Layered surfacing process for duplex stainless steel base metal

Abstract

The invention discloses a duplex stainless steel base metal layered surfacing welding process, which adopts a surfacing welding machine to build up a nickel-based alloy welding material on a duplex stainless steel base metal in a gas shielded welding state, and specifically comprises the following steps: controlling the temperature of the base metal before welding, controlling the preheating temperature between 10 DEG C and 20 DEG C, and adopting a multi-layer welding mode according to the structure and use requirements of the base metal, the method comprises the following steps: firstly, carrying out surfacing on a first layer, then sequentially carrying out surfacing on a next layer, and when the interlayer temperature reaches 145-150 DEG C and the interlayer temperature is reduced to 28-32 DEG C by using a cooling device, carrying out surfacing again, adopting an S31803 material as a duplex stainless steel base material, and adopting an ERNiCrMo-3 argon arc welding wire as a nickel-based alloy welding material. By means of the method, welding of the nickel-based alloy and the duplex stainless steel can be achieved, on the basis that the corrosion resistance of the duplex stainless steel is guaranteed, the material abrasion resistance is improved, the percent of pass of a surfacing layer is increased, the problems of hot cracks, air holes, intergranular corrosion of a welding joint and the like in the welding process of the nickel-based alloy and the high-strength steel are solved, and the welding quality and the use performance are guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and specifically relates to a multi-layer surfacing welding process for duplex stainless steel base materials. Background Art

[0002] For stainless steel used in offshore engineering equipment, chloride ion corrosion and microbial corrosion in seawater have always been recognized worldwide problems. Through research, it is found that duplex stainless steel has strong resistance to chloride ion corrosion and microbial corrosion. Some special components in offshore engineering not only require corrosion resistance but also high hardness and wear resistance. Comparing existing domestic and foreign technologies, it is found that in order to achieve the wear resistance of equipment, nickel-based alloys are generally surfacing welded on high-strength steel.

[0003] Although existing welding technologies can achieve the welding of nickel-based alloys and high-strength steel, problems such as hot cracks, pores, and intergranular corrosion of welded joints during the welding process seriously affect the welding quality and service performance. In addition, factors such as the selection of welding process parameters and the matching of welding materials also have an important impact on the welding quality. Therefore, in-depth research on the surfacing welding process of nickel-based alloys on high-strength steel, optimizing welding parameters and material matching, is of great significance for improving welding quality and the performance of engineering structures. Summary of the Invention

[0004] The present invention aims at the above problems existing in the prior art and provides a multi-layer surfacing welding process for duplex stainless steel base materials. The present invention can achieve the welding of nickel-based alloys and duplex stainless steel, improve the wear resistance of materials on the basis of ensuring the corrosion resistance of duplex stainless steel, improve the qualification rate of the surfacing layer, solve problems such as hot cracks, pores, and intergranular corrosion of welded joints during the welding process of nickel-based alloys and high-strength steel, and ensure the welding quality and service performance.

[0005] The technical solution adopted by the present invention to solve its technical problems is: A multi-layer surfacing welding process for duplex stainless steel base materials, using a surfacing welding machine to surfacing weld nickel-based alloy welding materials onto a duplex stainless steel base material under the condition of gas shielded welding, specifically including the following steps: Control the temperature of the base material before welding, with the preheating temperature between 10°C and 20°C. According to the structure and usage requirements of the base material, adopt a multi-layer welding method. First, perform the surfacing of the first layer, and then sequentially perform the surfacing of the next layer. When the interlayer temperature reaches 145 - 150°C, use a cooling device to reduce the interlayer temperature to 28 - 32°C and then perform surfacing again.

[0006] The duplex stainless steel base material uses S31803 material.

[0007] The nickel-based alloy welding consumables use ERNiCrMo-3 argon arc welding wire, grade: GTN-CM3, and the wire composition is as follows: C≤0.011, Si≤0.50, Mn≤0.06, P≤0.02, S≤0.015, Cr: 20.0-23.0, Mo: 8.0-10.0, Ni: ≥58.0, Cu≤0.50, Fe≤1.0, Nb+Ta: 3.15-4.15.

[0008] The welding process parameters include a welding peak current of 215-225A, a hot wire current of 50-55A, a welding speed of 280-320 mm / min, and a wire feeding speed of 1000-2000 mm / min; pulsed welding, and the pulse width ratio for automatic welding is 30-80%. Before welding, clean the impurities on the surface of the base metal to be surfacing and the surface of the welding consumables, and keep the surface to be surfacing clean.

[0009] Use a stainless steel brush to remove the impurities on the surface of the base metal completely and polish it to a metallic luster, and use an acetone solution to remove the impurities on the surface of the welding consumables completely.

[0010] The welding equipment uses a surfacing welding machine.

[0011] The gas shielded welding uses non-consumable electrode inert gas shielded welding, and the shielding gas is 99.997% Ar; the selected shielding gas flow rate is 12-25L / min.

[0012] The preheating temperature and interpass temperature are measured by a contact type temperature measuring instrument.

[0013] The beneficial effects of the present invention are: 1. The process of the present invention solidifies the surfacing parameters and verifies the feasibility of surfacing nickel-based welding consumables on duplex stainless steel, which can ensure the strength of the base metal, improve the wear resistance of the material on the basis of ensuring the corrosion resistance of duplex stainless steel, increase the corrosion resistance and wear resistance of the material surface, improve the qualification rate of the surfacing layer. After the product structure is surfaced by the present invention, problems such as hot cracks, pores, and intergranular corrosion of the welded joint can meet the standards and process requirements, solve the problems of hot cracks, pores, and intergranular corrosion of the welded joint existing in the welding process of nickel-based alloy and high-strength steel, and ensure the welding quality and service performance.

[0014] 2. The present invention controls and preheats the temperature of the base material before welding, with the preheating temperature being between 10°C and 20°C. According to the structure and usage requirements of the base material, a multi-layer welding method is adopted, such as a two-layer or three-layer surfacing method. First, the first layer of surfacing is carried out, and then the next layer of surfacing is carried out in sequence. When the interlayer temperature reaches 145 - 150°C, since the material properties deteriorate when the interlayer temperature is too high and the efficiency decreases when the temperature is too low, the interlayer temperature is reduced to 28 - 32°C by using a cooling device and then surfacing is carried out again, thus taking into account both the material properties and the working efficiency; the iron content on the surface of the surfacing layer after surfacing is ≤5%. Ensure that the pitting weight loss of the surfacing layer and the nearby heat-affected zone of the welded joint is less than 4.0 g / m 2 , the iron content of the surfacing layer 3 mm away from the duplex stainless steel is ≤10%, the intergranular corrosion rate of the surfacing layer is <0.911 mm / year, the PT qualification rate of the surfacing layer is 100%, and the UT qualification rate of the surfacing layer is 100%. By means of appropriate material matching and experimental optimization of welding process parameters, the welding quality is improved and the engineering structure performance is enhanced to meet the requirements of offshore engineering equipment.

[0015] 3. Before welding, impurities such as oil stains and iron ions on the surface of the base material to be surfaced and the welding material are cleaned. For example, the oxide layer on the surface of the base material is removed completely using a stainless steel brush and polished to a metallic luster; the oil stains and other impurities on the surface of the welding material are removed completely using an acetone solution, and the surface to be surfaced is kept clean to ensure the welding quality, improve the wear resistance of the material on the basis of ensuring the corrosion resistance of the duplex stainless steel, and meet the requirements of the process and standards. Specific embodiments

[0016] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following describes the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0017] A multi-layer surfacing process for a duplex stainless steel base material, in which a nickel-based alloy welding material is surfaced onto the duplex stainless steel base material by using a surfacing machine in the gas shielded welding state, specifically including the following steps: Before welding, the temperature of the base material is controlled, and the preheating temperature is between 10°C and 20°C. According to the structure and usage requirements of the base material, a multi-layer welding method is adopted, such as a two-layer, three-layer, five-layer, etc. surfacing method. First, the first layer of surfacing is carried out, and then the next layer of surfacing is carried out in sequence. When the interlayer temperature reaches 145 - 150°C, since the material properties deteriorate when the interlayer temperature is too high and the efficiency decreases when the temperature is too low, the interlayer temperature is reduced to 28 - 32°C by using a cooling device and then surfacing is carried out again, thus taking into account both the material properties and the working efficiency.

[0018] The duplex stainless steel base material is made of S31803 material. See Table 1. Before welding, grind the surface of the workpiece to a metallic luster.

[0019] The nickel-based alloy welding consumables adopt ERNiCrMo-3 argon arc welding wire, brand: GTN-CM3, and the chemical composition of the welding wire is as follows: C≤0.011, Si≤0.50, Mn≤0.06, P≤0.02, S≤0.015, Cr: 20.0-23.0, Mo: 8.0-10.0, Ni: ≥58.0, Cu≤0.50, Fe≤1.0, Nb+Ta: 3.15-4.15. See Table 2.

[0020] The welding process parameters include a welding peak current of 215-225A, a hot wire current of 50-55A, a welding speed of 280-320 mm / min, and a wire feeding speed of 1000-2000 mm / min; pulsed welding, and the pulse width ratio for automatic welding is 30-80%. Before welding, clean the oil stains, iron ions and other impurities on the surface of the base material to be surfacing and the welding consumables, and keep the surface to be surfacing clean. Specifically, a stainless steel brush can be used to remove the oxide layer on the surface of the base material and grind it to a metallic luster; an acetone solution can be used to remove the oil stains and other impurities on the surface of the welding consumables.

[0021] The welding equipment adopts a surfacing welding machine, such as a Fronius surfacing welding machine.

[0022] The gas shielded welding adopts non-consumable inert gas shielded welding, and the shielding gas is 99.997% Ar. The selected shielding gas flow rate is 12-25L / min.

[0023] The preheating temperature and interpass temperature are measured by a contact type temperature measuring instrument.

[0024] Example 1: This example provides a welding process method for surfacing an ERNiCrMo-3 nickel-based alloy corrosion-resistant layer on a S31803 duplex stainless steel base material. Specifically, it is to perform corrosion-resistant layer surfacing on the surface of a 25mm thick S31803 duplex stainless steel plate; the chemical composition of the base material is shown in Table 1, and the materials used for surfacing are ERNiCrMo-3 φ1.2mm, and the chemical composition of the welding consumables is shown in Table 1 and Table 2. The specific steps are as follows: Before surfacing, remove the oil stain impurities on the surface of the welding consumables and the base material specimens, use a stainless steel brush to remove the oxide layer on the surface of the test tube and grind it to a metallic luster, and use an acetone solution to remove the oil stains on the surface of the welding wire.

[0025] The preheating temperature is 15°C. During the welding process, a contact thermometer is used to measure the interlayer temperature. When the interlayer temperature reaches 148°C, the temperature of the specimen is reduced to 30°C by physical cooling before welding. The surfacing welding is carried out by Fronius mobile hot wire Tig welding, with a shielding gas of 99.997% Ar and pulsed welding. The specific welding process parameters are shown in Table 3.

[0026] Example 2: This example provides a welding process method for surfacing an ERNiCrMo-3 nickel-based alloy corrosion-resistant layer on a base material of S31803 duplex stainless steel. Specifically, the corrosion-resistant layer is surfaced on the surface of a 25-mm-thick S31803 duplex stainless steel plate. The chemical composition of the base material is shown in Table 1, the material used for surfacing is ERNiCrMo-3 φ1.2 mm, and the chemical composition of the welding consumables is shown in Table 2. The preheating temperature is 10°C. During the welding process, a contact thermometer is used to measure the interlayer temperature. When the interlayer temperature reaches 150°C, the temperature of the specimen is reduced to 28°C by physical cooling before welding. The specific welding process parameters are shown in Table 4, and the others refer to Example 1.

[0027] Example 3: This example provides a welding process method for surfacing an ERNiCrMo-3 nickel-based alloy corrosion-resistant layer on a base material of S31803 duplex stainless steel. Specifically, the corrosion-resistant layer is surfaced on the surface of a 25-mm-thick S31803 duplex stainless steel plate. The chemical composition of the base material is shown in Table 1, the material used for surfacing is ERNiCrMo-3 φ1.2 mm, and the chemical composition of the welding consumables is shown in Table 2. The preheating temperature is 10°C. During the welding process, a contact thermometer is used to measure the interlayer temperature. When the interlayer temperature reaches 145°C, the temperature of the specimen is reduced to 32°C by physical cooling before welding. The specific welding process parameters are shown in Table 5, and the others refer to Example 1.

[0028] Example 4: This example provides a welding process method for surfacing an ERNiCrMo-3 nickel-based alloy corrosion-resistant layer on a base material of S31803 duplex stainless steel. Specifically, the corrosion-resistant layer is surfaced on the surface of a 25-mm-thick S31803 duplex stainless steel plate. The chemical composition of the base material is shown in Table 1, the material used for surfacing is ERNiCrMo-3 φ1.2 mm, and the chemical composition of the welding consumables is shown in Table 2. The preheating temperature is 20°C. During the welding process, a contact thermometer is used to measure the interlayer temperature. When the interlayer temperature reaches 145°C, the temperature of the specimen is reduced to 28°C by physical cooling before welding. The specific welding process parameters are shown in Table 6, and the others refer to Example 1.

[0029] Example 5: This embodiment provides a welding process method for surfacing an erosion-resistant layer of ERNiCrMo-3 nickel-based alloy on the base material of S31803 duplex stainless steel. Specifically, an erosion-resistant layer is surfaced on the surface of an S31803 duplex stainless steel plate with a thickness of 25 mm. The chemical composition of the base material is shown in Table 1, and the material used for surfacing is ERNiCrMo-3 φ1.2 mm. The chemical composition of the welding consumables is shown in Table 2. The preheating temperature is 15 °C. During the welding process, a contact thermometer is used to measure the interlayer temperature. When the interlayer temperature reaches 145 °C, the temperature of the specimen is reduced to 30 °C by physical cooling and then welding is carried out. The specific welding process parameters are shown in Table 7, and other parameters refer to Embodiment 1.

[0030] Referring to Tables 3 to 7, the present invention selects 5 large groups of tests according to different welding process parameters, and each large group includes 3 small group comparative tests. The magnitude of the peak current (A) will directly affect the penetration depth during welding. The smaller the welding current, that is, the peak current (A), the smaller the penetration depth of the weld. When welding the first layer, the smaller the penetration depth, the less base material enters the surfacing layer. The base material contains a large amount of iron element, and the amount of iron element in the base material entering the surfacing layer will directly affect the corrosion resistance of the surfacing layer. Therefore, by controlling the magnitude of the welding current, the amount of iron element in the base material entering the surfacing layer is minimized as much as possible. However, it is not that the smaller the welding current, the better. If the welding current is too small, the fusion between the weld and the base material will become poor, and lack of fusion is likely to occur. The present invention has explored through experiments a welding current range that can not only ensure good fusion of the weld but also reduce iron element dilution, thus solving the problems of poor corrosion resistance and wear resistance of duplex stainless steel existing in the prior art. The specific welding process parameters are shown in Tables 3-7.

[0031] After welding, the surface of the surfacing layer is subjected to penetrant and ultrasonic inspections, and tensile, bending, impact, pitting corrosion, intergranular corrosion, macro, hardness, micro, ferrite content tests are carried out. The specific test results are shown in Table 8.

[0032] Table 1 Chemical Composition Table of Duplex Stainless Steel Plate S31803

[0033] Table 2 Chemical Composition Table of ERNiCrMo-3 Nickel-Based Alloy

[0034] Table 3 Welding Process Parameters of the First Group

[0035] Table 4 Welding Process Parameters of the Second Group

[0036] Table 5 Welding Process Parameters of the Third Group

[0037] Welding process parameters of Group 4 in Table 6

[0038] Welding process parameters of Group 5 in Table 7

[0039] Test results in Table 8

[0040] Combined with Tables 3 to 8, it can be seen that: by using the method of surfacing nickel-based alloy on duplex stainless steel of the present invention, under the process parameters of Group 2, Group 3, and Group 4, the welding process qualification results are as follows: the pitting weight loss of the surfacing layer and the heat-affected zone near the welding joint is less than 4.0 g / m 2 , the iron content of the surfacing layer 3 mm away from the duplex stainless steel ≤ 10%, the intergranular corrosion rate of the surfacing layer < 0.911 mm / year, the PT qualification rate of the surfacing layer is 100%, and the UT qualification rate of the surfacing layer is 100%. That is, all indicators can meet the requirements of relevant standards. Among them, Group 1 and Group 5 have items that do not meet the relevant standards. Therefore, the present invention improves the welding quality and the engineering structure performance by appropriate material matching and experimental optimization of welding process parameters to meet the requirements of offshore engineering equipment.

[0041] The above is the preferred embodiment of the present invention. The description of specific embodiments is only for better understanding the idea of the present invention. For those of ordinary skill in the art, several improvements or equivalent substitutions can be made according to the principle of the present invention, and these improvements or equivalent substitutions are also regarded as falling within the protection scope of the present invention.

Claims

1. A method for multi-layer surfacing of a duplex stainless steel base material, which uses a surfacing machine to surfacing nickel-based alloy welding materials onto the duplex stainless steel base material under the condition of gas shielded welding, characterized in that, Specifically, it includes the following steps: Before welding, control the temperature of the base metal, with the preheating temperature between 10°C and 20°C. According to the structure and usage requirements of the base metal, adopt the multi-layer welding method. First, carry out the surfacing of the first layer, and then successively carry out the surfacing of the next layer. When the interlayer temperature reaches 145 - 150°C, use the cooling device to reduce the interlayer temperature to 28 - 32°C and then carry out surfacing again.

2. The multi-layer surfacing process for duplex stainless steel base material according to claim 1, wherein, The duplex stainless steel base metal adopts the S31803 material.

3. The duplex stainless steel base metal multi-layer surfacing process according to claim 2, characterized in that, The nickel-based alloy welding consumables adopt the ERNiCrMo-3 argon arc welding wire, brand: GTN-CM3, and the wire composition is as follows: C≤0.011, Si≤0.50, Mn≤0.06, P≤0.02, S≤0.015, Cr: 20.0 - 23.0, Mo: 8.0 - 10.0, Ni: ≥58.0, Cu≤0.50, Fe≤1.0, Nb+Ta: 3.15 - 4.

15.

4. The multi-layer surfacing process for duplex stainless steel base materials as described in claim 3, characterized in that, The welding process parameters include that the welding peak current is 215 - 225A, the hot wire current is 50 - 55A, the welding speed is 280 - 320 mm / min, and the wire feeding speed is 1000 - 2000 mm / min; pulsed welding, and the duty cycle of the automatic welding is 30 - 80%.

5. The duplex stainless steel base material multi-layer surfacing process according to claim 1, characterized in that, Before welding, clean the impurities on the surface of the base metal to be surfaced and the surface of the welding consumables, and keep the surface to be surfaced clean.

6. The duplex stainless steel base material multi-layer surfacing process according to claim 5, characterized in that, Use a stainless steel brush to remove the impurities on the surface of the base metal completely and polish it to a metallic luster, and use an acetone solution to remove the impurities on the surface of the welding consumables completely.

7. The multi-layer surfacing process for duplex stainless steel base materials according to claim 1, characterized in that, The welding equipment adopts a surfacing machine.

8. The duplex stainless steel base material multi-layer surfacing process according to claim 1, characterized in that, The gas shielded welding adopts non-consumable inert gas shielded welding, and the shielding gas is 99.997% Ar; the selected shielding gas flow rate is 12 - 25L / min.

9. The multi-layer surfacing process for duplex stainless steel base material according to claim 1, characterized in that, The preheating temperature and the interlayer temperature are measured by a contact type temperature measuring instrument.

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