Large-heat input gas-electric vertical welding gas shielded flux-cored wire based on grain refinement mechanism

Abstract

The invention provides a large-heat input gas-electric vertical welding gas shielded flux-cored wire based on a grain refinement mechanism. The large-heat input gas-electric vertical welding gas shielded flux-cored wire comprises a flux-cored wire outer skin and inner powder, wherein a low-carbon steel cold-rolled steel strip is adopted by the flux-cored wire outer skin, and the flux-cored wire comprises, by mass, less than 0.06% of C, less than 0.3% of Si, less than 0.8% of Mn, less than 0.02% of P, less than 0.01% of S, and the balance Fe and inevitable impurities; the powder comprises, by mass, 1-5% of one or two of titanium dioxide or rutile, 2-6% of quartz sand, 3-8% of feldspar, 1-5% of magnetite, 2-5% of one or more of lithium oxide, sodium oxide or potassium oxide, 10-15% of low-carbon ferromanganese, 3-8% of aluminum powder, 3-8% of ferrotitanium, 2-6% of nickel powder, 2-6% of rare earth silicon, 1-3% of magnesium powder, and the balance reduced iron powder; and the powder accounts for 15-20% of the total mass of the flux-cored wire. The flux-cored wire can be used for 100kj / cm-300kj / cm large-heat input gas-electric vertical welding of a thick steel plate.

Description

technical field [0001] The invention relates to a gas-shielded flux-cored welding wire, in particular to a gas-shielded flux-cored wire for gas-electric vertical welding with large heat input based on a grain refinement mechanism. Background technique [0002] At present, with the development of modern manufacturing industry's demand for various large-scale steel structures, the quality and efficiency of steel structure welding have attracted more and more attention. In order to improve the construction welding efficiency of the steel structure manufacturing site and reduce the construction cost, the large heat input gas-electric vertical welding technology has been more and more applied. Gas electric vertical welding is a special vertical upward welding technology developed on the basis of melting electrode gas shielded welding, generally using CO 2 Gas protection, using water-cooled copper sliders or slides to force the molten metal in the molten pool to form, while preve...

AI Technical Summary

Problems solved by technology

[0004] First, prolonging the high temperature residence time increases the degree of burning of beneficial alloying elements and weakens the alloying effect of the weld;

[0005] Second, the extension of the high temperature residence time increases the tendency of the original columnar grains to grow. This irreversible process cannot be effectively refined in the subsequent cooling process, and the coarsening of the grains is likely to cause various embrittlements of the welded joints;

[0006] Third, after the cooling rate is reduced, high-temperature solid-state phase transformation is prone to occur, and pro-eutectoid massive ferrite or Widmanstatten structure with coarse grains is formed

Due to the high alloy content of the flux-cored wire, the weld metal cold crack sensitivity index P cm The value can reach 0.22. High Cr and Mo content increase the hardening tendency of the weld metal, and various precipitates of alloying elements hinder dislocation movement and also cause a decrease in the elongation of the welded joint.

Chinese patent application number CN201611163806.8 and other patents combine the advantages of good welding process performance of acidic slag system and low hydrogen type slag system, with good process performance and joint mechanical properties, but the applicable welding heat input range is limited

Chinese patent application number CN201510350945.0 discloses a gas-shielded flux-cored wire for gas-electric vertical welding with large heat input, which adopts the joint action of Ti, B and rare earth to strengthen and toughen the mechanism, and adopts a higher carbon content configuration , when the welding heat input is too high, there is a risk of weld embrittlement

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