A flux and soldering method

Abstract

The application discloses a flux and a welding method, and solves the technical problems of large smoke and many pores in the welding process of a zinc-based plated sheet. The flux is composed of the following components in percentage by mass: CaF2: 5-20%; SiO2: 15-45%; a gas forming agent: 10-20%; Al2O3: less than or equal to 10%; MgO+CaO: less than or equal to 15%; TiO2: less than or equal to 10%; MnO: less than or equal to 35%, and the rest is inevitable impurities. After the workpiece is welded by using the flux, the weld is well formed, the surface is free of pores, the weld pore rate is 0-2%, the spatter rate is 0, the fracture position is the base material, and the weld strength is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding, and particularly relates to a flux and a welding method. BACKGROUND

[0002] The failure and scrap of steel materials caused by corrosion are huge every year, which not only causes huge economic losses, but also does not conform to the concept of green environmental protection and sustainable development of steel materials. After the surface of the steel plate is treated by galvanizing, the service life of the steel plate can be greatly improved. It is widely used in construction, automobile, steel plate warehouse, photovoltaic support, highway guardrail, agricultural machinery and other industries.

[0003] In the prior art, zinc-based plated steel plate welding usually adopts gas metal arc welding, and inert gas is used as protective gas for welding. Since the boiling point of zinc in the zinc-based plated layer is 907 degrees, the temperature required for steel plate welding is above 1500 DEG C, and when the base material steel plate has not reached the melting state, the zinc layer has begun to vaporize and evaporate, and the white smoke mainly composed of zinc oxide is emitted during welding, which can damage the respiratory tract, digestive tract, nervous system and reproductive system of the human body. At the same time, during the melting welding process, the zinc vapor escaping from the molten pool will cause porosity defects.

[0004] Therefore, it is urgent to improve the working environment of the operating personnel and the quality of the weld. SUMMARY

[0005] In order to solve the technical problems of poor working environment and many pores in the welding process of zinc-based plated steel plate, the application provides a flux and a welding method.

[0006] In the first aspect of the application, a flux is provided, which is used for welding first and second workpieces each comprising a body and a zinc-based plated layer covering the body, and consists of the following components in mass percentage:

[0007] CaF2: 5%-20%;

[0008] SiO2: 15%-45%;

[0009] Gas forming agent: 10%-20%;

[0010] Al2O3: less than or equal to 10%;

[0011] MgO+CaO: less than or equal to 15%;

[0012] TiO2: less than or equal to 10%;

[0013] MnO: less than or equal to 35%;

[0014] The rest is inevitable impurities.

[0015] In some embodiments, the gas forming agent is at least one of K2CO3, Na2CO3, CaCO3, NaHCO3, and KHCO3.

[0016] In some embodiments, the mass percentage ratio between CaF2 and the gas forming agent is 0.4-5.

[0017] In some embodiments, the mass percentage of CaF2 is 10-15%, the mass percentage of SiO2 is 20-40%, and the mass percentage of the gas forming agent is 12-18%.

[0018] In some embodiments, the particle size of the flux is 8-80 mesh.

[0019] In the second aspect of the present application, a welding method is provided, comprising:

[0020] Step 1, setting the gap of the to-be-welded part of the first workpiece and the second workpiece, both of which include a zinc-based plating layer, to form a to-be-welded area;

[0021] Step 2, laying the flux on the to-be-welded area of the first workpiece and the second workpiece and then welding.

[0022] In some embodiments, in the case of butt welding of the first workpiece and the second workpiece in step 2, the laying thickness of the flux is 2mm-500mm, and the size of the flux perpendicular to the extension direction of the butt joint gap is not less than 2mm.

[0023] In some embodiments, the welding of step 2 is single-pass arc welding, the welding current is ≤350A, the welding voltage is 6-38V, the welding speed is 4-30mm / s, and the wire feeding speed is 1-13m / min; the diameter of the welding wire used for welding is 0.5-2mm.

[0024] In some embodiments, in step 2, the welding specifically includes: controlling the welding current to be 60-300A, the welding voltage to be 8-35V, the welding speed to be 5-20mm / s, and the wire feeding speed to be 2-12m / min, and the welding is single-pass welding.

[0025] In some embodiments, in step 1, the butt joint gap of the to-be-welded part of the first workpiece and the second workpiece is 0.1mm-3mm.

[0026] In some embodiments, the thickness of the substrate of the first workpiece and the second workpiece is both 0.5-6.5nmm, and the thickness of the zinc-based plating layer of the first workpiece and the second workpiece is both 70g / ㎡-1200g / ㎡.

[0027] In some embodiments, the welding is single-pass welding, and the welding is completed at one time.

[0028] The flux provided by the embodiment of the application comprises the following components in percentage by mass: CaF2: 5%-20%; SiO2: 15%-45%; gas generator: 10%-20%; Al2O3≤10%; MgO+CaO≤15%; TiO2≤10%; MnO≤35%, wherein the F element ionized from CaF2 combines with the Zn element in the workpiece coating to form ZnF2, which is deposited in the welding slag, thereby reducing the content of Zn vapor in the environment; SiO2 can increase the fluidity of the molten pool, adjust the solidification point and surface tension of the slag, promote the escape of most of the Zn vapor when the molten pool is in a liquid state, and reduce the amount of Zn vapor escaping during the solidification stage of the molten pool, thereby improving the porosity defect of the weld; the gas generator can protect the molten pool, and the decomposed gas can also form a local high gas pressure in the molten pool to promote overflow of the molten pool; Al2O3 can adjust the viscosity of the molten slag to ensure the smoothness and fluidity of the weld surface.

[0029] The application adds CaF2, SiO2, a gas generator and Al2O3, wherein the Ca element ionized from CaF2 combines with the O element in the air to form CaO, the CaO, SiO2 and Al2O3 formed can reduce the viscosity and melting point of the molten slag, improve the fluidity of the molten pool, promote the escape of a large amount of Zn vapor when the molten pool is in a liquid state with good fluidity, reduce the escape amount during the solidification stage of the molten pool, and reduce the porosity defect of the weld; the F element ionized from CaF2 combines with the escaped Zn vapor to form solid ZnF2 and is deposited in the welding slag, thereby reducing the content of Zn vapor in the environment and improving the working environment of the welder.

[0030] The workpiece welded by using the flux of the application has a well-shaped weld, no porosity on the surface, a porosity rate of 0%-2% for the weld, a spatter rate of 0, a fracture position of the base material, and a high weld strength. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is an X-ray detection photograph of the weld after welding of the two steel plates in Example 1 of the application;

[0032] Figure 2 It is an X-ray detection photograph of the weld after welding of the two steel plates in Comparative Example 1 of the application. DETAILED DESCRIPTION

[0033] In order to make the skilled in the art to which the present application belongs more clearly understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0034] In the first aspect of the present application, a flux is provided for welding first and second workpieces each comprising a body and a zinc-based coating layer covering the body, such as welding two steel plates each having a zinc coating layer, to improve the working environment of welders and reduce porosity and spatter of the weld.

[0035] The flux provided by the embodiments of the present application consists of the following components by mass percentage:

[0036] CaF2: 5%-20%;

[0037] SiO2: 15%-45%;

[0038] Gas forming agent: 10%-20%;

[0039] Al2O3≤10%;

[0040] MgO+CaO≤15%;

[0041] TiO2≤10%;

[0042] MnO≤35%;

[0043] The rest is inevitable impurities.

[0044] The functions of the components are described as follows:

[0045] CaF2: Under high-temperature welding conditions, the ionized F element of CaF2 combines with the escaped Zn vapor in the coating layer of the workpiece at the weld to form solid ZnF2 and deposit in the slag, thereby reducing the content of Zn vapor in the environment and ensuring the working environment of the welder. The ionized Ca element of CaF2 combines with the O element in the air to form CaO, which can further reduce the viscosity and melting point of the slag and improve the fluidity of the molten pool, so that most of the Zn vapor escapes when the molten pool is in a liquid state, and only a small amount of Zn vapor escapes during the solidification process of the molten pool, thereby reducing the porosity defects of the weld; if the content of CaF2 is too low, the dezincification and solidification effects are not significant; if the content of CaF2 is too high, the deslagging effect is affected;

[0046] SiO2: SiO2 is an acidic substance that is deoxidized during welding to introduce Si into the molten pool, thereby improving its fluidity. This allows most of the Zn vapor to escape from the molten pool to the surface while it is still in a liquid state, where it reacts chemically with the F2 ionized from CaF2 and deposits in the weld slag in solid form. If the SiO2 content is too low, the effect of increasing the fluidity of the molten pool is not significant, and it may increase porosity defects to some extent. If the SiO2 content is too high, it is easy to form inclusions and other defects inside the weld, affecting the welding quality.

[0047] Gas-generating agent: During welding, the gas-generating agent decomposes into gas to protect the molten pool. At the same time, the decomposed gas can also form a local high pressure in the weld pool, promoting the overflow of Zn vapor from the molten pool.

[0048] Al2O3: An amphoteric oxide. Since the welding object is galvanized sheet, Zn element affects the arc stability, and the reaction in the molten pool is very intense during welding. Adding Al2O3 can increase the surface tension of the slag, reduce the viscosity of the slag, ensure the smoothness and fluidity of the weld surface, and promote the removal of Zn vapor from the molten pool. If the Al2O3 content is too low, the effect of increasing the fluidity of the molten pool is not significant, and it will reduce the zinc removal rate to some extent; if the Al2O3 content is too high, the Al element in the weld will be too high, forming high-temperature ferrite, which will affect the strength and toughness of the weld.

[0049] MgO+CaO: MgO and CaO are strong alkaline substances and excellent slag-forming materials, which reduce the particle size of welding slag in order to control the shape of the weld.

[0050] TiO2: TiO2 is an acidic oxide that can improve the physical properties of slag, turn long slag into short slag, make the slag on the weld surface change quickly with temperature, and make it easy to detach, thus increasing slag removal. Ti is dispersed in the weld in the form of micro-particle oxides (TiO) or (TiC), which promotes the refinement of weld metal grains and improves the impact toughness at ultra-low temperatures.

[0051] MnO ≤ 35%; MnO can introduce Mn into the weld, improving its strength and impact toughness, while simultaneously reducing S content and decreasing crack formation. In some embodiments, MnO ≥ 10%.

[0052] In some embodiments, the gas-forming agent is at least one of K2CO3, Na2CO3, CaCO3, NaHCO3 and KHCO3. The gas-forming agent is a salt containing carbonate or bicarbonate, which can decompose carbon dioxide gas at high temperature welding, and the carbon dioxide gas can form a local high pressure in the welding pool to promote the escape of Zn vapor, and the carbon dioxide gas can also decompose to produce oxygen, which oxidizes the zinc vapor and the zinc not converted into zinc vapor into zinc oxide powder and fixes it in the welding slag. At the same time, K and Na have strong ionization ability and can stabilize the arc.

[0053] In some embodiments, the mass percentage ratio between CaF2 and the gas-forming agent is 0.4-5.

[0054] In some embodiments, the mass percentage of CaF2 is 10-15%, the mass percentage of SiO2 is 20-40%, and the mass percentage of the gas-forming agent is 12-18%.

[0055] In some embodiments, the particle size of the flux is 8-80 mesh.

[0056] In the second aspect of the present application, a welding method is provided, which uses the flux of any one of the embodiments of the first aspect to weld, improve the working environment of the welder, and reduce the porosity of the weld and spatter.

[0057] The welding method comprises the following steps:

[0058] Step 1: setting the gap of the to-be-welded part of the first workpiece and the second workpiece each comprising a zinc-based plating layer to form a to-be-welded area; wherein the gap can be 0.1 mm-3 mm, and the weld of the first workpiece and the second workpiece can use butt joint, lap joint and corner joint gap pre-setting:

[0059] Step 2: laying the flux on the to-be-welded area of the first workpiece and the second workpiece and then welding.

[0060] The flux is covered on the welding area, heated by the arc heat generated between the welding wire and the base plate of the steel plate, and the molten pool is covered in the gas atmosphere generated by the particulate matter. After the weld is solidified, the welding slag covered on the surface of the weld is removed to obtain a steel part with a zinc or zinc-based alloy plating layer.

[0061] Before welding, the first workpiece and the second workpiece to be welded are subjected to surface treatment by physical or chemical methods to remove oil stains, moisture and rust from the to-be-welded area. The first workpiece and the second workpiece can each be a steel plate comprising a base body and a zinc or zinc-based alloy plating layer on at least one surface thereof. The plating layer of the steel plate to be welded is not removed, thinned or preheated.

[0062] The yield strength of the steel plate to be welded is 235-1300 MPa, and the substrate thickness is 0.5 mm-6 mm. The composition of the steel plate to be welded can consist of the following components: C: 0.06-0.15%, Si: 0.4-1.2%, Mn: 1-2.2%, P+S≤0.05%, Ni+Cr+Mo+V≤0.6%, Ti+Zr+Al: 0-0.45%, Cu: 0.1-0.5%, and the rest is Fe and other unavoidable impurities.

[0063] In some embodiments, in the case of butt welding of the first workpiece and the second workpiece in step 2, the laying thickness of the flux is 2 mm-500 mm, and the size of the flux perpendicular to the extension direction of the butt joint gap is not less than 2 mm, that is, the laying width of the flux is not less than 2 mm. If the laying width of the flux is too small, the protection effect is poor. If the laying thickness of the flux is too thick, it will affect the movement of the welding wire, causing deviation and affecting the welding quality.

[0064] In some embodiments, the welding of step 2 is single-pass arc welding, the welding current is ≤350 A, the welding voltage is 6-38 V, the welding speed is 4-30 mm / s, and the wire feeding speed is 1-13 m / min; the diameter of the welding wire used for welding is 0.5-2 mm.

[0065] In some embodiments, in step 2, the welding specifically includes: controlling the welding current to be 60-300 A, the welding voltage to be 8-35 V, the welding speed to be 5-20 mm / s, and the wire feeding speed to be 2-12 m / min, and the welding is single-pass welding. If the welding current, welding voltage, welding speed and wire feeding speed are too large, it is easy to burn through the substrate, and at the same time, more plating layers near the weld are volatilized, reducing the corrosion resistance of the weld. If the process data is too low, the weld will not be formed, affecting the joint strength.

[0066] In some embodiments, in step 1, the butt joint gap of the first workpiece and the second workpiece to be welded is 0.1 mm-3 mm.

[0067] In some embodiments, the substrate thickness of the first workpiece and the second workpiece is 0.5-6.5 nmm, and the thickness of the zinc-based plating layer of the first workpiece and the second workpiece is 70 g / m2-1200 g / m2.

[0068] In some embodiments, the welding is single-pass welding, and the welding is completed at one time.

[0069] The welding can be performed by a welding gun with a walking mechanism, which can make the welding gun walk along a fixed track, such as a robot, a five-axis manipulator, or a welding trolley. The flux can be pre-laid on the welding area, or can cover the area to be welded during welding. A flux recovery device can be added behind the welding gun.

[0070] The flux and the welding method provided in the present application will be further described below in combination with specific examples.

[0071] Examples 1 to 7 and Comparative Examples 1 to 6

[0072] Examples 1 to 7 and Comparative Examples 1 to 6

[0073] Step 1, butt joint the two steel plates to be welded, which both include a zinc-based plating layer;

[0074] Step 2, lay the flux on the butt joint area of the two steel plates and then weld.

[0075] The material, thickness, plating layer composition, plating layer thickness, and base material structure of the two steel plates can be referred to Table 1. The welding wire composition can be referred to Table 2, and the rest is unavoidable impurities. The flux composition can be referred to Table 3, and the rest is unavoidable impurities. In Examples 1 to 5, the gas generator is a mixture of K2CO3, Na2CO3, and CaCO3. In Examples 6 to 7, the gas generator is a mixture of NaHCO3 and KHCO3. The welding process can be referred to Table 4. The welding results can be referred to Table 5. In Example 7, the welding wire is an ER50-6 welding wire.

[0076] Comparative Examples 7 to 12

[0077] Comparative Examples 7 to 12, the first workpiece and the second workpiece are welded by gas shielded arc welding, and 20% CO2+80% Ar is used for gas protection, and the gas flow is 10-25 L / min. Comparative Examples 1 to 6 provide a welding method, which includes the following steps:

[0078] Step 1, butt joint the two steel plates to be welded, which both include a zinc-based plating layer;

[0079] Step 2, lay the flux on the butt joint area of the two steel plates and then weld.

[0080] The material, thickness, plating layer component, plating layer thickness and base material structure of the first workpiece and the second workpiece can refer to Table 1; the welding wire is ER50-6 welding wire, and the composition can refer to Table 2, and in addition to the components given in Table 2, the rest is Fe and inevitable impurities; the composition of the flux can refer to Table 3, and the rest is inevitable impurities; the welding process can refer to Table 4; and the welding result can refer to Table 5.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085]

[0086] Table 3

[0087] No. CaF2 SiO2 Gas forming agent Al2O3 MgO + CaO TiO2 MnO Example 1 10％ 35％ 10％ 5％ 10％ 5％ 24％ Example 2 15％ 25％ 20％ 10％ 5％ 5％ 18％ Example 3 15％ 15％ 10％ 5％ 10％ 10％ 34％ Example 4 9％ 15％ 16％ 7％ 15％ 10％ 25％ Example 5 20％ 15％ 15％ 5％ 10％ 10％ 24％ Example 6 8％ 38％ 15％ 5％ 10％ 10％ 12％ Example 7 12％ 24％ 12％ 5％ 10％ 5％ 30％ Comparative Example 1 4％ 38％ 10％ 5％ 10％ 8％ 24％ Comparative Example 2 25％ 29％ 10％ 5％ 10％ 10％ 10％ Comparative Example 3 10％ 10％ 20％ 10％ 10％ 10％ 29％ Comparative Example 4 10％ 50％ 10％ 5％ 10％ 4％ 10％ Comparative Example 5 10％ 38％ 5％ 10％ 10％ 10％ 15％ Comparative Example 6 10％ 29％ 30％ 5％ 10％ 5％ 10％

[0088] Table 4

[0089]

[0090]

[0091] Table 5

[0092] No. Weld appearance Surface porosity Porosity of weld bead Spatter rate Fracture position Example 1 Good None 2％ 0 Base material Example 2 Good None 0％ 0 Base material Example 3 Good None 1％ 0 Base material Example 4 Good None 0.50％ 0 Base material Example 5 Good None 1.50％ 0 Base material Example 6 Good None 2％ 0 Base material Example 7 Good None 0％ 0 Base material Comparative Example 1 Poor Yes 35％ 3.5 g / 100 mm Weld Comparative Example 2 Poor Yes 20％ 1.2 g / 100 mm Weld Comparative Example 3 Poor Yes 50％ 4.2 g / 100 mm Weld Comparative Example 4 Poor Yes 12％ 2.4 g / 100 mm Weld Comparative Example 5 Poor Yes 80％ 6.8 g / 100 mm Weld Comparative Example 6 Poor Yes 70％ 8 g / 100 mm Weld Comparative Example 7 Poor Yes 50％ 3.2 g / 100 mm Weld Comparative Example 8 Poor Yes 60％ 2.8 g / 100 mm Weld Comparative Example 9 Poor Yes 30％ 5 g / 100 mm Weld Comparative Example 10 Poor Yes 45％ 2.2 g / 100 mm Weld Comparative Example 11 Poor Yes 20％ 4 g / 100 mm Weld Comparative Example 12 Poor Yes 15％ 1.8 g / 100 mm Weld

[0093] Table 5 is a welding result statistical table, wherein the weld forming is the surface quality of the weld observed by naked eyes, if the weld is rough, uneven, irregular, the weld and the base material are not smooth, the welding joint is poor, and the weld is uneven, then the weld forming is poor; the surface porosity is the porosity and formability of the weld area observed by naked eyes; the weld porosity rate is the influence of gas on the weld during the welding process, the higher the weld porosity rate, the worse the strength of the weld; the spatter rate is the spatter rate of the slag, the higher the spatter rate, the worse the surface quality of the weld; and the fracture position is the lowest strength position of the welded workpiece.

[0094] According to the data in Table 5, the workpiece welded by using the flux and the welding method provided in embodiments 1 to 7 has good weld forming, no surface porosity, a weld porosity rate of 0% to 2%, a spatter rate of 0, a fracture position of the base material, and high weld strength.

[0095] Figure 1 The flaw detection photos of the weld formed by using the flux and the welding method provided in embodiment 1 under X-ray can be seen from Figure 1, and it can be seen that the internal porosity (black dots) is very small, and the porosity rate is low.

[0096] Using the flux and welding method of Comparative Example 1, the flux with too low CaF2 content resulted in poor weld formation and surface quality after welding the workpiece; the weld porosity was 35%, leading to poor weld strength; the spatter rate was 3.5 g / 100 mm, indicating poor weld surface quality; and the weld had surface porosity, resulting in low weld surface quality. Figure 2 The image 2 shows the X-ray flaw detection of the weld bead formed using the method provided in Comparative Example 1. As can be seen from Figure 2, there are a great many pores (black dots) inside, indicating a high porosity.

[0097] Using the flux and welding method of Comparative Example 2, the flux with excessive CaF2 resulted in poor weld formation and surface quality after welding; the weld porosity was 20%, leading to poor weld strength; the spatter rate was 1.2 g / 100 mm, indicating poor weld surface quality; and the weld had surface porosity, resulting in low weld surface quality.

[0098] Using the flux and welding method of Comparative Example 3, the flux with too low SiO2 resulted in poor weld formation and poor weld surface quality after welding the workpiece; the weld porosity was 50%, resulting in poor weld strength; the spatter rate was 4.2 g / 100 mm, resulting in poor weld surface quality; and the weld had surface porosity, indicating low weld surface quality.

[0099] Using the flux and welding method of Comparative Example 4, the flux with excessive SiO2 resulted in poor weld formation and surface quality after welding; the weld porosity was 12%, leading to poor weld strength; the spatter rate was 2.4 g / 100 mm, indicating poor weld surface quality; and the weld had surface porosity, resulting in low weld surface quality.

[0100] Using the flux and welding method of Comparative Example 5, the flux with too low carbonate content resulted in poor weld formation and poor weld surface quality after welding the workpiece; the spatter rate was 6.8 g / 100 mm, indicating poor weld surface quality; the weld also had surface porosity, indicating low weld surface quality.

[0101] Using the flux and welding method of Comparative Example 6, the flux with excessive carbonate content resulted in poor weld formation and surface quality after welding; the weld porosity was 80%, resulting in poor weld strength; the weld porosity was 70%, resulting in poor weld strength; the spatter rate was 8g / 100mm, resulting in poor weld surface quality; and the weld had surface porosity, resulting in low weld surface quality.

[0102] After the welding of the melting electrode gas shield welding of the comparative example 7 to the comparative example 12, the weld forming is poor, and the surface quality of the weld is reduced. The porosity of the weld is 12% to 80%, and the strength of the weld is low. The spatter rate of the welding is 1.2g / 100mm to 8g / 100mm, and the surface quality of the weld is low. The fracture position is the weld, that is, the strength of the weld is low, and the weld is easy to break. The weld has surface porosity, and the surface quality of the weld is low.

[0103] Compared with the flux consisting of CaF2: 5%-20%; SiO2: 15%-45%; gas forming agent: 10%-20%; Al2O3≤10%; MgO+CaO≤15%; TiO2≤10%; MnO≤35% by mass percentage, if the content of CaF2 is too low, the dezincification and solidification of zinc are not significant; if the content of CaF2 is too high, the deslagging effect is affected;

[0104] If the content of SiO2 is too low, the effect of increasing the fluidity of the molten pool is not significant; if the content of SiO2 is too high, the inclusion and other defects are easily formed in the weld, and the welding quality is affected; if the proportion of the carbonate is too low, the welding molten pool is affected; if the proportion of the carbonate is too high, CO pores are generated, and the surface quality of the weld is affected.

[0105] The flux of the present application sets CaF2, the ionized Ca can combine with oxygen in the air to form CaO which reduces the viscosity and melting point of the slag, promotes dezincification, the ionized F combines with the Zn element in the plating layer of the workpiece to form ZnF2, reduces the concentration of Zn in the environment, and improves the working environment; SiO2 can increase the fluidity of the molten pool, adjust the solidification point and surface tension of the slag, and promote the escape of Zn vapor; the gas forming agent can decompose carbon dioxide gas to protect the molten pool, form a local high pressure, promote dezincification, and the decomposed carbon dioxide gas forms oxygen through chemical reaction, the oxygen can oxidize the zinc vapor and the zinc which has not formed zinc vapor to zinc oxide powder and fix it in the welding slag, and further rapidly reduce the zinc vapor in the environment.

[0106] In summary, the application uses SiO2 and CaF2 to improve the fluidity of the molten pool to promote the emission of a large amount of Zn vapor; the large amount of Zn vapor combines with ionized F in CaF2 to form ZnF2 and combines with oxygen formed after the chemical reaction of the gas-making agent to form ZnO, both of which are deposited in the welding slag in a solid state, thereby rapidly reducing the Zn vapor in the environment. Due to the good fluidity of the molten pool, most of the Zn vapor is excluded in the liquid phase, and only a small amount is excluded in the solidification stage of the molten pool, thereby reducing the porosity of the weld. The flux and welding method of the application solve the technical problems of large smoke, many pores, and many spatters in the welding process of zinc-based plated sheet, increase the surface quality of the weld, and increase the weld strength. After welding with the flux of the application, the weld is well formed, the surface is free of pores, the weld porosity is 0% to 2%, the spatter rate is 0, the fracture position is the base material, and the weld strength is high.

[0107] The application has at least the following advantages:

[0108] (1) The welding process is stable, and welding defects such as welding spatter and welding undercut are significantly reduced, and the welding gun nozzle and the base plate welding spatter do not need to be cleaned after welding;

[0109] (2) The application can promote the escape of zinc vapor from the molten pool, significantly reduce the welding porosity, and improve the mechanical properties and fatigue properties of the welded joint;

[0110] (3) The thickness of the oxide layer on the weld surface is reduced by more than 80% compared with the conventional welding process, which can improve the adhesion of the weld spray and electrophoresis and improve the protection level;

[0111] (4) The burn loss area of the plating layer is small, and the plating elements are enriched in the transition area between the heat-affected zone and the weld, thereby improving the corrosion resistance of the welded joint.

[0112] (5) The welding process has less Zn vapor in the environment, is environmentally friendly, and can protect the health of the operator.

[0113] In the application, unless otherwise explicitly specified and limited, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "above" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Below", "below" and "below" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0114] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0115] In the present application, unless otherwise expressly specified and limited, the terms "connection", "fixation" and the like should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0116] In addition, in the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise expressly specified and limited.

[0117] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A flux for welding a first workpiece and a second workpiece, both comprising a body and a zinc-based plating covering the body, characterized in that, The flux is composed of the following components by mass percentage: CaF2: 5%-15%; SiO2: 15%-45%; Gas-generating agent: 10%-12%; the gas-generating agent is at least one selected from K2CO3, Na2CO3, CaCO3, NaHCO3 and KHCO3; Al2O3≤10%; MgO+CaO≤15%; TiO2 ≤ 10%; MnO≤35%; The remainder are unavoidable impurities; The welding method using the flux includes: Step 1: Set a gap between the first and second workpieces, both of which have zinc-based coatings, to form a welding area; Step 2: Apply flux to the welding areas of the first and second workpieces and then weld; the flux thickness is 2mm-500mm, and the dimension of the flux perpendicular to the extension direction of the butt joint gap is not less than 2mm.

2. The flux as described in claim 1, characterized in that, The mass percentage ratio between CaF2 and the gasifying agent is 0.4~5.

3. The flux as described in claim 1, characterized in that, The mass percentage of CaF2 is 10-15%, and the mass percentage of SiO2 is 20-40%.

4. The flux according to any one of claims 1 to 3, characterized in that, The flux has a particle size of 8-80 mesh.

5. The flux according to any one of claims 1 to 3, characterized in that, The welding in step 2 is a single-pass welding, with a welding current ≤350A, a welding voltage of 6-38V, a welding speed of 4-30mm / s, a wire feeding speed of 1-13m / min, and a welding wire diameter of 0.5-2mm.

6. The flux according to claim 5, characterized in that, In step 2, the welding current is 60-300A, the welding voltage is 8-35V, the welding speed is 5-20mm / s, the wire feeding speed is 2-12m / min, and the welding is a single-pass welding.

7. The flux according to any one of claims 1 to 3, characterized in that, In step 1, the gap between the welded joints of the first workpiece and the second workpiece is 0.1mm-3mm, the substrate thickness of the first workpiece and the second workpiece is 0.5-6.5mm, and the zinc-based coating thickness is 70g / ㎡-1200g / ㎡.

Images