A high-toughness self-shielded flux-cored wire suitable for welding high-grade steel pipes

Abstract

The invention discloses a high-toughness self-protecting flux-cored wire applicable to welding of a high-grade steel pipeline and belongs to the field of a welding material. The self-protecting flux-cored wire consists of a steel belt and flux core powder, and is characterized in that the welding wire comprises the following chemical deposited metal ingredients in percentage by mass: 0.01wt% to 0.08wt% of C, 0 to 0.5wt% of Si, 0.5wt% to 2.0wt% of Mn, smaller than or equal to 0.02wt% of P, smaller than or equal to 0.01wt% of S, 0.5wt% to 1.5wt% of Al, 3.0wt% to 4.5wt% of Ni, one or several of alloy elements including 0 to 0.08wt% of V, 0 to 0.5wt% of Co, 0 to 0.06wt% of Zr and 0 to 0.02wt% of rare-earth Ce, and the balance of Fe and inevitable impurities. The high-toughness self-protecting flux-cored wire has the advantages that generation of lots of smoke and harmful gases is prevented during a welding process of the flux-cored wire; the content of nitrogen and oxygen in a melting pool is relatively low; the content of free nitrogen in weld metal can be reduced below 150ppm; solidified tissues of a weld joint are thinned lath bainite tissues and particle-like bainite tissues; MA components are thinned and dispersed; the impact toughness of a self-protecting weld joint is effectively improved.

Description

technical field [0001] The invention belongs to the field of welding materials, and in particular relates to a high-toughness self-shielded flux-cored wire suitable for welding high-grade steel pipes, especially suitable for all-position self-shielded welding flux-cored wires for high-grade steel pipes (X80, X90, X100) . Background technique [0002] After nearly 50 years of development since the advent of self-shielded flux-cored wire, it has developed from the initial pursuit of process performance to the current high-quality self-shielded flux-cored wire with high strength, high toughness and capable of all-position welding. As an efficient, convenient and economical new welding material, self-shielded flux cored wire has been widely used in oil and gas pipelines, offshore platforms and other fields, and has broad development prospects. In addition to the characteristics of flux-cored wire, self-shielded flux-cored wire has the following advantages: ① No need to add shie...

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Problems solved by technology

[0003] However, since the self-shielding flux cored wire is a welding material without external gas protection, the content of oxygen and nitrogen in the weld metal is high, which often makes the toughness of the line pipe welded joints often fluctuate greatly

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