A 550mpa-grade low-temperature steel supporting flux-cored welding wire

Abstract

The invention belongs to the technical field of welding materials, and particularly relates to a flux-cored wire matched with 550 MPa-grade low-temperature steel. The flux-cored wire is prepared by coating flux core powder with a low-carbon cold-rolled steel strip; and the flux core powder accounts for 18%-35% of the total mass of the wire. A flux core is prepared from components including, by mass, 1.0%-2.0% of Ni-Cr-B-Si-series self-fluxing alloy powder FZNi-45, 1.2%-1.8% of micro-carbon ferromanganese FeMn84C0.05, 3.0%-5.0% of ferrotitanium FeTi80-A, 2.5%-4.5% of rare-earth ferrosilicomagnesium REMgSiFe-07CeC, 2.0%-3.0% of an aluminum intermediate alloy AlSi50, 2.0%-3.5% of nano Mo powder, 3.0%-4.5% of NaF and the balance reduced iron powder FHT100*25.

Description

technical field [0001] The invention relates to the field of welding materials, in particular to a flux-cored welding wire for 550MPa low-temperature steel. [0002] technical background [0003] Flux-cored welding wire can easily design various welding materials for different purposes by adjusting the alloy composition and proportion of the powder. The flux-cored welding wire should match the base metal, and its chemical composition, strength, toughness, etc. The impact is very significant, it has good process performance and high welding efficiency. [0004] Shipbuilding, ocean engineering, oil drilling platforms, production equipment in cold regions, oil pipelines and other steel structures are often made of low-temperature steel with a yield strength of 550MPa in order to prevent brittle damage at low temperatures. Welding low-temperature steel with a yield strength of 550MPa Flux cored wire must also match. At present, the difficulty in the welding technology of low-te...

AI Technical Summary

Problems solved by technology

At present, the difficulty of welding technology for low-temperature steel with a yield strength of 550MPa is that the mechanical properties after welding are not easy to meet the requirements, especially the low-temperature impact toughness is difficult to meet the use requirements

[0005] Chinese patent CN104400250B discloses a low-temperature steel flux-cored welding wire, but it meets the requirements of steel with a yield strength of 460MPa, and aluminum oxide is added as a slagging agent in its composition. During the welding process, under the heat input of the arc, and All the alumina cannot be melted and decomposed, nor will all slag be formed. Part of the alumina will remain in the deposited metal as a hard phase inclusion, which will inevitably lead to a decrease in low-temperature impact toughness.

Moreover, the 15%~25% low-carbon ferromanganese contained in the drug core is also likely to cause excessive Mn elements to form MnS inclusions, which reduces the low-temperature impact toughness.

[0006] Chinese patent CN103692110A discloses a gas-shielded flux-cored welding wire for marine engineering. The yield strength of the deposited metal has reached 375MPa, which belongs to low-temperature steel with general strength and higher strength, and cannot meet the welding requirements of 550MPa-grade low-temperature steel. Require

However, 5% to 6% of medium-carbon ferromanganese and 14% to 18% of silicon-manganese alloy are added to the drug core formula, which will cause the content of Mn and C that are finally dissolved into the deposited metal to be too high, and excessive Mn MnS inclusions will be formed, and excessive C will also form carbide inclusions, greatly reducing the impact toughness of the deposited metal

[0008] Chinese patent CN104708227B discloses a self-shielding flux-cored welding wire for 1Ni9 low-temperature steel and its preparation method. The content of Mn in the flux core is relatively high, plus the Mn in the outer steel strip, and finally enters the Mn element in the deposited metal If the content is too high, it will produce large-sized and uneven MnS inclusions, which will greatly reduce the low-temperature impact toughness of the deposited metal. In addition, its preparation process is complicated. Crushing and sieving increase the difficulty of manufacturing

If C is used as the main strengthening element, its content should not be too high, otherwise the risk of low-temperature cracking of the weld will be significantly increased with the increase of C content, and the strength cannot be guaranteed if the C content is too low; As its content increases, it is easy to form a coarse ferrite structure in the deposited metal, reducing its low-temperature impact toughness; Nb and V, as trace strengthening elements, are difficult to stabilize and homogenize in the deposited metal, so the strengthening effect Poor stability

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