A high heat input gas-electric vertical welding gas-shielded flux-cored wire based on tissue homogenization mechanism

Abstract

A large heat input gas-electric vertical welding gas-shielded flux-cored wire based on a tissue homogenization mechanism, including a flux-cored wire sheath and a powder, wherein the flux-cored wire sheath is made of cold-rolled thin steel strip; 15 to 25%, the mass percentage of the composition is: one or both of titanium dioxide or rutile: 1 to 3%, feldspar: 2 to 6%, water glass: 1 to 4%, lithium oxide: 1 to 4% %, low carbon ferromanganese: 4~10%, ferrosilicon: 4~8%, aluminum powder: 1~5%, molybdenum ferro: 2~5%, nickel powder: 2~6%, rare earth silicon: 4~8% %, boron powder: 0.05-0.1%, and the rest is reduced iron powder. The invention can be applied to gas-electric vertical welding with large heat input of more than 100kJ / cm of medium-thick steel plate, and meets the requirements of high-heat input gas-electric vertical welding of medium-thick steel plates of steel grades of 690MPa and below, and the maximum welding heat input can reach 300kJ / cm.

Description

technical field [0001] The invention relates to a gas-shielded flux-cored welding wire, in particular to a high-heat input gas-electric vertical welding gas-shielded flux-cored wire based on a tissue homogenization mechanism, which can be applied to gas-electric vertical welding with a large heat input above 100kJ / cm. Background technique [0002] Gas electric vertical welding is a special vertical upward welding technology based on gas shielded metal welding, generally using CO 2 Gas protection, using water-cooled copper slider or slide plate and welding groove to form a cavity, molten welding metal fills the cavity and then cools to form. With the continuous development of the demand for various steel structures in the current large-scale manufacturing industry, the requirements for the quality and efficiency of steel structure welding are also getting higher and higher. For medium-thick steel plates of commonly used steel structures, through proper welding groove design ...

AI Technical Summary

Problems solved by technology

[0004] First, the extended high temperature residence time caused by high heat input welding causes a large amount of beneficial alloying elements to be burned, and the alloying effect of the weld is weakened;

[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 weld metal. Various precipitates of alloying elements hinder dislocation movement and also cause the decline of welded joint elongation and low temperature impact toughness. In the occasions requiring high toughness Has a certain technical risk

[0011] Chinese patent application number CN201611163806.8 combines the advantages of good welding process performance of acid slag system and low hydrogen type slag system. It has good process performance and joint mechanical properties, but the applicable welding heat input range is limited.

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