Submerged-arc welding flux matched with 850MPa-grade weather-proof high-strength steel

Abstract

The invention belongs to the technical field of welding materials and discloses a submerged-arc welding flux matched with 850MPa-grade weather-proof high-strength steel and a production and use methodthereof. The welding flux is formed by mixing various ore raw materials and a small amount of alloy powder. The welding flux comprises the following main components: 17-33% of fluorite; 0.1-0.5% of lanthanide series rare earth; 16-21% of zircon sand; 2.5-4% of manganese-iron alloy; 20-37% of fused magnesia; 2-9% of natural wollastonite; 12 to 26% of bauxite; and 2-4% of solid water glass. The welding flux comprises a binder. The main components are uniformly mixed according to the proportions; 20-21.5% of the binder is added into the uniformly mixed main components; an obtained mixture is granulated; an obtained substance is subjected to low-temperature baking at 200-230 DEG C, high-temperature sintering at 680-730 DEG C, and screening sequentially, so that a flux product of which the alkalinity ranges from 2.8 to 3.0 and of which the mesh number ranges from 20 to 50 is obtained. When the welding flux and a special welding wire are matched with each other to weld the 850MPa-grade weather-proof high-strength steel, a deposited metal is obtained. The chemical component C of the deposited metal is smaller than or equal to 0.10%; the chemical component Mn of the deposited metal rangesfrom 1.0 to 2.2%; the chemical component Si of the deposited metal is smaller than or equal to 0.60%; the chemical component P of the deposited metal is smaller than or equal to 0.020%; the chemicalcomponent Cr of the deposited metal is smaller than or equal to 0.60%; the chemical component Mo of the deposited metal ranges from 0.20 to 0.60%; the chemical component Ni of the deposited metal ranges from 2.00 to 3.30%; the chemical component Cu of the deposited metal is smaller than or equal to 0.25%; and the balance of the deposited metal is Fe.

Description

technical field [0001] The invention belongs to the technical field of welding consumables, and in particular relates to a submerged arc welding flux for 850MPa grade weather-resistant high-strength steel. Background technique [0002] Welded steel bridges have shown a trend towards large-span and high-grade steel bridges. One of the main objectives of this project is the research and development of yielding Strength 690MPa low yield strength ratio weather-resistant bridge steel plate and its supporting welding consumables (theoretical tensile strength of Q690qENH steel plate is Rm≥810MPa). In actual research and development, considering that the production of the newly developed Q690qENH steel plate is prone to fluctuations in tensile strength due to thickness differences, especially the actual tensile strength of the thin plate may reach 850MPa or even higher. Based on the construction of the bridge, the strength of the deposited metal of the welding material needs to be...

AI Technical Summary

Problems solved by technology

Based on the construction of the bridge, the strength of the deposited metal of the welding material needs to be matched with the actual strength of the Q690qENH steel plate to achieve better comprehensive performance of the welded joint. The tensile strength of the metallized strength is about 810MPa, which does not match the strength of the 850MPa Q690qENH steel plate

[0003] For steel, with the increase of alloy elements in steel, the strength level also increases correspondingly, but the weldability of steel gradually deteriorates, especially for high-strength steel of 800-1000MPa level, a slight increase in strength will have a negative impact on weldability. have a greater impact

[0004] Patent CN201910005188.1 discloses a 800MPa weather-resistant high-strength steel supporting flux for bridges and its preparation method, but due to the large difference in weldability between 850Mpa high-strength steel and 800MPa high-strength steel: (1) The quenching of 850Mpa high-strength steel in the heat-affected zone The hard tendency is more obvious, the sensitivity to cold cracks and hot cracks is greater, and the coarse grain area is brittle; (2) The forming of 850MPa high-strength steel has disadvantages such as high strength, large structural stress, large springback, and low forming accuracy, and the construction area is wide , Poor working conditions and difficult control of process conditions increase the tendency of welding defects; therefore, the flux of 800 high-strength steel cannot be directly applied to 850Mpa high-strength steel

Moreover, due to the large volume of the steel structure used in the bridge, it is difficult to achieve preheating before welding, and there is a certain degree of operational difficulty in hydrogen elimination treatment after welding, and the temperature often cannot reach the expected preheating and postheating temperatures

At present, when most fluxes are used, the base metal needs to be preheated and post-weld dehydrogenation treatment, but if the base metal preheating treatment and post-weld dehydrogenation treatment are insufficient, the weld will have low strength, poor low-temperature toughness, Poor weather resistance, high crack sensitivity and other disadvantages affect the overall quality of the bridge structure

[0005] At present, there is no special submerged arc flux for the 850Mpa Q690qENH steel plate, and the existing submerged arc flux cannot be directly used for welding

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