Hastelloy welding strip and electroslag welding flux for surfacing of inner wall of crushed coal pressurized gasification furnace, and preparation method and welding method of Hastelloy welding strip and electroslag welding flux

Abstract

The invention discloses a hastelloy welding strip for overlaying of the inner wall of a crushed coal pressurized gasification furnace, an electroslag welding flux, a preparation method and a welding method, and belongs to the field of welding materials. The problem of corrosion of surfacing metal after surfacing of the inner wall of the existing crushed coal pressurized gasification furnace is solved. By regulating and controlling the element content in the hastelloy welding strip and the electroslag welding flux, the situation that Fe and Si in surfacing metal exceed the standard is avoided, the oxygen content and high-temperature burning loss of the surfacing metal are reduced, meanwhile, the thermite is added into the electroslag welding flux, the granularity range of the electroslag welding flux is appropriate, the stability of the welding process is improved, the welding manufacturability is improved, and the welding quality is improved. When the Hastelloy welding strip and the electroslag welding flux are used for surfacing, surfacing metal components meet the requirements of Hastelloy NiCrMo-10 in the coil II C sheet SFA5.39 in ASME specifications, the welding manufacturability is good, the crack resistance and corrosion resistance of surfacing metal are good, and the use requirements of the crushed coal pressurized gasification furnace are met.

Description

Technical Field

[0001] The invention belongs to the field of welding materials, and particularly relates to a Hastelloy welding strip and an electroslag welding flux for surfacing the inner wall of a crushed coal pressurized gasifier, and a preparation method and a welding method. Background Art

[0002] With the rapid development of the world economy, the demand for energy is also growing. Coal, as an energy source, occupies an important position in the economy. How to utilize this special energy and maximize the efficiency of coal use has become an important part of energy technology research.

[0003] Crushed coal pressurized gasification technology is a new type of coal utilization technology. It refers to the use of crushed coal as raw material in a high-temperature and high-pressure pressurized gasifier, which is pressurized to high temperature and high pressure conditions to decompose it into gas, which flows into subsequent equipment to prepare various gases, fuel oils, liquids, etc. This technology can not only utilize low-grade coal in large quantities, but also effectively increase energy conversion efficiency. It can effectively convert low-grade coal into higher-value products and is an effective energy utilization technology.

[0004] The most widely used crushed coal pressurized gasifier at present is the Lurgi furnace. The Lurgi furnace is made of carbon steel and uses granular coal for feeding. It can use all types of coal except coking coal. The coal is added to the gasifier through a lock bucket, and the ash is discharged out of the furnace through an ash lock bucket. However, there are problems of corrosion of the inner wall of the gasifier and thinning of the furnace wall. The corrosion of the inner wall of the gasifier is mainly caused by high-temperature sulfide corrosion, which can be repaired by cladding NiCrMo-3 alloy on the inner wall. However, the traditional NiCrMo-3 alloy has a low content of corrosion-resistant metal elements and poor synergy of various components. When the temperature of the gasifier reaches 1000°C, the cladding metal on the inner wall will still gradually corrode.

[0005] Hastelloy is a nickel-based corrosion-resistant alloy that is used in agricultural chemicals, energy industry, nuclear facilities, biopharmaceuticals and other fields, but it has not been widely discussed in terms of welding with welding strips, and has the potential for further research. Therefore, it is necessary to further study the application of Hastelloy in welding strips, and at the same time develop a Hastelloy welding strip and its matching electroslag flux, so that the surfacing metal of the inner wall of the crushed coal pressurized gasifier has good corrosion resistance after surfacing, thereby avoiding corrosion of the inner wall of the gasifier. Summary of the invention

[0006] In order to solve the corrosion problem of cladding metal after cladding welding of the inner wall of the existing crushed coal pressurized gasifier, the present invention provides a Hastelloy welding strip, an electroslag welding flux, a preparation method and a welding method for cladding the inner wall of the crushed coal pressurized gasifier.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] One of the purposes of the present invention is to provide a Hastelloy alloy welding strip for surfacing welding the inner wall of a crushed coal pressurized gasifier. The chemical composition of the Hastelloy alloy welding strip, measured by weight percentage, includes: C: ≤0.010%, Si: ≤0.05%, Mn: ≤0.50%, S: ≤0.003%, P: ≤0.010%, Cr: 20.0-22.5%, Mo: 12.5-14.5%, Cu: ≤0.20%, Fe: 0.1-1.0%, Co: ≤2.5%, W: 2.5-3.5%, V: ≤0.08%, Al: 0.05-0.30%, Nb: ≤0.05%, Ti: ≤0.10%, and the balance is Ni.

[0009] The second object of the present invention is to provide a method for preparing a Hastelloy alloy welding strip for surfacing welding the inner wall of a crushed coal pressurized gasifier, the method comprising: weighing each component in proportion, undergoing a double melting, forging, hot rolling, and shearing process combining vacuum induction melting and electroslag remelting, to obtain a finished Hastelloy alloy welding strip with a specification of 0.5×60mm.

[0010] It is further defined that the vacuum induction melting process parameters are: molten steel refining temperature 1550~1570℃, and steel tapping temperature 1480~1510℃.

[0011] It is further defined that the forging process parameters are: initial forging temperature 1120-1150°C, final forging temperature 870°C, and forging blank specification 60×200mm.

[0012] It is further defined that the hot rolling process parameters are: initial rolling temperature 1120~2000℃, final rolling temperature 890℃, steel strip specification after hot rolling 3.2×210mm, and cooling method is air cooling.

[0013] The third object of the present invention is to provide an electroslag flux for use with the Hastelloy welding strip for surfacing welding the inner wall of the above-mentioned crushed coal pressurized gasifier, wherein the chemical composition of the electroslag flux, by weight percentage, includes: calcium fluoride: 50-75%, aluminum oxide: 10-25%, iron powder: 1-3%, aluminum powder 0.2-1%, magnesium oxide: 5-15%, sodium fluoride: 1-3%, metallic chromium: 1-3%, molybdenum powder: 1-2%, and tungsten powder: 0.5-1%.

[0014] It is further defined that the iron powder and the aluminum powder constitute the thermite.

[0015] The fourth object of the present invention is to provide a method for preparing the electroslag flux for surfacing welding the inner wall of the above-mentioned crushed coal pressurized gasification furnace, the method comprising: weighing each component in proportion, dry mixing evenly, adding water glass, wet mixing evenly and then granulating, after granulation is completed, first low-temperature drying, then high-temperature baking, screening, to obtain the electroslag flux.

[0016] It is further defined that the amount of water glass added is 8-10% by weight of the electroslag welding flux.

[0017] It is further defined that the low-temperature drying temperature is 200°C and the high-temperature baking temperature is 400°C.

[0018] It is further defined that the particle size of the electroslag welding flux is 30 to 40 meshes.

[0019] The fifth object of the present invention is to provide a method for surfacing welding the inner wall of a crushed coal pressurized gasifier. The Hastelloy welding strip and electroslag flux used in the welding method are as described above. The welding method parameters are: welding current 850~950A, welding voltage 25.5~26.5V, welding speed 180~200mm / min, magnetron current 1.0~2.0A, and interpass temperature 50~150℃.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention provides a Hastelloy welding strip and an electroslag flux, which are used for surfacing welding of the inner wall of a crushed coal pressurized gasifier. After surfacing welding, the surfacing metal composition meets the requirements of ASME (American Society of Mechanical Engineers) Code Volume II, Part C SFA5.39 on Hastelloy NiCrMo-10. Meeting this requirement does not reduce the performance and corrosion resistance of the surfacing metal in the high-temperature ring use environment of the inner wall of the crushed coal pressurized gasifier, and is better than the traditional NiCrMo-3. In addition, the welding strip and flux provided by the present invention are used for welding, and the welding processability, crack resistance and corrosion performance of the surfacing metal are good, which meets the use requirements of the gasifier, solves the problem of corrosion of the surfacing metal after surfacing welding of the inner wall of the crushed coal pressurized gasifier, and thus can avoid corrosion of the inner wall of the gasifier. Compared with the prior art, the present application also has the following beneficial effects:

[0022] (1) The welding strip provided by the present invention is a Hastelloy welding strip, wherein the Fe content is 0.1-1.0%. After surfacing with the electroslag welding flux, the Fe content in the surfacing metal is in the range of 2-6%, which meets the requirements of ASME specification Volume II, Part C SFA5.39 on Hastelloy NiCrMo-10, and avoids the excessive Fe content in the surfacing metal on the carbon steel base material (the specification requires 2-6%). At the same time, by strictly controlling the C, Si, S, and P element contents in the welding strip, the crack resistance and corrosion performance of the surfacing metal are improved. In addition, by controlling the Al element content in the welding strip to 0.05%-0.30%, the oxygen content of the surfacing metal is reduced, the redox relationship of the surfacing metal is adjusted, and the high-temperature burning of the surfacing metal is reduced, thereby preventing the surfacing metal from being corroded after surfacing welding on the inner wall of the crushed coal pressurized gasifier.

[0023] (2) The electroslag flux provided by the present invention is prepared from high-purity powder, which reduces the content of C, Si, S and P elements brought into the cladding alloy due to impure powder, thereby improving the corrosion resistance of the cladding metal. At the same time, the flux provided by the present invention has a suitable particle size range, which makes the flux easier to start an arc and quickly enter the electroslag cladding process, thereby improving the stability of the welding process, reducing the spatter during the welding process, and preventing slag inclusions from being generated at the overlap, which is also beneficial to improving the corrosion resistance of the cladding metal on the inner wall of the gasifier in the later stage.

[0024] (3) The electroslag flux provided by the present invention contains thermite (composed of iron powder and aluminum powder), which provides sufficient heat required in the electroslag cladding welding process and reduces the welding current, thereby avoiding the magnetic blow problem caused by high current when welding Hastelloy alloy and improving the welding processability.

[0025] (4) The present invention bakes the electroslag flux at a temperature between that of the bonding flux and the sintering flux, thereby reducing the loss of alloy due to high-temperature oxidation during the flux manufacturing process and improving the alloy utilization rate. In addition, the amount of water glass added to the electroslag flux is relatively small (8-10%), and the redox relationship of the cladding metal has been adjusted by regulating the Al content in the Hastelloy welding strip, thereby solving the problem that the Si content in the metal cannot be ≤0.20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The processability of the cladding metal welded using the Hastelloy welding strip and electroslag welding flux of Example 1;

[0027] Figure 2 The processability of the cladding metal welded using the Hastelloy welding strip and electroslag welding flux of Example 2;

[0028] Figure 3 The processability of the cladding metal welded using the Hastelloy welding strip and electroslag welding flux of Example 3;

[0029] Figure 4 This is an intergranular corrosion sample diagram of a sample welded using the Hastelloy welding strip and electroslag welding flux of Example 1;

[0030] Figure 5 This is an intergranular corrosion sample diagram of a sample welded using the Hastelloy welding strip and electroslag welding flux of Example 2;

[0031] Figure 6 This is a graph of intergranular corrosion of the sample welded using the Hastelloy welding strip and electroslag flux of Example 3. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0034] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained through commercial channels by those skilled in the art.

[0035] Example 1

[0036] The chemical composition of the Hastelloy welding strip of this embodiment, measured by weight percentage, includes: C: 0.005%, Si: 0.05%, Mn: 0.25%, S: 0.001%, P: 0.002%, Cr: 21.52%, Mo: 12.83%, Cu: 0.010%, Fe: 0.53%, Co: 0.05%, W: 2.97%, V: 0.001%, Al: 0.28%, Nb: 0.03%, Ti: 0.03%, and the balance is Ni. The specific composition is shown in Table 1.

[0037] The preparation method of the Hastelloy alloy welding strip is as follows: weighing each component in proportion, and subjecting the components to vacuum induction melting + electroslag remelting (VIM + ESR), forging, hot rolling, and shearing processes, to finally obtain a Hastelloy alloy welding strip with a specification of 0.5×60 mm;

[0038] In the VIM+ESR process, the initial additives for vacuum induction melting include electrolytic nickel (Ni≥99.5%), metallic chromium (Cr≥99.9%), molybdenum bars (Mo≥99.9%), tungsten bars (W≥99.9%), aluminum (Al≥99.9%), and pure iron (Fe≥99.8%). The molten steel refining temperature is 1550-1570°C, and the tapping temperature is 1480-1510°C.

[0039] In the forging process, the forging billet specification is 60×200mm, and it is divided into four continuous temperature intervals for forging according to the temperature of the crushed coal pressurized gasifier when in use. The temperatures of the four zones are 780℃, 900℃, 1050℃, and 1150℃ respectively. Each temperature is maintained for 30 minutes. When the holding time is up, it enters the next temperature interval. Overall, the four temperature intervals form a continuous state for forging. The initial forging temperature is 1120℃ and the final forging temperature is 870℃.

[0040] In the hot rolling process, the steel strip specification after hot rolling is 3.2×210mm. It is hot rolled in four continuous temperature intervals according to the temperature of the crushed coal pressurized gasifier. The four temperatures are 890℃, 1000℃, 1120℃ and 1200℃ respectively. The rolling process of the four areas is continuous, that is, the welding strip is continuously moving. The starting rolling temperature is 1120℃, the final rolling temperature is 890℃, and the cooling method is air cooling.

[0041] During the shearing process, the steel coil specifications are 0.5×190mm and the finished product specifications are 0.5×60mm.

[0042] The chemical composition of the electroslag welding flux of the present embodiment, measured by weight percentage, includes: calcium fluoride: 55%, aluminum oxide: 25%, iron powder: 1.3%, aluminum powder: 0.4%, magnesium oxide: 13.5%, sodium fluoride: 1.3%, metallic chromium: 1.3%, molybdenum powder: 1.6%, tungsten powder: 0.6%, wherein iron powder and aluminum powder are components used to form thermite, that is, thermite is introduced into the electroslag welding flux of the present embodiment. The specific composition of the welding flux is shown in Table 2.

[0043] The purity of each component in the flux is: calcium fluoride (CaF 2 ≥97%), alumina (Al 2 O 3 ≥99%), iron powder (Fe≥99.5%), aluminum powder (Al≥99.5%), magnesium oxide (MgO≥98%), sodium fluoride (NaF≥98%), metallic chromium (Cr≥99.8%), molybdenum powder (Mo≥99.8%), and tungsten powder (W≥99.8%).

[0044] The preparation method of the above-mentioned electroslag flux is as follows: weigh each component in proportion and mix them evenly, add 8-10% of the total mass of the electroslag flux formula of water glass (potassium-sodium ratio is 1:1) as a binder for wet stirring, granulate after mixing evenly, and after granulation, first dry it at 200°C, then bake it at 400°C (this temperature is between the bonding and sintering fluxes), sieve it, and obtain the flux. The particle size of the finished flux is controlled at 30-40 meshes.

[0045] According to the process parameters in Table 4, electroslag surfacing was performed on the Q235R steel plate. The size of the steel plate was 300mm×300mm×40mm. Two layers were surfacing on the steel plate. The total thickness of the two layers was 6-7mm. The processability was shown in Figure 1 As shown, the welding process is stable, spatter is small, overlap fusion is good, slag is easy to remove, weld bead corrugation is fine, and the overall processability is good.

[0046] The composition of the cladding metal was tested within 2 mm below the surface of the cladding metal. The chemical composition is shown in Table 3. It can be seen that the chemical composition of the cladding metal in this embodiment meets the requirements of Hastelloy NiCrMo-10 in SFA5.39, Part C, Volume II of the ASME Code. The performance test of the test plate was carried out, and the intergranular corrosion test was carried out according to the ASTM G28 A method. Figure 4 , the test results are shown in Table 5.

[0047] Example 2

[0048] The chemical composition of the Hastelloy welding strip of this embodiment, measured by weight percentage, includes: C: 0.004%, Si: 0.02%, Mn: 0.23%, S: 0.001%, P: 0.002%, Cr: 21.98%, Mo: 13.25%, Cu: 0.006%, Fe: 0.73%, Co: 0.06%, W: 3.01%, V: 0.001%, Al: 0.15%, Nb: 0.02%, Ti: 0.02%, and the balance is Ni. The specific composition is shown in Table 1.

[0049] The preparation method of the Hastelloy alloy welding strip is as follows: weighing each component in proportion, and subjecting the components to vacuum induction melting + electroslag remelting (VIM + ESR), forging, hot rolling, and shearing processes, to finally obtain a Hastelloy alloy welding strip with a specification of 0.5×60 mm;

[0050] In the VIM+ESR process, the initial additives for vacuum induction melting include electrolytic nickel, metallic chromium, molybdenum bars, tungsten bars, aluminum, and pure iron. The molten steel refining temperature is 1550-1570°C, and the tapping temperature is 1480-1510°C.

[0051] In the forging process, the forging billet specification is 60×200mm, and it is divided into four continuous temperature intervals for forging according to the temperature of the crushed coal pressurized gasifier when in use. The temperatures of the four zones are 780℃, 900℃, 1050℃, and 1150℃ respectively. Each temperature is maintained for 30 minutes. When the holding time is up, it enters the next temperature interval. Overall, the four temperature intervals form a continuous state for forging. The initial forging temperature is 1120℃ and the final forging temperature is 870℃.

[0052] In the hot rolling process, the steel strip specification after hot rolling is 3.2×210mm. It is hot rolled in four continuous temperature intervals according to the temperature of the crushed coal pressurized gasifier. The four temperatures are 890℃, 1000℃, 1120℃ and 1200℃ respectively. The rolling process of the four areas is continuous, that is, the welding strip is continuously moving. The starting rolling temperature is 1120℃, the final rolling temperature is 890℃, and the cooling method is air cooling.

[0053] During the shearing process, the steel coil specifications are 0.5×190mm and the finished product specifications are 0.5×60mm.

[0054] The chemical composition of the electroslag welding flux of the present embodiment, measured by weight percentage, includes: calcium fluoride: 62%, aluminum oxide: 20%, iron powder: 1.9%, aluminum powder: 0.6%, magnesium oxide: 9.4%, sodium fluoride: 2%, metallic chromium: 1.8%, molybdenum powder: 1.5%, tungsten powder: 0.8%, wherein iron powder and aluminum powder are components used to form thermite, that is, thermite is introduced into the electroslag welding flux of the present embodiment. The specific composition of the welding flux is shown in Table 2, and the purity of the raw materials of each component is the same as that of Example 1.

[0055] The preparation method of the above-mentioned electroslag flux is as follows: weigh each component in proportion and mix them evenly, add 8-10% water glass (potassium-sodium ratio is 1:1) as a binder to the total mass of the electroslag flux formula and wet stir, granulate after mixing evenly, and after granulation, first dry it at 200°C, then bake it at 400°C (this temperature is between bonding and sintering flux), sieve it, and obtain the flux, and the particle size of the finished flux is controlled at 30-40 meshes.

[0056] According to the process parameters in Table 4, electroslag surfacing welding is performed on the Q235R steel plate. The size of the steel plate is 300mm×300mm×40mm. Two layers are surfacing welded on the steel plate. The total surfacing thickness of the layers is 6-7mm. The processability is shown in Figure 2 As shown, the welding process is stable, spatter is small, overlap fusion is good, slag is easy to remove, weld bead corrugation is fine, and the overall processability is good.

[0057] The composition of the cladding metal was tested within 2 mm below the surface of the cladding metal. The chemical composition is shown in Table 3. It can be seen that the chemical composition of the cladding metal in this embodiment meets the requirements of Hastelloy NiCrMo-10 in SFA5.39, Part C, Volume II of the ASME Code. The performance test of the test plate was carried out, and the intergranular corrosion test was carried out according to the ASTM G28 A method. Figure 5 , the test results are shown in Table 5.

[0058] Example 3

[0059] The chemical composition of the Hastelloy welding strip of this embodiment, measured by weight percentage, includes: C: 0.005%, Si: 0.03%, Mn: 0.21%, S: 0.001%, P: 0.002%, Cr: 22.2%, Mo: 13.35%, Cu: 0.008%, Fe: 0.85%, Co: 0.05%, W: 3.03%, V: 0.001%, Al: 0.08%, Nb: 0.03%, Ti: 0.04%, and the balance is Ni. The specific composition is shown in Table 1.

[0060] The preparation method of the Hastelloy alloy welding strip is as follows: weighing each component in proportion, and subjecting the components to vacuum induction melting + electroslag remelting (VIM + ESR), forging, hot rolling, and shearing processes, to finally obtain a Hastelloy alloy welding strip with a specification of 0.5×60 mm;

[0061] In the VIM+ESR process, the initial additives for vacuum induction melting include electrolytic nickel, metallic chromium, molybdenum bars, tungsten bars, aluminum, and pure iron. The molten steel refining temperature is 1550-1570°C, and the tapping temperature is 1480-1510°C.

[0062] In the forging process, the forging billet specification is 60×200mm, and it is divided into four continuous temperature intervals for forging according to the temperature of the crushed coal pressurized gasifier when in use. The temperatures of the four zones are 780℃, 900℃, 1050℃, and 1150℃ respectively. Each temperature is maintained for 30 minutes. When the holding time is up, it enters the next temperature interval. Overall, the four temperature intervals form a continuous state for forging. The initial forging temperature is 1120℃ and the final forging temperature is 870℃.

[0063] In the hot rolling process, the steel strip specification after hot rolling is 3.2×210mm. It is hot rolled in four continuous temperature intervals according to the temperature of the crushed coal pressurized gasifier. The four temperatures are 890℃, 1000℃, 1120℃ and 1200℃ respectively. The rolling process of the four areas is continuous, that is, the welding strip is continuously moving. The starting rolling temperature is 1120℃, the final rolling temperature is 890℃, and the cooling method is air cooling.

[0064] During the shearing process, the steel coil specifications are 0.5×190mm and the finished product specifications are 0.5×60mm.

[0065] The chemical composition of the electroslag welding flux of the present embodiment, measured by weight percentage, includes: calcium fluoride: 73%, aluminum oxide: 11.4%, iron powder: 2.5%, aluminum powder: 0.8%, magnesium oxide: 5.0%, sodium fluoride: 2.7%, metallic chromium: 2.6%, molybdenum powder: 1.3%, tungsten powder: 0.7%, wherein iron powder and aluminum powder are components used to form thermite, that is, thermite is introduced into the electroslag welding flux of the present embodiment. The specific composition of the welding flux is shown in Table 2, and the purity of the raw materials of each component is the same as that of Example 1.

[0066] The preparation method of the above-mentioned electroslag flux is as follows: weigh each component in proportion and mix them evenly, add 8%-10% water glass (potassium-sodium ratio is 1:1) of the total mass of the electroslag flux formula as a binder for wet stirring, granulate after mixing evenly, and after granulation, first dry it at 200°C, then bake it at 400°C (this temperature is between the bonding and sintering fluxes), sieve it, and obtain the flux. The particle size of the finished flux is controlled at 30-40 meshes.

[0067] According to the process parameters in Table 4, electroslag surfacing was performed on the Q235R steel plate. The size of the steel plate was 300mm×300mm×40mm. Two layers were surfacing on the steel plate. The total thickness of the two layers was 6-7mm. The processability was shown in Figure 3 As shown, the welding process is stable, spatter is small, overlap fusion is good, slag is easy to remove, weld bead corrugation is fine, and the overall processability is good.

[0068] The composition of the cladding metal was tested within 2 mm below the surface of the cladding metal. The chemical composition is shown in Table 3. It can be seen that the chemical composition of the cladding metal in this embodiment meets the requirements of Hastelloy NiCrMo-10 in SFA5.39, Part C, Volume II of the ASME Code. The performance test of the test plate was carried out, and the intergranular corrosion test was carried out according to the ASTM G28 A method. Figure 6 , the test results are shown in Table 5.

[0069] Table 1 Chemical composition of Hastelloy alloy welding strips in Examples 1 to 3 (mass percentage, %)

[0070]

[0071]

[0072] Table 2 Example 1-3 Electroslag welding flux formula (mass percentage, %)

[0073] raw materials Example 1 Example 2 Example 3 Calcium Fluoride 55 62 73 Alumina 25 20 11.4 Iron Fan 1.3 1.9 2.5 Aluminum powder 0.4 0.6 0.8 Magnesium Oxide 13.5 9.4 5.0 Sodium fluoride 1.3 2 2.7 Chromium 1.3 1.8 2.6 Molybdenum powder 1.6 1.5 1.3 Tungsten powder 0.6 0.8 0.7

[0074] Table 3 Chemical composition of the cladding metals prepared in Examples 1 to 3 and the values ​​required by ASME SFA 5.9 (mass percentage, %)

[0075]

[0076]

[0077] Table 4 Welding process parameters of Examples 1 to 3

[0078]

[0079] Table 5 Performance results of surfacing metals in Examples 1 to 3

[0080]

[0081] From Table 5 and Figures 4 to 6 It can be seen that the samples of Examples 1 to 3 have good side bending performance, no cracks in the side bending, and the intergranular corrosion rates are 0.48mm / a, 0.43mm / a, and 0.35mm / a, respectively, all lower than 0.5mm / a, indicating that the surfacing metal after surfacing welding with the Hastelloy alloy welding strip prepared by the present invention and the electroslag welding flux has excellent crack resistance and corrosion resistance, so that the samples also have good crack resistance and corrosion resistance, and can meet the engineering requirements of the crushed coal pressurized gasifier.

[0082] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A Hastelloy alloy welding strip for surfacing welding the inner wall of a crushed coal pressurized gasifier, characterized in that: The chemical composition, by weight percentage, includes: C: ≤0.010%, Si: ≤0.05%, Mn: ≤0.50%, S: ≤0.003%, P: ≤0.010%, Cr: 20.0~22.5%, Mo: 12.5~14.5%, Cu: ≤0.20%, Fe: 0.1~1.0%, Co: ≤2.5%, W: 2.5~3.5%, V: ≤0.08%, Al: 0.05~0.30%, Nb: ≤0.05%, Ti: ≤0.10%, and the balance is Ni.

2. A method for preparing the Hastelloy welding strip according to claim 1, characterized in that: The method comprises: weighing each component in proportion, and performing double melting, forging, hot rolling and shearing processes combining vacuum induction melting and electroslag remelting to obtain a Hastelloy welding strip product with a specification of 0.5×60mm.

3. The preparation method according to claim 2, characterized in that: The parameters of vacuum induction melting process are: molten steel refining temperature 1550~1570℃, steel tapping temperature 1480~1510℃.

4. The preparation method according to claim 2, characterized in that: The forging process parameters are: initial forging temperature 1120-1150°C, final forging temperature 870°C, forging blank specification 60×200mm; The hot rolling process parameters are: initial rolling temperature 1120~2000℃, final rolling temperature 890℃, steel strip specification after hot rolling is 3.2×210mm, and cooling method is air cooling.

5. An electroslag welding flux for surfacing welding the inner wall of a crushed coal pressurized gasifier, characterized in that: The electroslag welding flux is used in conjunction with the Hastelloy welding strip according to claim 1. The chemical composition of the electroslag welding flux, measured by weight percentage, includes: calcium fluoride: 50-75%, aluminum oxide: 10-25%, iron powder: 1-3%, aluminum powder 0.2-1%, magnesium oxide: 5-15%, sodium fluoride: 1-3%, metallic chromium: 1-3%, molybdenum powder: 1-2%, and tungsten powder: 0.5-1%; The iron powder and the aluminum powder constitute thermite.

6. A method for preparing a flux used in conjunction with a Hastelloy welding strip as claimed in claim 5, characterized in that: The method comprises: weighing each component in proportion, dry-mixing evenly, adding water glass, wet-mixing evenly and then granulating, and after granulation, first drying at low temperature, then baking at high temperature, and screening to obtain the electroslag welding flux.

7. The preparation method according to claim 6, characterized in that: The amount of water glass added is 8-10% of the weight of the electroslag flux.

8. The preparation method according to claim 6, characterized in that: The low temperature drying temperature is 200℃ and the high temperature baking temperature is 400℃.

9. The preparation method according to claim 6, characterized in that: The particle size of electroslag welding flux is 30-40 mesh.

10. A method for surfacing welding the inner wall of a crushed coal pressurized gasifier, characterized in that: The welding method uses the Hastelloy welding strip described in claim 1 and the electroslag welding flux described in claim 5, and the welding method parameters are: welding current 850-950A, welding voltage 25.5-26.5V, welding speed 180-200mm / min, magnetron current 1.0-2.0A, and interpass temperature 50-150°C.

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