Cobalt-base-containing material, welding wire based on cobalt-base-containing material and preparation method

Abstract

The invention discloses a cobalt-based material which is prepared from the following components in percentage by mass: 50.0%-60.0% of Cr, 5.0%-8.0% of Ni, 6.0%-8.0% of C, 8.0%-10.0% of Mo, 2.0%-4.0% of W, 0.5%-0.8% of Mn, 2.5%-3.5% of Si and the balance of Fe, and the sum of the mass percentages of the components is 100%. The invention further discloses a preparation method of the cobalt-based material. The preparation method comprises the following steps: weighing the cobalt-based material, drying and mixing; the invention further discloses a welding wire based on the cobalt-base-containing material. The cobalt-base-containing material is wrapped by the welding skin. The preparation method comprises the following steps: removing grease from alcohol, wrapping the cobalt-based material to obtain a core roll, putting the core roll into a drawing mold, and drawing to obtain the welding wire based on the cobalt-based material; the problem that in the prior art, a water cooling wall tube material is poor in high-temperature corrosion resistance, and safety accidents are prone to occurring is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal materials, and specifically relates to a cobalt-containing base material. The present invention also relates to a method for preparing the cobalt-containing base material. The present invention also relates to a welding wire based on the material and a method for preparing the welding wire. Background Art

[0002] Boilers are an important part of the generator set of coal-fired power plants. The heating surface of the boiler should be able to withstand high temperature and high pressure, and have good corrosion resistance and wear resistance. The boiler economizer, water-cooled wall tubes, reheater tubes and superheater tubes (referred to as "four tubes") are the main components of the heating surface in the boiler structure system. If there are problems with the welding quality of the boiler's "four tubes", accidents such as explosions and leaks will occur. Therefore, it is required that in the actual operation and development of thermal power plants, the safety inspection of the boiler's "four tubes" should be emphasized in combination with the actual situation, the causes of the failures should be deeply analyzed, and targeted leakage prevention measures should be formulated to improve the safety of boiler operation in thermal power plants. Among the "four tubes" of the boiler, the water-cooled wall tubes have the most accidents. The failure of the water-cooled wall tubes is mainly caused by corrosion and wear. Related studies have shown that there is a regularity when the water-cooled wall tubes generate high temperatures, and most of them are located in the burner supply area and the area with high heat load. The wear of the water-cooled wall tubes is mostly around the nozzle of the short soot blower in the furnace. In actual boilers, due to the complex composition of flue gas in the furnace and the intensification of deep peak-shaving tasks in recent years, high-temperature corrosion and wear of the water-cooled wall tubes occur simultaneously. The simultaneous existence of the two aggravates the thinning of the tube wall and leads to leakage and tube burst accidents.

[0003] The water-cooled wall tubes are arranged in a large area in the furnace. Conventional water-cooled wall tubes are made of pearlite heat-resistant steel, such as 12Cr1MoV and 15CrMo, which have poor resistance to high-temperature flue gas corrosion and wear. If the boiler water-cooled wall tubes are replaced with nickel-based or cobalt-based materials with excellent high-temperature corrosion resistance, the corrosion and wear resistance of the tube wall can be significantly improved, but the cost is high. Preparing a high-temperature abrasion-resistant cladding layer on the surface of the water-cooled wall tube can not only significantly improve the high-temperature abrasion resistance of the water-cooled wall tube, but also reduce costs. It is an ideal choice for improving the safe service of the water-cooled wall tube. Summary of the invention

[0004] The purpose of the present invention is to provide a cobalt-based material, which solves the problem in the prior art that the material used to prepare the water-cooled wall tube has poor high temperature resistance and corrosion resistance.

[0005] The second object of the present invention is to provide a method for preparing a cobalt-containing base material.

[0006] The third object of the present invention is to provide a welding wire based on a cobalt-containing material, which solves the problem in the prior art that the water-cooled wall tube material has poor high-temperature corrosion resistance and is prone to safety accidents.

[0007] A fourth object of the present invention is to provide a method for preparing a welding wire based on a cobalt-containing base material.

[0008] The first technical means adopted by the present invention is that the cobalt-containing base material is composed of the following components in mass percentage: 50.0~60.0% Cr, 5.0~8.0% Ni, 6.0~8.0% C, 8.0~10.0% Mo, 2.0~4.0% W, 0.5~0.8% Mn, 2.5~3.5% Si, and the rest is Fe, and the sum of the mass percentages of the above components is 100%.

[0009] The present invention is also characterized in that: The particle sizes of Cr, Ni, Mo, W, Mn and Fe are all 100~200 mesh.

[0010] The second technical solution adopted by the present invention is a method for preparing a cobalt-based material, and the specific steps are as follows: Step 1. Weigh the following components according to mass percentage: 50.0-60.0% Cr, 5.0-8.0% Ni, 6.0-8.0% C, 8.0-10.0% Mo, 2.0-4.0% W, 0.5-0.8% Mn, 2.5-3.5% Si, and the rest is Fe. The sum of the mass percentages of the above components is 100%.

[0011] Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring to obtain a cobalt-containing material.

[0012] The second technical solution of the present invention is also characterized in that: The heating temperature is 200~260℃, the heating time is 1~3h, the stirring time is 1~3h, and the stirring rate is 60~90r / min.

[0013] The third technical solution adopted by the present invention is that the welding wire based on the cobalt-containing base material includes a welding skin, and the welding skin is wrapped with the cobalt-containing base material.

[0014] The fourth technical solution adopted by the present invention is a method for preparing a welding wire based on a cobalt-based material, and the specific steps are as follows: Step 1, remove the grease on the surface of the CoCr20W15Ni strip with alcohol to obtain the outer skin; Step 2, wrapping the outer skin with a cobalt-based material to obtain a core roll; Step 3: Place the core coil into a drawing die for drawing to obtain a welding wire based on a cobalt-containing material.

[0015] The fourth technical solution of the present invention is also characterized in that: The drawing die has multiple apertures ranging from 2.6 to 1.0 mm, and the apertures in the drawing die are arranged in order from large to small.

[0016] The filling rate of cobalt-based materials in welding wire based on cobalt-based materials is 20~22%.

[0017] The diameter of the welding wire based on cobalt-containing base materials is 1.0~1.2mm.

[0018] The beneficial effects of the present invention are: The high temperature abrasion resistant cobalt-based welding wire for water-cooled wall tubes of the present invention is suitable for surfacing welding of the heating surface of the water-cooled wall in thermal power plants, and can shorten the service life of the heating surface of the water-cooled wall under severe working conditions of deep peak regulation.

[0019] The main alloy system is Co-Cr-WC alloy system, which is mainly composed of α-Co, ε-Co, Co3Mo2Si and W2C. The cobalt-based solid solution has good plasticity and toughness, and excellent high temperature resistance; with the addition of Mo, Si, C and W elements, the in-situ generated Co3Mo2Si Laves phase and W2C carbide are dispersed on the cobalt matrix, which can effectively improve the hardness of the cladding layer and has excellent wear resistance.

[0020] The Co3Mo2Si Laves phase and W2C carbide jointly improve the wear resistance of the cladding layer. Due to the different crystal structures and properties of the two, multiple hard phases are generated in situ in the cladding layer, which has a better effect than a single hard phase. The hard phases also promote each other, thereby jointly improving the wear resistance of the cobalt matrix.

[0021] The TIG and MIG / MAG processes are used for surfacing welding, which can be used for surfacing protection of water-cooled wall surfaces as well as for other structural parts that require high-temperature abrasion protection. The welding wire has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an electron microscope image of the cross-section metallographic structure of the welding wire prepared in Example 2; Figure 2 This is an enlarged electron microscope image of the cross-section of the welding wire prepared in Example 2; Figure 3 This is an electron microscope image of the morphology of the welding wire prepared in Example 2 after high-temperature etching. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The cobalt-containing base material of the present invention is composed of the following components in mass percentage: 50.0-60.0% of Cr, 5.0-8.0% of Ni, 6.0-8.0% of C, 8.0-10.0% of Mo, 2.0-4.0% of W, 0.5-0.8% of Mn, 2.5-3.5% of Si, and the rest is Fe, and the sum of the mass percentages of the above components is 100%.

[0025] The particle sizes of Cr, Ni, Mo, W, Mn and Fe are all 100~200 mesh.

[0026] The method for preparing the cobalt-containing base material of the present invention comprises the following specific steps: Step 1. Weigh the following components according to mass percentage: 50.0-60.0% Cr, 5.0-8.0% Ni, 6.0-8.0% C, 8.0-10.0% Mo, 2.0-4.0% W, 0.5-0.8% Mn, 2.5-3.5% Si, and the rest is Fe. The sum of the mass percentages of the above components is 100%.

[0027] Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring to obtain a cobalt-containing material.

[0028] The heating temperature is 200~260℃, the heating time is 1~3h, the stirring time is 1~3h, and the stirring rate is 60~90r / min.

[0029] The welding wire based on the cobalt-containing base material of the present invention comprises a welding skin, wherein the welding skin is coated with the cobalt-containing base material.

[0030] The method for preparing the welding wire based on the cobalt-containing material of the present invention comprises the following specific steps: Step 1, remove the grease on the surface of the CoCr20W15Ni strip with alcohol to obtain the outer skin; Step 2, wrapping the outer skin with a cobalt-based material to obtain a core roll; Step 3: Place the core coil into a drawing die for drawing to obtain a welding wire based on a cobalt-containing material.

[0031] The drawing die has multiple apertures ranging from 2.6 to 1.0 mm, and the apertures in the drawing die are arranged in order from large to small.

[0032] The filling rate of cobalt-based materials in welding wire based on cobalt-based materials is 20~22%.

[0033] The diameter of the welding wire based on cobalt-containing base materials is 1.0~1.2mm.

[0034] The main element in the welding wire is Co: Co-based alloys have excellent wear resistance, high temperature oxidation resistance and corrosion resistance. The Co-Cr-WC alloy system used in the present invention comprehensively improves the comprehensive performance of the cladding layer by carbide precipitation strengthening and alloy element solid solution strengthening.

[0035] Cr element in welding wire: Cr contained in cobalt-based alloy can ensure that the alloy has excellent high temperature resistance. Cr reacts with O at high temperature to form dense Cr2O3. This dense oxide layer can effectively protect the cladding alloy from further oxidation. According to the Co-Cr binary phase diagram, when the Cr element exceeds 43.9wt.%, the system becomes a Cr-based solid solution, so the Cr content cannot be too high.

[0036] Ni element in welding wire: According to the Co-Ni binary phase diagram, Ni can be infinitely dissolved in the Co matrix, so the addition of Ni can improve the strength of the Co matrix through solid solution strengthening. In addition, the addition of Ni element can further improve the high temperature resistance and creep strength of Co-based welding wire at high temperature.

[0037] W and C elements in welding wire: The main purpose of adding W and C elements is to generate W2C by in-situ reaction. W2C is a hard phase. Since it is generated in-situ during the reaction, it is dispersed in the cobalt matrix and has a good strengthening effect. The W2C hard phase also has the function of promoting heterogeneous nucleation, thereby refining the grains of the cobalt-based cladding layer and further enhancing the comprehensive performance of the cladding layer. In addition, a part of W will react with Co to generate a small amount of Co3W, further enhancing the performance of the cobalt matrix.

[0038] Fe element in welding wire: According to the Co-Fe binary phase diagram, Fe can be infinitely dissolved in the Co matrix, so the addition of Fe can improve the strength of the Co matrix through solid solution strengthening. In addition, the addition of Fe element can improve the surfacing forming performance of Co-based welding wire and improve the fluidity of the molten pool.

[0039] Mo element in welding wire: According to the Co-Mo binary phase diagram, the maximum solid solubility of Mo in the cobalt matrix is ​​14wt.%. Mo is solid-dissolved in the cobalt matrix and plays a role in solid solution strengthening. Another important role of Mo in welding wire is to generate Co3Mo2Si phase in situ with Co and Si. This phase is a Laves phase that is dispersed in the cobalt matrix and can significantly improve the high-temperature abrasion resistance of the cobalt matrix.

[0040] Mn and Si in welding wire: Mn is an important deoxidizing element, which increases the oxygen content in the cladding layer and avoids the formation of pores; Si also has a deoxidizing effect, and when Si and Mn are added together, the deoxidation effect is better. In addition, an important role of Si is to react with Co and Mo to form Co3Mo2Si hard phase.

[0041] After the welding wire is prepared, it is wound onto a wire reel by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for standby use.

[0042] Example 1 The method for preparing the welding wire based on the cobalt-based material of the present invention comprises the following specific steps: Step 1: Weigh 50.0% Cr, 5.0% Ni, 6.0% C, 8.0% Mo, 2.0% W, 0.5% Mn, 2.5% Si, and the rest Fe by mass percentage, and the sum of the mass percentages of the above components is 100%; Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace and heat for 1 hour at a temperature of 200° C. to remove crystal water and obtain a powder; then place the powder into a powder mixer and stir for 1 hour at a stirring rate of 60 r / min to obtain a cobalt-containing material; Step 3: Use alcohol to remove grease from the surface of the CoCr20W15Ni strip to obtain an outer skin, and then wrap the outer skin with a cobalt-containing base material to obtain a core roll; Step 4: Place the core coil into a drawing die for drawing to obtain welding wire A based on cobalt-containing base material.

[0043] The particle size of Cr, Ni, Mo, W, Mn and Fe is all 100 mesh.

[0044] The filling rate of the cobalt-based material in the welding wire A based on the cobalt-based material is 20%.

[0045] The diameter of the welding wire A based on the cobalt-containing base material is 1.0 mm.

[0046] The maximum aperture of the drawing die is 2.6 mm, and multiple apertures are set in increments of 0.2 mm.

[0047] The welding wire A based on cobalt-based materials was clad on the surface of 15CrMo water-cooled wall tubes. The cladding process and the microstructure and performance tests of the cladding layer are as follows: (1) The cladding is carried out by MIG method, with a current of 150A, a voltage of 12V, a shielding gas of 99.999% argon, and a gas flow rate of 15ml / min. The arc is stable during the cladding process, and the cladding layer is beautifully formed, with no pores or cracks visible to the naked eye; (2) The morphology of the cladding layer at low magnification is columnar dendrites, the matrix structure is mainly α-Co and ε-Co, and Co3Mo2Si phase and W2C hard phase are distributed; (3) The microhardness of the cladding layer is 510HV0.3; (4) The high temperature erosion weight loss of the cladding layer at 600°C is 0.2 times that of the base material 15CrMo; (5) The bonding strength between the cladding layer and the 15CrMo water-cooled wall tube substrate is 580MPa.

[0048] Example 2 The method for preparing the welding wire based on the cobalt-based material of the present invention comprises the following specific steps: Step 1: Weigh 60.0% Cr, 8.0% Ni, 8.0% C, 10.0% Mo, 4.0% W, 0.8% Mn, 3.5% Si, and the rest Fe by mass percentage, and the sum of the mass percentages of the above components is 100%; Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating at a temperature of 260° C. for 3 hours to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring at a stirring rate of 90 r / min for 3 hours to obtain a cobalt-containing material; Step 3: Use alcohol to remove grease from the surface of the CoCr20W15Ni strip to obtain an outer skin, and then wrap the outer skin with a cobalt-containing base material to obtain a core roll; Step 4: Place the core coil into a drawing die for drawing to obtain welding wire B based on cobalt-containing base material.

[0049] The particle size of Cr, Ni, Mo, W, Mn and Fe is all 200 mesh.

[0050] The filling rate of the cobalt-based material in the welding wire B based on the cobalt-based material is 22%.

[0051] The diameter of the welding wire B based on the cobalt-containing base material is 1.2 mm.

[0052] The maximum aperture of the drawing die is 2.4 mm, and multiple apertures are set in increments of 0.1 mm.

[0053] The welding wire B based on cobalt-based materials was clad on the surface of 15CrMo water-cooled wall tubes. The cladding process and the microstructure and performance tests of the cladding layer are as follows: (1) The cladding is carried out by MIG method, with a current of 200A, a voltage of 14V, a shielding gas of 99.999% argon, and a gas flow rate of 15ml / min. The arc is stable during the cladding process, and the cladding layer obtained is beautifully formed, with no pores or cracks visible to the naked eye; (2) The morphology of the cladding layer under low magnification is columnar dendrites, the matrix structure is mainly α-Co and ε-Co, and Co3Mo2Si phase and W2C hard phase are distributed; (3) The microhardness of the cladding layer is 510HV0.3; (4) The high temperature erosion weight loss of the cladding layer at 600°C is 0.2 times that of the base material 15CrMo; (5) The bonding strength between the cladding layer and the 15CrMo water-cooled wall tube substrate is 580MPa.

[0054] Figure 1 The cross-sectional metallographic structure of the cladding layer is shown in the cladding of water-cooled wall tubes based on the welding wire B containing cobalt-based materials. It can be seen that the structure of the cladding layer under low magnification is mainly columnar dendrites, and no defects such as pores, cracks, and inclusions are found.

[0055] Figure 2 The cross-section of the cladding layer is morphologically scanned by a high-power scanning electron microscope for cladding of water-cooled wall tubes using welding wire B containing cobalt-based materials. It can be seen that the Co3Mo2Si phase and W2C hard phase in the cladding layer are distributed on the cobalt matrix.

[0056] Figure 3 The high temperature erosion morphology of the surfacing layer is shown in the surfacing welding of the water-cooled wall tube based on the welding wire B containing cobalt-based materials. It can be seen that the high temperature erosion morphology of the surfacing layer is uniform, without large pieces of peeling, and the surface has excellent high temperature erosion resistance.

[0057] Example 3 The method for preparing the welding wire based on the cobalt-based material of the present invention comprises the following specific steps: Step 1: Weigh 55.0% Cr, 7.0% Ni, 7.2% C, 9.0% Mo, 3.2% W, 0.71% Mn, 3.2% Si, and the rest Fe by mass percentage, and the sum of the mass percentages of the above components is 100%; Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating at a temperature of 240° C. for 2 hours to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring at a stirring rate of 80 r / min for 2 hours to obtain a cobalt-containing material; Step 3: Use alcohol to remove grease from the surface of the CoCr20W15Ni strip to obtain an outer skin, and then wrap the outer skin with a cobalt-containing base material to obtain a core roll; Step 4: Place the core coil into a drawing die for drawing to obtain a welding wire C based on a cobalt-containing material.

[0058] The particle size of Cr, Ni, Mo, W, Mn and Fe is all 160 mesh.

[0059] The filling rate of the cobalt-based material in the welding wire C based on the cobalt-based material is 21%.

[0060] The diameter of the welding wire C based on the cobalt-containing base material is 1.1 mm.

[0061] The maximum aperture of the drawing die is 2.0 mm, and multiple apertures are set in increments of 0.25 mm.

[0062] The weld skin is CoCr20W15Ni strip with a thickness of 0.4 mm and a width of 7 mm.

[0063] Example 4 The method for preparing the welding wire based on the cobalt-based material of the present invention comprises the following specific steps: Step 1: Weigh 53.0% Cr, 7.5% Ni, 7.1% C, 9.5% Mo, 2.4% W, 0.67% Mn, 2.85% Si, and the rest Fe by mass percentage, and the sum of the mass percentages of the above components is 100%; Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating at a temperature of 230° C. for 1.5 h to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring at a stirring rate of 70 r / min for 1.5 h to obtain a cobalt-containing material; Step 3: Use alcohol to remove grease from the surface of the CoCr20W15Ni strip to obtain an outer skin, and then wrap the outer skin with a cobalt-containing base material to obtain a core roll; Step 4: Place the core coil into a drawing die for drawing to obtain a welding wire D based on a cobalt-containing material.

[0064] The particle size of Cr, Ni, Mo, W, Mn and Fe is all 130 mesh.

[0065] The filling rate of the cobalt-based material in the welding wire D based on the cobalt-based material is 20.5%.

[0066] The diameter of the welding wire D based on the cobalt-containing base material is 1.15 mm.

[0067] The maximum aperture of the drawing die is 2.0 mm, and multiple apertures are set in increments of 0.15 mm.

Claims

1. A cobalt-based material, characterized in that: It is composed of the following components in mass percentage: 50.0~60.0% Cr, 5.0~8.0% Ni, 6.0~8.0% C, 8.0~10.0% Mo, 2.0~4.0% W, 0.5~0.8% Mn, 2.5~3.5% Si, and the rest is Fe. The sum of the mass percentages of the above components is 100%.

2. The cobalt-containing material according to claim 1, characterized in that The particle sizes of Cr, Ni, Mo, W, Mn and Fe are all 100-200 meshes.

3. A method for preparing a cobalt-based material, characterized in that: The specific steps are as follows: Step 1, weigh the following components according to mass percentage: 50.0-60.0% Cr, 5.0-8.0% Ni, 6.0-8.0% C, 8.0-10.0% Mo, 2.0-4.0% W, 0.5-0.8% Mn, 2.5-3.5% Si, and the rest is Fe, and the sum of the mass percentages of the above components is 100%; Step 2: Place the Cr, Ni, C, Mo, W, Mn, Si and Fe weighed in step 1 into a vacuum heating furnace for heating to remove crystal water and obtain a powder; then place the powder into a powder mixer for stirring to obtain a cobalt-containing material.

4. The method for preparing a cobalt-containing base material according to claim 3, characterized in that: The heating temperature is 200-260° C., the heating time is 1-3 hours, the stirring time is 1-3 hours, and the stirring rate is 60-90 r / min.

5. A welding wire based on a cobalt-containing base material, characterized in that: It comprises a welding skin, wherein the welding skin is coated with the cobalt-containing base material as claimed in claim 1.

6. The method for preparing a welding wire based on a cobalt-containing material according to claim 5, characterized in that: The specific steps are as follows: Step 1, remove the grease on the surface of the CoCr20W15Ni strip with alcohol to obtain the outer skin; Step 2, wrapping the outer skin with the cobalt-containing base material according to claim 1 to obtain a core roll; Step 3: Place the core coil into a drawing die for drawing to obtain a welding wire based on a cobalt-containing material.

7. The method for preparing a welding wire based on a cobalt-containing material according to claim 6, characterized in that: The drawing die has multiple apertures, the apertures are 2.6-1.0 mm, and the apertures in the drawing die are arranged in order from large to small.

8. The method for preparing a welding wire based on a cobalt-containing material according to claim 6, characterized in that: The filling rate of the cobalt-based material in the welding wire based on the cobalt-based material is 20-22%.

9. The method for preparing a welding wire based on a cobalt-containing material according to claim 7 or 8, characterized in that: The diameter of the welding wire based on the cobalt-containing base material is 1.0-1.2 mm.

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