High-performance composite welding flux and preparation method thereof

Abstract

The invention discloses a high-performance composite welding flux and a preparation method thereof. The high-performance composite welding flux is composed of, by mass, 16%-19% of SiO2, 7%-9% of TiO2, 18%-20% of CaO, 15%-18% of MnO, 22%-25% of CaF2, 0.4%-0.6% of Y and 13%-17% of Al-Mg alloy. The high-performance composite flux is a sintered flux, the viscosity of slag after welding is low, the deslagging performance is excellent, the mechanical property of a weld joint is excellent, and the good mechanical property can still be maintained under the extreme environment.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular, to a high-performance composite welding flux and a preparation method thereof. Background Art

[0002] As one of the core processes in modern industrial manufacturing, the quality of the weld seam in welding technology directly determines the reliability and safety of engineering structures. In the submerged arc welding process, the welding flux, as a key medium for welding metallurgical reactions, undertakes important functions such as protecting the molten pool, stabilizing the arc, and participating in alloying. Among them, the sintered welding flux has the advantages of precise composition control and high-efficiency mechanized production through the granulation molding process, and is widely used in welding scenarios with strict requirements for the mechanical properties and corrosion resistance of weld seams, such as pipelines and ships.

[0003] In recent years, the fluorinated alkali-type sintered welding flux has significantly improved the desulfurization and dephosphorization efficiency during the welding process by optimizing the ratio of fluoride to basic oxides, and at the same time effectively reduces the oxygen content in the weld seam, thereby improving the low-temperature impact toughness of the weld metal. However, the existing technology still faces two major challenges: one is that excessive fluoride is likely to cause welding fume pollution and pose an environmental risk; the other is the insufficient dynamic matching between the flux composition and the molten pool reaction, resulting in the corrosion resistance strength after welding being difficult to meet the requirements of extreme environments such as offshore engineering.

[0004] Therefore, the present invention is specifically proposed to solve the above technical problems. Summary of the Invention

[0005] The first object of the present invention is to provide a high-performance composite welding flux, which has excellent arc stability during the welding process, good slag detachment and weld bead formation after welding, and there are no obvious pores, cracks and other defects on the surface of the weld seam obtained after welding. Moreover, the obtained weld seam has corrosion resistance while maintaining excellent mechanical properties and can meet the requirements of extreme environments.

[0006] The second object of the present invention is to provide a preparation method of a high-performance composite welding flux.

[0007] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted: The present invention first provides a high-performance composite welding flux, and the high-performance composite welding flux is composed of the following components by mass percentage: SiO 2 16% - 19%, TiO 2 7% - 9%, CaO 18% - 20%, MnO 15% - 18%, CaF 2 22% - 25%, Y 0.4% - 0.6% and Al-Mg alloy 13% - 17%.

[0008] Preferably, the slag detachment rate of the weld seam of the high-performance composite welding flux ≥ 94%.

[0009] Preferably, the impact toughness of the weld seam using the high-performance composite flux at -40°C under the simulated extreme seawater environment is ≥98 J; The tensile strength of the weld seam using the high-performance composite flux for 30 days under the simulated extreme seawater environment is ≥645 Mpa; The yield strength of the weld seam using the high-performance composite flux for 30 days under the simulated extreme seawater environment is ≥533 Mpa; The elongation of the weld seam using the high-performance composite flux for 30 days under the simulated extreme seawater environment is ≥29%.

[0010] The present invention further provides a preparation method of the high-performance composite flux, including the following steps: S1. Weigh SiO 2 , TiO 2 , CaO, MnO, CaF 2 , Y, and Al-Mg alloy and put them into a mixer, add sodium silicate and mix and stir at 15 - 20 r / min for 15 - 20 min; S2. Pelletize the wet-mixed materials into balls using a disk granulator, and put the formed balls into a dryer for drying; S3. Pass the dried flux particles through a 10 - 60 mesh sieve to obtain semi-finished flux; S4. Put the semi-finished flux into a muffle furnace for sintering to obtain the finished flux.

[0011] Preferably, in the step S2, the formed balls are dried at 200 - 250°C for 30 - 60 min.

[0012] Preferably, in the step S4, the semi-finished flux is sintered at 700 - 800°C for 2 - 3 h.

[0013] The beneficial effects of the present invention are as follows: 1. The high-performance composite flux provided by the present invention has excellent slag detachment after welding, beautiful weld formation, stable arc during the welding process, and excellent mechanical properties of the weld seam.

[0014] 2. For the high-performance composite flux provided by the present invention, the content of the CaF 2 component is moderate, which can not only reduce the generation of pores in the weld seam, improve the fluidity of the flux, ensure uniform coverage of the welding area, but also reduce the environmental pollution caused by excessive CaF 2 component.

[0015] 3. By adding heavy rare earth yttrium powder and Al-Mg alloy, the high-performance composite flux provided by the present invention is beneficial to improving the strength, corrosion resistance and thermal stability of the weld metal, so that the weld metal still maintains excellent mechanical properties under extreme environments. Description of the Drawings

[0016] Figure 1 This is the flowchart for preparing the welding flux of the present invention; Figure 2 This is the scanning electron micrograph of the microstructure of the weld obtained after welding with the welding flux prepared in Comparative Example 1 of the present invention; Figure 3 This is the scanning electron micrograph of the microstructure of the weld obtained after welding with the welding flux prepared in Example 3 of the present invention. Detailed Embodiments

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0018] Example 1 The high-performance composite welding flux provided in this example is composed of the following components by mass percentage: SiO 2: 16%, TiO 2: 7%, CaO: 20%, MnO: 17%, CaF 2: 23%, Y: 0.4%, Al-Mg alloy: 16.6%.

[0019] The preparation method of the high-performance composite welding flux provided in this example includes the following steps: S1. Weigh SiO 2 , TiO 2 , CaO, MnO, CaF 2 , Y, and Al-Mg alloy according to the mass ratio and put them into a mixer, add sodium silicate and mix and stir at 15 r / min for 20 min; S2. Pelletize the wet-mixed materials into balls, and put the formed balls into a dryer for drying. The drying temperature is 200 °C and the drying time is 60 min; S3. Pass the dried welding flux particles through a 10-60 mesh sieve to obtain semi-finished welding flux; S4. Put the semi-finished welding flux into a muffle furnace for sintering. The sintering temperature is 700 °C and the sintering time is 3 h to obtain the finished welding flux.

[0020] Example 2 The high-performance composite welding flux provided in this example is composed of the following components by mass percentage: SiO 2: 17%, TiO 2: 8%, CaO: 18%, MnO: 15%, CaF 2:25%, Y: 0.5%, Al-Mg alloy: 16.5%.

[0021] The preparation method of the high-performance composite welding flux provided by this embodiment includes the following steps: S1. Weigh SiO 2 , TiO 2 , CaO, MnO, CaF 2 , Y, and Al-Mg alloy and put them into a mixer. Add sodium silicate and mix and stir at 20 r / min for 15 min; S2. Granulate the wet-mixed materials into balls by disk granulation. After granulation, put them into a dryer for drying. The drying temperature is 250 °C and the drying time is 45 min; S3. Pass the dried welding flux particles through a 10-60 mesh sieve to obtain semi-finished welding flux; S4. Put the semi-finished welding flux into a muffle furnace for sintering. The sintering temperature is 750 °C and the sintering time is 2.5 h to obtain the finished welding flux.

[0022] Example 3 The high-performance composite welding flux provided by this embodiment is composed of the following components by mass percentage: SiO 2: 19%, TiO 2: 9%, CaO: 18%, MnO: 15%, CaF 2: 22%, Y: 0.6%, Al-Mg alloy: 16.4%.

[0023] The preparation method of the high-performance composite welding flux provided by this embodiment includes the following steps: S1. Weigh SiO 2 , TiO 2 , CaO, MnO, CaF 2 , Y, and Al-Mg alloy and put them into a mixer. Add sodium silicate and mix and stir at 17 r / min for 15 min; S2. Granulate the wet-mixed materials into balls by disk granulation. After granulation, put them into a dryer for drying. The drying temperature is 300 °C and the drying time is 30 min; S3. Pass the dried welding flux particles through a 10-60 mesh sieve to obtain semi-finished welding flux; S4. Put the semi-finished welding flux into a muffle furnace for sintering. The sintering temperature is 800 °C and the sintering time is 2 h to obtain the finished welding flux.

[0024] Comparative Example 1 The sintered welding flux provided by this comparative example is composed of the following components by mass percentage: SiO 2: 19%, TiO 2:9%, CaO: 18%, MnO: 15%, CaF 2: 22%.

[0025] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 3.

[0026] Comparative Example 2 The sintered flux provided in this comparative example is composed of the following components by mass percentage: SiO 2: 19%, TiO 2: 9%, CaO: 18%, MnO: 15%, CaF 2: 22%, Y: 0.6%.

[0027] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 3.

[0028] Comparative Example 3 The sintered flux provided in this comparative example is composed of the following components by mass percentage: SiO 2: 19%, TiO 2: 9%, CaO: 18%, MnO: 15%, CaF 2: 22%, Al-Mg alloy: 16.4%.

[0029] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 3.

[0030] Experimental Example 1 The slag removal performance of the fluxes prepared in each example and each comparative example was tested respectively, and the results are shown in Table 1.

[0031] Among them, the slag removal performance test was carried out by the falling ball method. A steel ball with a mass of 100 g was dropped freely from a height of 1 m above the steel plate with an initial velocity of 0 to impact the weld seam. The slag shells of the flux dropped each time were collected and measured, and the un-dropped slag shells were cleaned and weighed. Each group was repeated 3 times.

[0032] Table 1 Slag removal rate test of each flux As can be seen from Table 1, in each example, the slag removal efficiency after welding has been greatly improved. In Comparative Example 1, because no yttrium powder and Al-Mg alloy were added, the slag removal efficiency was low. In Comparative Example 2, yttrium powder was added but no Al-Mg alloy was added, and the slag removal performance was slightly worse than that of Comparative Example 3.

[0033] Experimental Example 2 The fluxes described in the examples and comparative examples were dried in an oven at 350 °C for 2 h before welding. Then, the dried sintered flux was used to weld Q390 carbon steel in combination with submerged arc welding wire H08MnA. The mechanical properties of the welds obtained after welding are shown in Table 2 below.

[0034] The -40 °C low-temperature longitudinal impact toughness test was carried out using a pendulum metal impact testing machine, and the tensile strength, yield strength and elongation tests were carried out using a tensile testing machine. Among them, each weld was tested three times.

[0035] Table 2 Weld Mechanical Property Test As can be seen from Table 2, the mechanical properties of each example are good, and there is a significant improvement compared with Comparative Example 1. This is because aluminum-magnesium alloy and yttrium powder were added in Examples 1 to 3. The aluminum-magnesium alloy has a low melting point, and after deoxidation reaction with impurities in the weld, Al 2 O 3 and MgO are obtained. MgO is an excellent slag-making material and has the effect of improving the impact toughness of the weld metal. Al 2 O 3 is a stable amphoteric oxide, which can improve the oxidation resistance of the weld bead surface. Adding aluminum-magnesium alloy not only makes the weld more pure, but also generates an appropriate amount of slag-making agent Al 2 O 3 and MgO. Yttrium is a rare earth element. In addition to improving the thermal crack resistance and corrosion resistance stability of the weld metal, it can also improve the mechanical properties of the weld metal, especially the low-temperature impact toughness.

[0036] Experimental Example 3 The fluxes described in the examples and comparative examples were respectively immersed in the simulated seawater solution after welding. The simulated seawater was prepared based on ASTM D1141−98(2013), and the measured pH value was 8.1; the degradation effect of the mechanical properties of the weld in the seawater corrosion environment was explored.

[0037] Among them, the welds obtained from the examples and comparative examples were respectively immersed in the simulated seawater solution for 7 d, 15 d, and 30 d, and then the -40 °C low-temperature longitudinal impact toughness test, tensile strength, yield strength and elongation tests were carried out again. The mechanical property data obtained are shown in Table 3 below.

[0038] Table 3 Weld Mechanical Property Test after Seawater Immersion As can be seen from Table 3, the experimental examples can still maintain good mechanical properties after the welds after welding are immersed in the seawater solution, while the mechanical properties of the comparative examples are poor and cannot resist seawater erosion. This is because yttrium and aluminum-magnesium alloy were added in the experimental examples. Adding trace rare earth elements to the aluminum-magnesium alloy can improve the structure of the alloy, achieve the effects of refining grains and removing harmful impurities, and can improve the strength of the aluminum-magnesium alloy, improve the processing performance of the aluminum-magnesium alloy, and also improve the toughness and corrosion resistance of the alloy.

[0039] The weld microstructure diagrams obtained after welding the soldering fluxes prepared in Example 3 and Comparative Example 1 are as follows Figure 3 and Figure 2 shown

[0040] From Figure 2 and Figure 3 it can be seen that in the weld microstructure after welding, interlaced acicular ferrite can be found within the grains. With inclusions as the nucleation cores, it can effectively improve the low-temperature impact toughness of the weld

[0041] The above is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention

Claims

1. A high performance composite flux, characterized in that: It is composed of the following components in mass percentage: SiO2 16%~19%, TiO2 7%~9%, CaO 18%~20%, MnO 15%~18%, CaF2 22%~25%, Y 0.4%~0.6% and Al-Mg alloy 13%~17%.

2. The high performance composite flux according to claim 1, characterized in that: The slag removal rate of the high-performance composite flux weld is ≥94%.

3. The high performance composite flux according to claim 1, characterized in that: The impact toughness of the weld using the high-performance composite flux in a simulated seawater extreme environment for 30 days at -40°C is ≥98J; The tensile strength of the weld using the high-performance composite flux in a simulated seawater extreme environment for 30 days is ≥645Mpa; The yield strength of the weld using the high-performance composite flux in a simulated seawater extreme environment for 30 days is ≥533Mpa; The elongation of the weld using the high-performance composite flux in a simulated seawater extreme environment for 30 days is ≥29%.

4. A method for preparing the high-performance composite flux according to claims 1 to 3, characterized in that: The steps include: S1. Weigh SiO2, TiO2, CaO, MnO, CaF2, Y, and Al-Mg alloy according to the mass ratio and put them into a mixer. Add sodium water glass and mix at 15-20r / min for 15-20min. S2, the wet mixed material is granulated into balls by disc, and the balls are put into a dryer for drying; S3, passing the dried flux particles through a 10-60 mesh sieve to obtain a semi-finished flux; S4. Put the semi-finished flux into a muffle furnace for sintering to obtain a finished flux.

5. The method for preparing a high-performance composite flux according to claim 4, characterized in that: In the step S2, the balled material is dried at 200-250° C. for 30-60 minutes.

6. The method for preparing a high-performance composite flux according to claim 4, characterized in that: In the step S4, the semi-finished flux is sintered at 700-800° C. for 2-3 hours.

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