A flux-cored welding wire for 620mpa low-temperature steel and its welding method

Abstract

The invention provides a flux-cored wire for 620 MPa-level low-temperature steel. The flux-cored wire for 620 MPa-level low-temperature steel comprises carbon steel skin and a flux core arranged in the carbon steel skin. The flux core comprises the following raw material components, by mass percent, 36%-42% of rutile, 2%-5% of ferromolybdenum, 2%-4% of zircon sand, 15%-20% of electrolytic manganese, 5%-6% of calcium fluoride, 1.5%-3% of an aluminum magnesium alloy, 10%-12% of silicon iron, 3%-5% of ferrotitanium, 1.5%-3% of potassium fluoborate, 9%-10% of nickel powder and the balance ferrous powder and unavoidable impurities. The flux-cored wire for the 620 MPa-level low-temperature steel utilizes CO2 protective gas for welding and has excellent welding process performance and comprehensive performance of deposited metal and a welded joint. The yield strength is larger than or equal to 540 MPa, the extension strength is larger than or equal to 620 MPa, the elongation is larger than or equal to 20%, and under the condition of -60 DEG C, Akv is larger than or equal to 54 J.

Description

technical field [0001] The invention belongs to the technical field of welding material manufacturing, and in particular relates to a flux-cored welding wire for 620MPa low-temperature steel. Background technique [0002] Because of its good all-position welding process performance and high welding efficiency, gas-shielded flux cored wire has been used more and more in various industries of the national economy, especially in shipbuilding, ocean engineering and other industries. Low-temperature high-strength high-toughness welding materials are widely used in the construction of offshore oil drilling platforms, especially flux-cored wires with good low-temperature impact toughness. However, the existing flux-cored welding wire can usually only ensure that the impact energy absorbed at -40°C is greater than 47J, and its low-temperature impact toughness is not ideal. [0003] In steelmaking or welding material deposition metal strengthening theory, many elements can be select...

AI Technical Summary

Problems solved by technology

In the 620MPa class flux-cored wire, if C is used as the main strengthening element, the low-temperature impact toughness at -40°C can be guaranteed, but it is difficult to guarantee the low-temperature toughness at -60°C, and too much C will significantly increase the low-temperature cracking of the weld. Risk; if strengthened with Si, Cr, etc., as its content increases, it is easy to form a coarse ferrite structure in the deposited metal, and its ductile-brittle transition temperature will also increase, and the low-temperature impact toughness is poor, which cannot be solved- Low-temperature toughness problem at 60°C; Nb and V, as trace strengthening elements, are more widely used in the field of steelmaking, and it is difficult to stabilize and homogenize them in flux-cored wires, so the stability of the strengthening effect is poor

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