Welding wire, production method of welding wire and welding method of welding wire

Abstract

The invention discloses a welding wire, a production method of the welding wire and a welding method of the welding wire. The technical problem that the isometric crystallization degree of a Ti-free medium-chromium ferritic stainless steel welding seam structure is low is solved. The welding wire comprises the following chemical components in percentage by weight: less than or equal to 0.03% of C; 0.3 to 0.5 percent of Si; mn: 4.5 to 4.8%; p is less than or equal to 0.030%; s: 0.005% to 0.012%; cr: 17.5% to 18.5%; 1.1 to 1.5 percent of Ni; mo < = 0.75%; 0.21 to 0.55 percent of Ti; 0.11% to 0.18% of N; less than or equal to 0.02% of Al, and the balance Fe and inevitable impurities. The method can be suitable for the medium-chromium ferritic stainless steel welded pipe with the wall thickness not exceeding 2 mm and containing no Ti element, the purpose of improving the isometric crystallization degree of a weld joint structure is achieved by adding a small amount of welding wires, the weld joint is still a ferritic structure, the matching relation of the mechanical property and corrosion resistance of the weld joint and base metal is not affected, and meanwhile the production cost can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a welding wire, a production method of the welding wire and a welding method of the welding wire. Background Art

[0002] Ferritic stainless steel welded pipes are widely used in automobile exhaust systems and fluid fields. They are generally made by automated pipe production lines using argon arc welding or laser welding, and are all self-melting welding without adding welding wire. Since ferritic stainless steel does not undergo phase change in the entire temperature range, its self-melting weld structure is generally coarse columnar crystals and a small amount of equiaxed crystals in the central area, and the columnar crystals and equiaxed crystals grow in a competitive relationship when the weld solidifies.

[0003] In the early developed ferritic stainless steel, such as 430 stainless steel, the weld is almost entirely composed of columnar crystals that grow from the fusion line, which seriously reduces the plastic toughness of the weld. In order to increase the proportion of equiaxed crystals in the weld, Ti elements are added to ultra-pure ferritic stainless steel. These elements play a role in increasing the nucleation points during the solidification process of the weld to increase the proportion of equiaxed crystals in the center of the weld. However, even so, the proportion of equiaxed crystals in the weld of ultra-pure ferritic stainless steel generally does not exceed 20%.

[0004] In terms of grain refinement of welds, whether it is ferritic stainless steel, aluminum alloy or other metal materials, the main grain refinement technologies are as follows: controlling welding parameters, preheating and increasing cooling speed, adjusting molten pool alloy elements, pulse welding, electromagnetic stirring, laser stirring, platform mechanical vibration, ultrasonic assistance, etc. The main mechanisms for grain refinement are heterogeneous nucleation, promoting grain freedom, and dendrite melting.

[0005] For medium chromium ferritic stainless steel welded pipes that do not contain Ti, if the autogenous welding method is used, the autogenous weld structure is usually coarse columnar crystals. If the wire filling welding method is used, the filled welding wire contains both Ti and N. Since the N content in the welding wire in the prior art is unstable, the effect of using Ti-containing welding wire to make the weld structure of medium chromium ferritic stainless steel that does not contain Ti equiaxed crystallization is unstable. In addition, the Ni content in the existing welding wire is usually above 9%, and Ni does not contribute to the equiaxed crystallization of ferritic stainless steel welds. In addition, the price of Ni alloy is expensive, which affects the production cost and needs to be improved. Summary of the invention

[0006] In order to solve all or part of the above problems, the purpose of the present invention is to provide a welding wire, a production method of welding wire and a welding method of welding wire, which can improve the equiaxed crystallization degree of the weld structure of medium chromium ferrite stainless steel without Ti and reduce the production cost.

[0007] In a first aspect, the present invention provides a welding wire, and the chemical composition of the welding wire by weight percentage is: C ≤ 0.03%; Si: 0.3 - 0.5%; Mn: 4.5 - 4.8%; P ≤ 0.030%; S: 0.005 - 0.012%; Cr: 17.5 - 18.5%; Ni: 1.1 - 1.5%; Mo ≤ 0.75%; Ti: 0.21 - 0.55%; N: 0.11 - 0.18%; Al ≤ 0.02%, and the balance is Fe and unavoidable impurities.

[0008] Optionally, the metallographic structure of the welding wire air-cooled to room temperature contains austenite with a volume ratio of 11 - 18%, and the tissue composition is austenite + ferrite, or austenite + ferrite + martensite.

[0009] In a second aspect, the present invention provides a production method of a welding wire, including the following steps:

[0010] S1, smelting the raw materials to obtain an ingot;

[0011] S2, forging the ingot to obtain a bar;

[0012] S3, heat-treating the bar;

[0013] S4, rolling the heat-treated bar to obtain a wire rod;

[0014] S5, pickling the wire rod;

[0015] S6, cold-drawing the pickled wire rod to obtain a welding wire.

[0016] Optionally, in S1:

[0017] The raw materials are smelted by using vacuum induction melting + electroslag remelting, or vacuum induction melting + vacuum arc remelting.

[0018] Optionally, in S2:

[0019] Control the heating temperature of the ingot before forging to be 1170 - 1240 °C, the furnace residence time ≥ 10 hours, and control the starting forging temperature to be 1130 - 1200 °C and the final forging temperature ≥ 970 °C.

[0020] Optionally, in S3:

[0021] The bar is heated by a heating furnace, and control the heating temperature to be 1195 ± 20 °C and the heating time to be 2 - 4 hours.

[0022] Optionally, in S4:

[0023] The heat-treated bar is successively subjected to rough rolling, medium rolling, pre-finishing rolling, finishing rolling, and sizing rolling to obtain a prefabricated diameter size, and then coiled by a wire laying machine and collected. During the bar rolling process, the starting rolling temperature is controlled to be ≥1170°C and the finishing rolling temperature is controlled to be ≥970°C.

[0024] In a third aspect, the present invention provides a welding method for a welding wire, which is applied to a medium chromium ferritic stainless steel welded pipe with a wall thickness not exceeding 2 mm and without Ti. The welding method of the welding wire includes the following steps:

[0025] S1, controlling the volume ratio of the welding wire in the weld to be 19-21%;

[0026] S2, selecting the diameter of the welding wire, calculating the wire feeding speed of the welding wire according to the welding parameters, and ensuring that the wire feeding speed is 0.9-1.1 times the welding speed;

[0027] S3, welding the welding wire and the welded pipe through a welding device.

[0028] Optionally, in S2:

[0029] According to the formula:

[0030]

[0031] Calculate the wire feeding speed of the welding wire,

[0032] where: V 焊丝 is the volume of the welding wire added per minute, V 母材 is the volume of the base metal melted in the weld per minute, is the diameter of the welding wire, v 填 is the wire feeding speed, D 1 is the front width of the weld when the welded pipe is self-fused and welded, D 2 is the back width of the weld when the welded pipe is self-fused and welded, t is the wall thickness of the welded pipe, v 焊 is the welding speed of the welded pipe.

[0033] Optionally, in S3:

[0034] Controlling the filling welding angle to be 40°-60°, and controlling the hot wire current density to be 65-85 A / mm 2 .

[0035] From the above technical solutions, it can be seen that the welding wire, the production method of the welding wire, and the welding method of the welding wire provided by the present invention have the following advantages:

[0036] This welding wire is applicable to medium chromium ferritic stainless steel welded pipes with a wall thickness not exceeding 2 mm and without Ti element. Using existing welding equipment, without reducing the original welding efficiency of the welded pipe production line, by adding a small amount of welding wire, the purpose of improving the equiaxed crystal degree of the weld structure is achieved, and the weld is still ferritic structure, without affecting the mechanical property and corrosion resistance matching relationship between the weld and the base metal. At the same time, the content of Ni in this welding wire is low, thus reducing the production cost.

[0037] Other features and advantages of the present invention will be described in the subsequent specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings are used to provide a further understanding of the technical solution of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention, and do not constitute a limitation to the technical solution of the present invention.

[0039] Figure 1 is a flowchart of the production method of the welding wire in the embodiment of the present invention;

[0040] Figure 2 is a flowchart of the welding method of the welding wire in the embodiment of the present invention;

[0041] Figure 3 is a metallographic diagram of the weld after autogenous welding of medium chromium ferritic stainless steel TES18 without Ti in the embodiment of the present invention;

[0042] Figure 4 is a metallographic diagram of the weld after welding medium chromium ferritic stainless steel TES18 without Ti using the welding wire in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To make the purpose, technical solution and advantages of the present invention clearer and more understandable, the embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other arbitrarily.

[0044] Such as Figure 1 、 Figure 2 、 Figure 3 、 Figure 4The following is an embodiment of the present invention, which discloses a welding wire. The chemical composition of the welding wire by weight percentage is as follows: C ≤ 0.03%; Si: 0.3 - 0.5%; Mn: 4.5 - 4.8%; P ≤ 0.030%; S: 0.005 - 0.012%; Cr: 17.5 - 18.5%; Ni: 1.1 - 1.5%; Mo ≤ 0.75%; Ti: 0.21 - 0.55%; N: 0.11 - 0.18%; Al ≤ 0.02%, and the rest is Fe and inevitable impurities. At the same time, the metallographic structure of the welding wire air-cooled to room temperature contains austenite with a volume ratio of 11 - 18%, and the tissue composition is austenite + ferrite, or austenite + ferrite + martensite.

[0045] After long-term research on the welding of Ti-containing ultra-pure ferritic stainless steel, it is found that by using a hot wire TIG device to slightly fill the austenitic stainless steel welding wire, a large amount of equiaxed ferrite structure can be obtained in the weld. After a large number of targeted analyses and studies, it is found that the key factor for the equiaxial crystallization of the ultra-pure ferritic weld is the combination of N element in the austenitic stainless steel welding wire and Ti element in the ultra-pure ferritic stainless steel, forming a large amount of TiN particles to act as solidification nucleation points, increasing the proportion of equiaxed crystals in the weld.

[0046] In this application, the welding wire is applied to the welding of medium-chromium ferritic stainless steel without Ti. By adding a small amount to the weld, an almost fully equiaxed ferritic stainless steel weld can be obtained. As a carrier for adding Ti and N elements to the weld, the Ti content ranges from 0.21 - 0.55%, and the N content ranges from 0.11 - 0.18%. To ensure the smooth manufacture of the welding wire, a small amount of austenite structure is required to dissolve the N element, that is, a small amount of austenite-forming elements Ni and Mn need to be added.

[0047] For elements beneficial to corrosion resistance, they are implemented according to the design principles of conventional welding materials. The element S that affects the wettability of liquid metal is controlled between 0.005 and 0.012%, Si is controlled at about 0.5%, Al is controlled below 0.02%, and other elements are implemented with reference to the base metal standard.

[0048] In this embodiment, the chemical composition of the welding wire by weight percentage is preferably: C ≤ 0.014%; Si: 0.33 - 0.47%; Mn: 4.55 - 4.76%; P ≤ 0.030%; S: 0.007 - 0.011%; Cr: 17.65 - 18.35%; Ni: 1.15 - 1.43%; Mo ≤ 0.55%; Ti: 0.25 - 0.51%; N: 0.115 - 0.175%; Al ≤ 0.01%, and the rest is Fe and inevitable impurities.

[0049] The weld obtained by welding the medium chromium ferritic stainless steel TES18 without Ti using the welding wire in this embodiment has a ferritic structure, the proportion of equiaxed grains is ≥90%, the grain size in the equiaxed grain region is not lower than grade 5, the flaring rate is ≥40%, there are no intergranular corrosion cracks, and the pitting corrosion resistance is equivalent to that of the base metal.

[0050] As Figure 1 shown, this embodiment also discloses a production method of a welding wire for producing the above-mentioned welding wire. The production method of the welding wire includes the following steps:

[0051] S1, Use vacuum induction melting + electroslag remelting, or vacuum induction melting + vacuum arc remelting to smelt the raw materials to obtain an ingot.

[0052] S2, Forge the ingot to obtain a bar. Preferably, the bar is a round bar or a square bar. At the same time, control the heating temperature of the ingot before forging to be 1170 - 1240°C, the furnace residence time ≥10 hours, and control the starting forging temperature to be 1130 - 1200°C, and the final forging temperature ≥970°C.

[0053] S3, Heat-treat the bar, that is, heat the bar through a heating furnace, and control the heating temperature to be 1195 ± 20°C and the heating time to be 2 - 4 hours.

[0054] S4, The heat-treated bar is successively subjected to rough rolling, medium rolling, pre-finishing rolling, finishing rolling, and sizing rolling to obtain a prefabricated diameter size, and then coiled into a coil by a wire laying machine and collected to obtain a wire rod. At the same time, during the bar rolling process, control the starting rolling temperature ≥1170°C and the final rolling temperature ≥970°C.

[0055] S5, Pickle the wire rod to obtain a wire rod with a milky white surface.

[0056] S6, Cold-draw the pickled wire rod to obtain a special welding wire suitable for medium chromium ferritic stainless steel welded pipes without Ti.

[0057] As Figure 2 shown, this embodiment also discloses a welding method of a welding wire. Using the above-mentioned welding wire and applying it to a medium chromium ferritic stainless steel welded pipe with a wall thickness not exceeding 2 mm and without Ti, the welding method of the welding wire includes the following steps:

[0058] S1, In order to ensure good weld formation, in addition to the parameters of the automatic welding wire, it is also necessary to control the fusion ratio, that is, the volume ratio of the welding wire in the weld. Therefore, control the volume ratio of the welding wire in the weld to be 19 - 21%.

[0059] S2, Select the welding wire diameter, calculate the wire feeding speed of the welding wire according to the welding parameters, and ensure that the wire feeding speed is 0.9 - 1.1 times the welding speed.

[0060] In S3, the welding wire is welded to the welded pipe by a welding device.

[0061] In S2:

[0062] According to the formula:

[0063]

[0064] Calculate the wire filling speed of the welding wire,

[0065] where: V 焊丝 is the volume of the welding wire added per minute, V 母材 is the volume of the base material melted in the weld per minute, is the diameter of the welding wire, v 填 is the wire filling speed, D 1 is the front width of the weld when the welded pipe is self-fused and welded, D 2 is the back width of the weld when the welded pipe is self-fused and welded, t is the wall thickness of the welded pipe, v 焊 is the welding speed of the welded pipe.

[0066] In S3: The welded pipe is welded by using an automatic stainless steel TIG welding line. That is, a hot wire filling device is installed on the automatic stainless steel TIG welding line, and the welding wire in this application is added to the welding molten pool and mixed with the material to be welded, and a weld is formed after solidification. At the same time, during the welding process, the filling welding angle is controlled to be 40° - 60°, and the hot wire current density is controlled to be 65 - 85 A / mm 2 .

[0067] A large number of welding process tests show that when the wire filling speed v 填 is 0.9 - 1.1 times the welding speed, the process of adding the welding wire is continuous, without blasting, without spattering, without wire jamming, the weld surface is smooth and uniform, and the weld formation is good. Therefore, if the calculated wire filling speed is greater than or less than 0.9 - 1.1 times the welding speed, reselect the diameter of the welding wire and calculate the wire filling speed of the welding wire until the wire filling speed meets 0.9 - 1.1 times the welding speed.

[0068] A large number of welding process tests show that the hot wire current is selected according to the diameter of the welding wire, and the selection range of the hot wire current density (i.e., hot wire current / wire cross-sectional area) is 65 - 85 A / mm2. Too small a hot wire current will cause insufficient heat of the welding wire, absorb the arc heat when added to the molten pool, and increase the risk of incomplete penetration. Too large a hot wire current will cause the welding wire to explode and break during the short-circuit transfer with the molten pool, and the spatter from the explosion and break will contaminate the tungsten electrode, thereby increasing the frequency of stopping to replace the tungsten electrode.

[0069] In this embodiment, to adapt to the welding speed of over 1 m / min for automatic welded pipes, the way for the welding wire to enter the welding molten pool is stable short-circuit transition. That is, the area where the welding wire contacts the molten pool relies on the resistance heating of the hot wire current, and the tip of the welding wire melts and enters the welding molten pool in the way of dynamically stable bridging. This way depends on the hot wire TIG welding equipment.

[0070] Since the traditional TIG wire filling equipment does not have the function of heating the welding wire, the welding wire at room temperature is directly inserted into the welding molten pool and melts by the heat of the molten pool, which can be understood as ice entering water. This heating method is widely used in manual TIG welding. However, for automatic welded pipes with a wall thickness not exceeding 2 mm, in order to quickly melt the welding wire under the condition of a welding speed of over 1 m / min, it is necessary to increase the welding current, which will cause the phenomenon of burn-through when welding starts and no welding wire is added. The melted base metals on both sides cannot bridge to form a weld seam, and subsequent wire filling welding cannot be carried out.

[0071] The specific embodiments are as follows:

[0072] The raw materials are smelted by vacuum induction melting + electroslag remelting to obtain a 1-ton ingot. The ingot is heated at 1220 °C and then forged into bar stock by a radial forging machine. After being heated at 1200 °C, it is rolled into wire rods by a high-speed wire rod continuous rolling mill, and then prepared into and solid welding wires.

[0073] The weight percentages of chemical elements actually measured in Invention Examples 1-6 are shown in Table 1. The test steel plate is a 1-mm-thick Ti-free medium-chromium ferritic stainless steel TES18. Invention Examples 1-6 all adopt hot wire TIG welding. Through the calculation and derivation of the formulas in the above specific implementation manners, Invention Examples 1-6 all select welding wires. The welding processes are shown in Table 2, and the shielding gases in Invention Examples 1-6 are all argon with a purity of 99.999%. The comparative example adopts TIG autogenous welding, and the welding process is shown in Table 2.

[0074] Analyze the weld microstructure. The microstructure of the comparative example is all coarse columnar crystals (as Figure 3 described), the weld metal microstructures of Invention Examples 1-6 are similar and mainly consist of equiaxed crystals (as Figure 4 described), and the comparison of the equiaxed crystal ratio in the weld, the grain size in the equiaxed crystal region of the weld, the intergranular corrosion resistance, and the pitting corrosion resistance is shown in Table 3.

[0075] Among them, the grain size was measured according to the method for determining the average grain size of metals in GB / T 6394-2002, the intergranular corrosion performance was evaluated according to Method E in the test method for intergranular corrosion of stainless steels in metals and alloys in GB / T 4334-2008, and the pitting corrosion performance was evaluated according to the test method for pitting corrosion of stainless steels in ferric chloride in metals and alloys in GB / T 17897-2016.

[0076] By adding a small amount of the welding wire of the present invention to the weld, equiaxed grains of more than 90% were obtained in the weld of the medium chromium ferritic stainless steel TES18 without Ti. Compared with the autogenous TIG weld of the comparative example, the grain refinement effect was obvious, and there was no difference in the intergranular corrosion and pitting corrosion performance.

[0077] Table 1 Chemical compositions (weight percentages) of Invention Examples 1-6

[0078]

[0079]

[0080] Table 2 Welding process parameters

[0081] Welding current Welding speed Hot wire current density Filler wire feeding speed Shielding gas flow rate Comparative example 150A 1 m / min - - 8 L / min Inventive examples 1 - 6 150A 1 m / min <![CDATA[79.62 A / mm 2 > 1 m / min 8 L / min

[0082] Table 3 Weld microstructures and performance results of Invention Examples 1-6 and the comparative example

[0083] Serial number Proportion of equiaxed grains in the weld seam Grain size in the equiaxed grain region of the weld seam Intergranular corrosion result Pitting corrosion result Inventive example 1 95％ Grade 6.0 No crack Equivalent to the base metal Inventive example 2 92％ Grade 6.0 No crack Equivalent to the base metal Inventive example 3 95％ Grade 6.5 No crack Equivalent to the base metal Inventive example 4 95％ Grade 6.5 No crack Equivalent to the base metal Inventive example 5 91％ Grade 6.0 No crack Equivalent to the base metal Inventive example 6 94％ Grade 6.0 No crack Equivalent to the base metal Comparative example 0％ - No crack Equivalent to the base metal

[0084] As can be seen from the above, the present application can increase the proportion of equiaxed grains in the weld of the medium chromium ferritic stainless steel without Ti from 20% of the traditional weld to more than 90%. The weld microstructure changes from the traditional one dominated by coarse columnar grains to the one dominated by equiaxed grains. The overall grain size is significantly refined. The weld microstructure is still ferritic, which does not affect the matching relationship between the mechanical properties and corrosion resistance of the weld and the base metal. At the same time, the grain size in the equiaxed grain region is not lower than Grade 5, the flaring rate ≥ 40%, there are no intergranular corrosion cracks, and the pitting corrosion resistance is equivalent to that of the base metal.

[0085] Moreover, compared with the existing Ti-containing austenitic stainless steel welding wire ER321, the welding wire in the present application has a stable equiaxed grain effect on the weld, low alloy cost, saves about 8% of Ni element, and reduces the alloy cost of each ton of welding wire by more than one thousand yuan, having great economic benefits. At the same time, considering the lack of nickel resources in China and the frequent fluctuations of international nickel prices, the welding wire proposed by the present invention also has great social benefits and significance.

[0086] It should be noted that unless otherwise specified, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0087] Furthermore, terms such as "first", "second", etc. are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. In the description of the present invention, "a plurality of" means more than two unless otherwise specifically defined.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A welding wire, characterized in that: The chemical composition weight percentage of the welding wire is: C≤0.03%; Si: 0.3-0.5%; Mn: 4.5-4.8%; P≤0.030%; S: 0.005-0.012%; Cr: 17.5-18.5%; Ni: 1.1-1.5%; Mo≤0.75%; Ti: 0.21-0.55%; N: 0.11-0.18%; Al≤0.02%, the rest is Fe and unavoidable impurities.

2. The welding wire according to claim 1, characterized in that The metallographic structure of the welding wire after air cooling to room temperature contains 11-18% austenite by volume, and the structure is austenite + ferrite, or austenite + ferrite + martensite.

3. A method for producing a welding wire, used for producing the welding wire according to claim 1 or 2, characterized in that: The production method of welding wire comprises the following steps: S1, smelting the raw materials to obtain an ingot; S2, forging the ingot to obtain a rod; S3, heat treating the rod; S4, rolling the heat-treated bar to obtain a wire; S5, pickling the wire; S6, cold drawing the pickled wire to obtain welding wire.

4. The method for producing welding wire according to claim 3, characterized in that: In S1: The raw materials are smelted by vacuum induction melting + electroslag remelting, or vacuum induction melting + vacuum arc remelting.

5. The method for producing welding wire according to claim 3, characterized in that: In S2: The heating temperature of the ingot before forging is controlled to be 1170-1240℃, the residence time is ≥10 hours, the start forging temperature is controlled to be 1130-1200℃, and the final forging temperature is ≥970℃.

6. The method for producing welding wire according to claim 3, characterized in that: In S3: The rod is heated by a heating furnace, and the heating temperature is controlled to be 1195±20°C and the heating time is 2-4 hours.

7. The method for producing welding wire according to claim 3, characterized in that: In S4: The heat-treated bars are sequentially rough rolled, intermediate rolled, pre-finished rolled, finished rolled and reduced-sizing rolled to obtain the prefabricated diameter size, and then coiled on the laying machine and collected. During the bar rolling process, the start rolling temperature is controlled to be ≥1170℃ and the final rolling temperature is controlled to be ≥970℃.

8. A welding method using a welding wire, using the welding wire according to claim 1 or 2, characterized in that: Applicable to medium chromium ferrite stainless steel welded pipe with a wall thickness not exceeding 2 mm and containing no Ti, the welding method of the welding wire includes the following steps: S1, control the volume ratio of welding wire to weld to be 19-21%; S2, select the wire diameter, calculate the wire filling speed according to the welding parameters, and ensure that the wire filling speed is 0.9-1.1 times the welding speed; S3, welding the welding wire and the welding pipe by means of welding equipment.

9. The welding method of welding wire according to claim 8, characterized in that: In S2: According to the formula: Calculate the wire filling speed, Where: V 焊丝 is the volume of welding wire added per minute, V 母材 is the volume of base material melted in the weld per minute, is the wire diameter, v 填 is the wire filling speed, D1 is the front width of the weld during autogenous welding of the welded pipe, D2 is the back width of the weld during autogenous welding of the welded pipe, t is the wall thickness of the welded pipe, v 焊 is the welding speed of the welded pipe.

10. The welding method of welding wire according to claim 8, characterized in that: In S3: Control the fill welding angle to 40°-60° and the hot wire current density to 65-85A / mm 2 .

Images