers to roll back and forth until the two ends of the steel plate touch each other. Use a special F wrench to adjust the end face, longitudinal joint surface and pipe end to be flush and without misalignment, then spot weld them firmly. Spot welding should follow the principle of spot welding the ends of the pipe first and then the middle. Each weld is 40mm long and 240mm apart. The spot weld thickness is 60% of the thickness and the arc crater is filled. If any pores or cracks are found on the spot weld surface, they must be cleaned and re-welded until the standard is met.

[0047] S6. Longitudinal seam welding: Multi-layer and multi-pass welding is used for longitudinal seam welding, which includes base layer welding, filling layer welding, and cover layer welding;

[0048] S7. Rounding: The pipe section with longitudinal seam welded is rolled and rounded twice. During rolling, it is inspected with template and tape measure. If the inspection is qualified, the wear-resistant dredging pipe is obtained. The arc length of the rounding template for rolling the pipe should be 1 / 6 of the circumference of the pipe: 8% of the wall thickness plus 2mm at the butt longitudinal weld; 2mm at the butt weld 200mm away from the pipe end.

[0049] The base layer welding current is 150A, the arc voltage is 20V, the welding speed is 25cm / min, the shielding gas flow rate is 16L / min, and the interlayer temperature is 190°C.

[0050] The filling layer welding current is 170A, the arc voltage is 24V, the welding speed is 35cm / min, the shielding gas flow rate is 18L / min, and the interlayer temperature is 190°C.

[0051] The cap layer welding current is 180A, the arc voltage is 24V, the welding speed is 35cm / min, the shielding gas flow rate is 18L / min, and the interlayer temperature is 190°C.

[0052] The production process of the wear-resistant steel plate in the step S1 is as follows: M1, molten iron pretreatment; M2, 120-ton converter smelting; M3, ladle refining furnace refining; M4, molten steel vacuum circulation degassing method refining; M5, slab continuous casting; M6, slow cooling; M7, rolling; M8, rolled material slow cooling; M9, heat treatment.

[0053] The raw materials for preparing the molten iron are as follows by mass percentage: 0.186% C, 0.16% Si, 0.74% Mn, 0.01% P, 0.0013S, 0.4% Cu, 0.26% Ni, 0.56% Cr, 0.02% Nb, 0.035% Al, 0.016% Ti, 0.202% Mo, 0.0016% B, 0.005%, and 97.4014% Fe.

[0054] The M7 rolling steps include: L1, continuous casting billet heating; L2, descaling; L3, rough rolling; L4, finishing rolling; L5, hot straightening; L6, steel plate marking; L7, cooling bed; L8, shearing; L9, marking; L10, quenching and tempering; L11, stacking and warehousing; the thickness of the continuous casting billet is 250mm, and the rolling process is divided into 15 passes. The first 7 passes are rough rolling, and the starting rolling temperature is 1174℃. The last 8 passes are finishing rolling, and the starting rolling temperature is set to 1000℃. The final rolling temperature is 873℃, the starting cooling temperature is 756℃, and the final cooling temperature is 663℃.

[0055] The M9 heat treatment step includes quenching and tempering. The quenching temperature is 910° C. and the quenching time is 10 minutes; the tempering temperature is 220° C. and the tempering time is 10 minutes.

[0056] The schematic diagram of the wear-resistant dredging pipe prepared in Example 1 is as follows Figure 1 As shown, 1-flange one; 2-flange two; 3-wear-resistant pipe body; 4-reinforcement rib plate.

[0057] The schematic diagram of cutting the groove in Example 1 is as follows Figure 2 shown.

[0058] The microstructure of the wear-resistant dredging pipe prepared in Example 1 is shown in FIG. Figure 3 As shown, where (a): metallographic organization diagram; (b): SEM organization diagram, (c): TEM organization diagram; (d): EBSD organization diagram; (e): STEM+precipitation phase energy spectrum diagram; (f): carbide TEM diagram.

[0059] The schematic diagram of pre-bending in Example 1 is as follows Figure 4 As shown, 1-lower membrane, 2-wear-resistant steel plate, 3-upper membrane.

[0060] The weld-fusion line-matrix structure evolution diagram of the wear-resistant dredging pipe prepared in Example 1 is as follows: Figure 5 shown.

[0061] The hardness change of the steel weld of the wear-resistant dredging pipe prepared in Example 1 is shown in the figure below: Figure 6 shown.

[0062] The erosion corrosion morphology of Example 1 is shown in FIG. Figure 9 As shown, three test points were taken on the wear-resistant dredging pipe, and the state of the test surface after scouring was more clearly shown after rust removal.

[0063] Comparative Example 1

[0064] The steel plate provided in this comparative example is made of Q235B material.

[0065] The corrosion components of Example 1 and Comparative Example 1 are shown in FIG. Figure 7 As shown, where W t is the total weight loss, W c is the corrosion component, W e The wear component.

[0066] The wear components of Example 1 and Comparative Example 1 are shown in FIG. Figure 8 As shown, where W e is the wear component, W e 0 is the wear amount in the pure wear experiment, W e c The wear component promoted by corrosion.

[0067] The erosion corrosion morphology of comparative example 1 is shown in FIG. Figure 10 As shown in the figure, three test points were taken on the Q235 steel plate, and the state of the test surface after scouring was more clearly shown after rust removal.

[0068] Performance Testing

[0069] 1. Mechanical properties testing

[0070] Test object: the wear-resistant dredging pipe prepared in Example 1, and the test results are recorded in Table 1

[0071] 2. Hardness change test at weld

[0072] Test object: wear-resistant dredging pipe prepared in Example 1, test results are as follows Figure 6 shown

[0073] Test method: Draw lines parallel to the weld at different positions, evenly select multiple points on each line to measure the hardness, and take the average value as the average hardness at that distance. After obtaining the average hardness at multiple distances, record it in a table. 3. Wear and corrosion resistance test

[0074] Test objects: wear-resistant steel plate prepared in Example 1, Q235B steel plate in Comparative Example 1

[0075] The test conditions are shown in Table 2, and the results are shown in Figure 7-10 As shown, the size of the wear-resistant steel plate is 25mm×25mm×3mm; the test environment is seawater with a pH of about 8, the size and content of sea sand are 20-30 mesh, the mass fraction is 3%, and the seawater test flow rate is 6.5m / s. The wear-resistant steel plate prepared in Example 1 and the Q235B steel plate of Comparative Example 1 were washed in the above seawater environment for 5 hours, and then the wear and corrosion resistance of the steel plates were tested.

[0076] Table 1

[0077]

[0078] Table 2

[0079] Experimental parameters Sample size 25mm×25mm×3mm Test solution Artificial seawater Solution pH Around 8 Size and content of sea sand 20-30 mesh, 3% (mass fraction) Experimental flow rate 6.5m / s Testing cycle 5h

Claims

1. A process for developing a wear-resistant dredging pipe, characterized in that: The development process includes the following steps: S1. Wear-resistant steel plate inspection: Check the size of the wear-resistant steel plate, and check whether the thickness and allowable deviation of the steel plate meet the requirements; S2. Lofting and cutting: CNC plasma thermal cutting method is used for lofting and cutting. The length and diagonal deviation of the steel plate are no more than 2mm, and the cutting speed is 1000-1500mm / min; S3. Beveling: After setting out and cutting, plasma arc cutting is used to cut the bevel of the plate seam edge. The cutting gun is rotated 25-30 degrees during cutting, leaving a blunt edge of 3-5mm. After cutting the bevel, remove impurities on the edge of the cut, and grind the uneven parts until there are no cracks and missing edges on the bevel surface. S4. Pre-bending: Use a hydraulic press to pre-bend the wear-resistant steel plate; S5. Rolling: Insert the wear-resistant steel plate between the upper and lower rollers of the three-roller pipe rolling machine. Use a 90° angle ruler to measure so that the longitudinal edge of the plate is perpendicular to the roller. Start the pipe rolling machine, lower the upper roller to press the steel plate, and then rotate the upper and lower rollers to roll back and forth until the two ends of the steel plate touch each other. Use a special F wrench to adjust the end face, longitudinal joint surface and pipe end to be flush and without misalignment, and then spot weld them firmly. The spot welding should follow the principle of spot welding the ends of the pipe first and then the middle. Each weld point is 30-50mm long and the interval between weld points is 200-300mm. The thickness of the spot weld should not exceed 70% of the pipe wall thickness, and the arc pit should be filled. If pores or cracks are found on the spot weld surface, they must be removed and re-welded until the standard is met. S6. Longitudinal seam welding: Multi-layer and multi-pass welding is used for longitudinal seam welding, which includes base layer welding, filling layer welding, and cover layer welding; S7. Rounding: The pipe section after longitudinal seam welding shall be rolled twice to round it. During rolling, it shall be inspected with a template and a tape measure. If the inspection is qualified, the wear-resistant dredging pipe shall be obtained. The arc length of the rounding template for the pipe section rolling shall be 25% of the circumference of the pipe. The gap between the template and the inner wall of the pipe shall meet the following requirements: the gap between the longitudinal weld joint shall not be greater than 10% of the wall thickness plus 2-4mm; the gap between the butt weld 200mm away from the pipe end shall not be greater than 3mm. The production process of the wear-resistant steel plate in step S1 is as follows: M1, molten iron pretreatment; M2, 120-ton converter smelting; M3, ladle refining furnace refining; M4, molten steel vacuum circulation degassing refining; M5, slab continuous casting; M6, slow cooling; M7, rolling; M8, rolled material slow cooling; M9, heat treatment; The raw materials for preparing the wear-resistant steel plate include, by mass percentage, 0.1-0.2% C, 0.1-0.2% Si, 0.6-0.8% Mn, 0.001-0.1% P, 0.001-0.01S%, 0.3-0.5% Cu, 0.2-0.3% Ni, 0.3-0.6% Cr, 0.01-0.1% Nb, 0.01-0.1% Al, 0.01-0.1% Ti, 0.1-0.3% Mo, 0.001-0.1% B, 0.001-0.01% N, and the balance is Fe; The M9 heat treatment step includes quenching and tempering; The quenching temperature is 850-1000° C., and the quenching time is 8-15 minutes; the tempering temperature is 200-240° C., and the tempering time is 8-15 minutes.

2. The process for producing the wear-resistant dredging pipe according to claim 1, characterized in that: The base layer welding current is 140-160A, the arc voltage is 18-22V, the welding speed is 20-30cm / min, the shielding gas flow rate is 16-18L / min, and the interlayer temperature does not exceed 200°C.

3. The process for producing the wear-resistant dredging pipe according to claim 1, characterized in that: The welding current of the filling layer welding is 160-180A, the arc voltage is 20-25V, the welding speed is 30-40cm / min, the shielding gas flow rate is 16-20L / min, and the interlayer temperature does not exceed 200°C.

4. The process for producing a wear-resistant dredging pipe according to claim 1, characterized in that: The welding current of the cover layer welding is 150-200A, the arc voltage is 20-25V, the welding speed is 30-40cm / min, the protective gas flow rate is 16-20L / min, and the interlayer temperature does not exceed 200℃.

5. The process for producing the wear-resistant dredging pipe according to claim 1, characterized in that: The raw materials for preparing the wear-resistant steel plate include: C, Si, Mn, P, S, Cu, Ni, Cr, Nb, Al, Ti, Mo, B, N, and Fe.

6. The process for producing a wear-resistant dredging pipe according to claim 1, characterized in that: The M7 rolling steps include: L1, continuous casting billet heating; L2, descaling; L3, rough rolling; L4, finishing rolling; L5, hot straightening; L6, steel plate marking; L7, cooling bed; L8, shearing; L9, marking; L10, quenching and tempering; L11, stacking and warehousing.

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