Martensitic stainless steel welding wire, preparation method thereof and application of martensitic stainless steel welding wire in gas metal arc welding

Abstract

The invention discloses a martensitic stainless steel welding wire, a preparation method of the martensitic stainless steel welding wire and application of the martensitic stainless steel welding wire in gas metal arc welding, and belongs to the technical field of welding materials and preparation of the welding materials. The martensitic stainless steel welding wire for gas metal arc welding solves the problems that when an existing martensitic stainless steel welding wire for gas metal arc welding is used for welding large structural parts, welding seam forming is poor, and the number of welding seam pores is large. In the preparation process of the martensitic stainless steel welding wire, except for the last pass of drawing, a roller drawing process without adding wire drawing powder is adopted, the use of the wire drawing powder is reduced, meanwhile, an electrolytic pickling process and a cleaning process are added in the follow-up process, residues of pollutants such as the wire drawing powder and oil sludge on the surface of the welding wire are reduced, and the service life of the welding wire is prolonged. And therefore, welding spatter and welding seam air hole sensitivity are greatly reduced. And the surface of the welding wire is coated with fluorocarbon chain oil through a rope oiling method, and the situation that the sensitivity of weld pores is increased due to hydrogen generated through decomposition in the welding process is avoided.

Description

Technical Field

[0001] The invention relates to a martensitic stainless steel welding wire and a preparation method thereof and application in metal-electrode gas shielded welding, belonging to the technical field of welding materials and preparation thereof. Background Art

[0002] Gas metal arc welding has been rapidly developed and widely used at home and abroad due to its advantages of high production efficiency, low welding cost and strong process adaptability. For example, it has become one of the most important welding methods for metal materials such as low-carbon steel, low-alloy steel and stainless steel. Therefore, the demand for gas shielded welding wire is increasing.

[0003] At present, welding components tend to be larger, with more complex structures and harsher service conditions, so higher requirements are placed on the process performance of welding wires. The process performance of welding wires mainly includes arc stability, welding spatter, weld formation, porosity sensitivity, etc. This is mainly because: whether the welding arc is stable has a great influence on the stability of the welding process and the formation of the weld; a large amount of welding spatter will not only destroy the stability of the arc, reduce the utilization rate of the welding wire, and increase the amount of post-weld cleaning, but also the spattered metal will easily clog the conductive nozzle and the nozzle, and in severe cases, the welding process will be interrupted; the weld formation not only affects the beauty of the welded structure, but also affects the mechanical properties of the welded joint. Poor formation will cause stress concentration and reduce the safety of the structure; when the porosity sensitivity of the welding wire is high, a large number of pores will be formed in the weld, which will greatly deteriorate the mechanical properties of the welded joint and reduce the quality of the product.

[0004] The production of welding wire consists of heat treatment, surface treatment, drawing and other processes, which will affect the quality of the finished welding wire and further affect the performance of the welding wire. Especially in the preparation process of martensitic stainless steel welding wire, when the martensitic stainless steel wire rod is drawn to a certain extent, serious work hardening will occur. Annealing treatment is required to improve the plasticity and processing performance of the wire rod to prepare for the next step of drawing. In addition, if the finished welding wire is too soft, it will cause small bends, resulting in instability of wire feeding and arc; if it is too hard, it will cause greater stress in the welding wire, which is not conducive to welding operation. Heat treatment can control the strength of the finished welding wire and ensure its welding processability. Surface treatment is crucial to the quality of welding wire. Surface treatment includes pickling, electrolysis, cleaning, oiling and drying. After annealing, the surface of the welding wire is prone to form hard and brittle oxide scale, which will scratch the mold, hinder plastic deformation during drawing, and affect the quality of the welding wire. The pickling process can remove the oxide scale formed during the rolling and heat treatment of the wire rod. Drawing powder and oil attached to the surface of the welding wire will cause spatter and smoke during welding. The electrolytic pickling process can wash away the drawing powder and sludge remaining on the surface of the welding wire. Electrolytic pickling can also reduce the surface defects of the welding wire and improve the surface quality of the welding wire. The purpose of online cleaning is to further remove carbon black, oil, sulfuric acid and other contaminants on the surface of the welding wire to achieve the effect of cleaning the surface, thereby obtaining a bright welding wire. The high temperature during welding will soften the copper conductive nozzle. The friction between the harder welding wire and the conductive nozzle will cause serious wear of the conductive nozzle. Oiling the surface of the welding wire can reduce the contact resistance and friction between the welding wire and the conductive nozzle, thereby reducing the wear of the conductive nozzle; in addition, oiling the welding wire can effectively solve the problems of wire feeding and rust. The purpose of drying is to dry the welding wire, prevent the residual water in the welding wire preparation process, and avoid problems such as pores and hydrogen cracking caused by excessive moisture in the welding wire entering the weld. Improper process during wire drawing will cause the welding wire to be bamboo-shaped and have defects such as scratches, pits, cracks, twists, and breaks, which will affect the quality of the finished welding wire, reduce the yield rate, and reduce the process performance of the welding wire. The factors affecting drawing mainly include mold material, lubricant type, total surface reduction rate, and pass surface reduction rate. Increasing the hardness of the mold and reducing the surface roughness of the die hole can reduce the friction of wire drawing and improve the drawing efficiency; at the same time, suitable wire drawing lubricants need to be used during the drawing process to reduce friction, which can not only reduce the wear of the wire drawing die and increase the service life of the die, but also increase the surface brightness of the welding wire and improve the surface quality of the welding wire. At present, most martensitic stainless steel welding wires use carbide dies and dry powdered fatty acid soap lubricants to achieve good drawing effects. When drawing martensitic stainless steel welding wires, it is advisable to use a higher total surface reduction rate and more drawing passes, which is conducive to obtaining welding wires with higher surface finish.

[0005] However, the existing preparation technology for the martensitic stainless steel welding wire for metal arc welding has problems such as poor weld formation and many weld pores when welding large turbine runners, which seriously affects the quality of welding and causes a high rate of post-weld repair. Therefore, it is very necessary to prepare a martensitic stainless steel welding wire with low porosity sensitivity and good weld formation. Summary of the invention

[0006] Aiming at the problems of poor weld formation and many weld pores in existing martensitic stainless steel welding wire for metal arc welding when welding large structural parts, the present invention provides a martensitic stainless steel welding wire and a preparation method thereof and application in metal arc welding.

[0007] The technical solution of the present invention:

[0008] One of the objects of the present invention is to provide a method for preparing a martensitic stainless steel welding wire, which is characterized by comprising:

[0009] (1) Tempering: Tempering the martensitic stainless steel wire rod to obtain tempered martensite structure and improve the plasticity and toughness of the wire;

[0010] (2) Pickling: Pickling is performed with a mixed acid obtained by mixing 6-8% H2SO4, 6-8% HCl and 2-4% HNO3, and the treatment time is 5 min;

[0011] (3) Rough drawing: After tempering and pickling, the martensitic stainless steel wire rod is drawn through one roller to a 2.5 mm welding wire;

[0012] (4) Bright annealing: The 2.5 mm welding wire obtained in (3) is subjected to bright annealing to obtain a wire material with a strength of 800 to 1200 MPa;

[0013] (5) First fine drawing: 2.5 mm welding wire is drawn to 1.6 mm welding wire through one roller pass;

[0014] (6) Electrolytic pickling: Use H2SO4 solution for electrolytic pickling to improve the surface cleanliness of the welding wire;

[0015] (7) Second fine drawing: The 1.6 mm welding wire is drawn by rollers once to a 1.4 mm welding wire, and then the 1.4 mm welding wire is drawn by linear drawing once to a 1.2 mm welding wire, and dry powdered fatty acid soap lubricant is used as drawing powder during the wire drawing process;

[0016] (8) Online cleaning: Use steel wool dry wiping and steam cleaning to clean the wire drawing powder, oil sludge and other residues on the surface of the welding wire;

[0017] (9) Oiling: Use the wire rope oiling method to apply perfluoropolyether oil on the surface of the welding wire to reduce the wear of the welding wire on the conductive nozzle and improve the wire feeding performance;

[0018] (10) Drying, winding and packaging: The oiled welding wire is dried in a drying oven, then wound into a welding wire coil using a precision layer winding machine, and finally packaged using an automatic packaging machine.

[0019] It is further defined that the martensitic stainless steel wire rod in (1) is HS13 / 5LA martensitic stainless steel wire rod.

[0020] It is further defined that the tempering temperature in (1) is 600-620°C and the time is 1 hour.

[0021] It is further defined that the bright annealing treatment temperature in (4) is 800-850°C and the wire speed is 6-8 m / min.

[0022] It is further defined that the concentration of the H2SO4 solution in (6) is 16-20%, the electrolysis current is 15-25A, the length of the electrolyte acid tank is 20m, and the wire feeding speed is 100m / min.

[0023] It is further defined that the oiling parameters in (9) are: oil volume 0.1-0.3 mL / min, wire rope speed 6-12 cm / min, wire feeding speed 300-350 m / min.

[0024] It is further defined that the drying temperature in (10) is 300°C and the temperature is kept at this temperature for 3 hours.

[0025] A second object of the present invention is to provide a martensitic stainless steel welding wire prepared by the above method.

[0026] It is further defined that the martensitic stainless steel welding wire has the advantages of smooth surface, good drawing quality, small welding spatter and smoke, good weld formation, and low weld porosity sensitivity.

[0027] The third object of the present invention is to provide an application of the above-mentioned martensitic stainless steel welding wire, specifically for metal arc welding.

[0028] It is further defined as being for welding a martensitic stainless steel turbine runner.

[0029] A fourth object of the present invention is to provide a welding method for Cr13Ni5 type martensitic stainless steel, specifically using the above-mentioned martensitic stainless steel welding wire and adopting the metal arc welding method to perform welding.

[0030] It is further defined that the current type during the welding process is DCEP, the welding current is 220-240A, the arc voltage is 28-30V, the shielding gas is composed of Ar and CO2 in a volume ratio of 95%:5%, the flow rate of the shielding gas is 18-20L / min, and the interlayer temperature is less than 100°C.

[0031] Beneficial effects:

[0032] (1) The martensitic stainless steel welding wire prepared by the present invention has uniform surface quality, high surface finish, and no drawing defects. It can be applied to the MAG welding method. During the welding process, the arc is stable, the welding spatter is small, the welding smoke is small, and the weld formation is good.

[0033] (2) In the preparation process of the martensitic stainless steel welding wire provided by the present invention, except for the last drawing pass, a roller drawing process without adding wire drawing powder is adopted, thereby reducing the use of wire drawing powder. At the same time, an electrolytic pickling process and a cleaning process are added in the subsequent process, thereby reducing the residue of pollutants such as wire drawing powder and sludge on the surface of the welding wire, thereby greatly reducing welding spatter and weld porosity sensitivity.

[0034] (3) The present invention adopts a wire rope oiling method to carry out the oiling process, thereby avoiding the reuse of wire ropes and oil. At the same time, the amount of oil applied can be accurately controlled by the amount of oil, the wire rope speed and the wire feeding speed. In this process, a carbon fluorine chain oil is used instead of a hydrocarbon chain oil to avoid the decomposition and generation of hydrogen during the welding process, thereby increasing the porosity sensitivity of the weld. At the same time, a drying process is added to remove the moisture remaining on the surface of the welding wire to avoid moisture entering the welding environment.

[0035] (4) According to NB / T 47013.2-2015 “Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing”, the MAG weld metal of the martensitic stainless steel welding wire prepared by the present invention was subjected to radiographic testing, and the test result was Level I. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The radiographic detection result of the weld metal obtained in Example 1;

[0037] Figure 2 The radiographic detection result of the weld metal obtained in Example 2;

[0038] Figure 3 The radiographic test results of the weld metal obtained in Comparative Example 1;

[0039] Figure 4 The radiographic test results of the weld metal obtained in Comparative Example 2;

[0040] Figure 5 This is the radiographic inspection result of the weld metal obtained in Comparative Example 3. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned objects, 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.

[0042] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0043] 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.

[0044] 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 by those skilled in the art through commercial channels, and the purity of the solid and liquid reagents used is analytically pure.

[0045] Example 1

[0046] (1) A HS13 / 5LA martensitic stainless steel wire rod with a diameter of 5.5 mm was used as a wire, loaded into a resistance furnace, heated to 600°C, and kept warm for 1 h to obtain a tempered martensitic structure and improve the plasticity and toughness of the wire.

[0047] (2) The tempered wire was pickled with a mixed acid solution of 8% H2SO4, 8% HCl and 4% HNO3 for 5 min to remove the oxide scale.

[0048] (3) Use a roller die wire drawing machine to directly draw the wire from 5.5 mm to 2.5 mm.

[0049] (4) The wire is further annealed in a bright annealing furnace, the furnace is filled with hydrogen, the heating temperature is 800° C., the wire speed is 6 m / min, and a wire with a strength of 950 MPa is obtained.

[0050] (5) Use a roller die wire drawing machine to continue drawing to 1.6 mm.

[0051] (6) Use 20% H2SO4 solution for electrolytic pickling, the electrolysis current is 25A, the electrolyte acid tank length is 20m, and the wire speed is 100m / min to improve the surface cleanliness of the welding wire.

[0052] (7) A roller die wire drawing machine is used to continue drawing to 1.4 mm, and then a linear wire drawing machine is used to draw to 1.2 mm through one pass. The die material is cemented carbide, and the wire drawing powder is a dry powder fatty acid soap lubricant, specifically commercially available V60 wire drawing powder.

[0053] (8) Use dry wiping with steel wool combined with steam cleaning to perform online cleaning to remove wire drawing powder, oil sludge and other residues on the surface of the welding wire.

[0054] (9) Use a wire oiling device to apply perfluoropolyether oil on the surface of the welding wire, with an oil volume of 0.1 mL / min, a wire speed of 6 cm / min, and a wire feeding speed of 300 m / min to reduce the wear of the welding wire on the conductive nozzle and improve the wire feeding performance.

[0055] (10) The oiled welding wire is placed in a drying box, heated to 300°C, and kept warm for 3 hours. The moisture remaining on the surface of the welding wire during the production process is removed through the drying process. The welding wire is then wound using a precision layer winding machine to form a 15 kg welding wire reel, which is then packaged using an automatic packaging machine.

[0056] The mechanical properties of the welding wire prepared in this example were characterized, and the results showed that the tensile strength was 1400-1600 MPa.

[0057] The welding wire was further used to prepare the MAG weld metal. The welding current type was DCEP, the welding current was 240A, the arc voltage was 29V, the shielding gas was 95% Ar + 5% CO2, the gas flow rate during welding was 20L / min, and the interlayer temperature was less than 100°C. According to NB / T 47013.2-2015 "Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing", the weld metal was radiographically tested, and the test result was Level I. Figure 1 The various process properties of welding wire are shown in Table 1.

[0058] Example 2

[0059] The differences between this embodiment and embodiment 1 are as follows: in step (9), the oil volume is 0.3 mL / min, the wire rope speed is 12 cm / min, the wire feeding speed is 350 m / min, and the remaining process steps and parameter settings are the same as those in embodiment 1.

[0060] The mechanical properties of the welding wire prepared in this example were characterized, and the results showed that the tensile strength was 1400-1600 MPa.

[0061] The welding wire was further used to prepare the MAG weld metal. The welding current type was DCEP, the welding current was 240A, the arc voltage was 29V, the shielding gas was 95% Ar + 5% CO2, the gas flow rate during welding was 20L / min, and the interlayer temperature was less than 100°C. According to NB / T 47013.2-2015 "Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing", the weld metal was radiographically tested, and the test result was Level I. Figure 2 The various process properties of welding wire are shown in Table 1.

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 1 is that in step (3), a linear wire drawing machine is used to draw the wire from 5.5 mm to 2.5 mm through 6 passes, and the drawing die is 5.0 mm, 4.5 mm, 4.0 mm, 3.5 mm, 3.0 mm and 2.5 mm respectively, the die material is cemented carbide, and the wire drawing powder is V60 wire drawing powder. The strength of the wire obtained in step (4) is 1000 MPa. Step (5) uses a linear wire drawing machine to continue drawing to 1.6 mm through 4 passes, and the drawing die is 2.2 mm, 2.0 mm, 1.8 mm and 1.6 mm respectively, the die material is cemented carbide, and the wire drawing powder is V60 wire drawing powder. Step (7) The wire is drawn to 1.2 mm in 4 passes using a linear wire drawing machine. The drawing dies are 1.5 mm, 1.4 mm, 1.3 mm and 1.2 mm respectively. The die material is cemented carbide and the wire drawing powder is V60 wire drawing powder. The remaining process steps and parameter settings are the same as those in Example 1.

[0064] The mechanical properties of the welding wire prepared in this comparative example were characterized, and the results showed that the tensile strength was 1400-1600 MPa.

[0065] The welding wire was further used to prepare the MAG weld metal. The welding current type was DCEP, the welding current was 240A, the arc voltage was 29V, the shielding gas was 95% Ar + 5% CO2, the gas flow rate during welding was 20L / min, and the interlayer temperature was less than 100°C. According to NB / T 47013.2-2015 "Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing", the weld metal was radiographically tested, and the test results were grade I and II. Figure 3 The various process properties of welding wire are shown in Table 1.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that in step (9), the welding wire passes through the oil tank filled with perfluoropolyether oil at a wire speed of 350 m / min. The remaining process steps and parameter settings are the same as those in Example 1.

[0068] The mechanical properties of the welding wire prepared in this comparative example were characterized, and the results showed that the tensile strength was 1400-1600 MPa.

[0069] The welding wire was further used to prepare the MAG weld metal. The welding current type was DCEP, the welding current was 240A, the arc voltage was 29V, the shielding gas was 95% Ar + 5% CO2, the gas flow rate during welding was 20L / min, and the interlayer temperature was less than 100°C. According to NB / T 47013.2-2015 "Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing", the weld metal was radiographically tested, and the test results were grade I and II. Figure 4 The various process properties of welding wire are shown in Table 1.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that the oil used in step (9) is water-soluble K3 oil with an oil concentration of 5%. The remaining process steps and parameter settings are the same as those in Example 1.

[0072] The mechanical properties of the welding wire prepared in this comparative example were characterized, and the results showed that the tensile strength was 1400-1600 MPa.

[0073] The welding wire was further used to prepare the MAG weld metal. The welding current type was DCEP, the welding current was 240A, the arc voltage was 29V, the shielding gas was 95% Ar + 5% CO2, the gas flow rate during welding was 20L / min, and the interlayer temperature was less than 100°C. According to NB / T 47013.2-2015 "Nondestructive Testing of Pressure Equipment Part 2: Radiographic Testing", the weld metal was radiographically tested, and the test results were grade I and II. Figure 5 The various process properties of welding wire are shown in Table 1.

[0074] Table 1

[0075]

[0076] From the above table 1 and Figure 1 to Figure 5 It can be seen that the martensitic stainless steel welding wires prepared in Examples 1 and 2 have excellent surface quality, small welding spatter, stable and powerful arc shape, good weld formation, and small porosity tendency of metal electrode gas shielded welding, and are very suitable for welding martensitic stainless steel turbine runners.

[0077] Moreover, the roller drawing process adopted in Example 1 reduces the use of wire drawing powder by 90% compared with the die drawing process of Comparative Example 1. In addition, Example 1 cooperates with the online cleaning process to avoid the residue of wire drawing powder on the surface of the welding wire, eliminating the adverse effect of wire drawing powder on welding stability. At the same time, compared with the immersion process of Comparative Example 2, the wire rope oiling process adopted in Example 1 does not reuse the oil to avoid oil pollution, and can accurately control the amount of oil applied on the surface of the welding wire, thereby improving welding stability. At the same time, compared with Comparative Example 3, Example 1 replaces the hydrocarbon chain oil with a fluorocarbon chain oil, thereby avoiding the effect of oiling on the weld porosity, and at the same time removes the moisture on the surface of the welding wire by drying, greatly reducing the porosity sensitivity of the welding.

[0078] Although the present invention has been disclosed as above in the preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a martensitic stainless steel welding wire, characterized in that: include: (1) Tempering: Tempering of martensitic stainless steel wire rod; (2) Pickling: Pickling is performed with a mixed acid obtained by mixing 6-8% H2SO4, 6-8% HCl and 2-4% HNO3, and the treatment time is 5 min; (3) Rough drawing: After tempering and pickling, the martensitic stainless steel wire rod is drawn through one roller to a 2.5 mm welding wire; (4) Bright annealing: The 2.5 mm welding wire obtained in (3) is subjected to bright annealing to obtain a wire material with a strength of 800 to 1200 MPa; (5) First fine drawing: 2.5 mm welding wire is drawn to 1.6 mm welding wire through one roller pass; (6) Electrolytic pickling: electrolytic pickling is carried out using H2SO4 solution; (7) Second fine drawing: The 1.6 mm welding wire is drawn by rollers once to a 1.4 mm welding wire, and then the 1.4 mm welding wire is drawn by linear drawing once to a 1.2 mm welding wire, and dry powdered fatty acid soap lubricant is used as drawing powder during the wire drawing process; (8) Online cleaning: Use steel wool dry wiping and steam cleaning to clean online; (9) Oiling: Apply perfluoropolyether oil on the surface of the welding wire by wire oiling method; (10) Drying, winding and packaging: The oiled welding wire is dried in a drying oven, then wound into a welding wire coil using a precision layer winding machine, and finally packaged using an automatic packaging machine.

2. The preparation method according to claim 1, characterized in that: (1) The tempering temperature is 600-620°C and the time is 1h.

3. The preparation method according to claim 1, characterized in that: (4) The medium bright annealing temperature is 800-850°C and the wire speed is 6-8 m / min.

4. The preparation method according to claim 1, characterized in that: (6) The concentration of H2SO4 solution is 16-20%, the electrolysis current is 15-25A, the length of the electrolyte acid tank is 20m, and the wire feeding speed is 100m / min.

5. The preparation method according to claim 1, characterized in that: (9) The oil coating parameters are: oil volume 0.1-0.3 mL / min, wire rope speed 6-12 cm / min, wire speed 300-350 m / min.

6. The preparation method according to claim 1, characterized in that: (10) The drying temperature is 300°C and kept at this temperature for 3 hours.

7. A martensitic stainless steel welding wire prepared by the method according to any one of claims 1 to 6.

8. An application of the martensitic stainless steel welding wire according to claim 7, characterized in that: For metal arc welding.

9. A welding method for Cr13Ni5 type martensitic stainless steel, characterized in that: The martensitic stainless steel welding wire according to claim 7 is used for welding by gas metal arc welding.

10. The welding method according to claim 9, characterized in that: The current type is DCEP, the welding current is 220-240A, the arc voltage is 28-30V, the shielding gas is composed of Ar and CO2 in a volume ratio of 95%:5%, the flow rate of the shielding gas is 18-20L / min, and the interlayer temperature is less than 100°C.

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