Low-carbon CO2 gas protection welding wire suitable for ultra-low heat input automatic welding and manufacturing method thereof

Abstract

The invention discloses a low-carbon CO2 gas protection welding wire suitable for ultra-low heat input automatic welding. The low-carbon CO2 gas protection welding wire suitable for ultra-low heat input automatic welding is prepared from the following chemical elements comprising, by mass, 0.02%-0.06% of C, 0.6%-1.3% of Si, 0.7%-1.5% of Mn, 0.2%-0.6% of Ti, 1.0%-1.8% of Ni, 0.1%-0.6% of Cu and thebalance of Fe and other inevitable impurity elements. In addition, the invention further discloses a manufacturing method of the low-carbon CO2 gas protection welding wire. The manufacturing method of the low-carbon CO2 gas protection welding wire comprises the steps that raw materials are smelted in a vacuum electric furnace; and a solidified steel ingot is rolled, drawn and wound to obtain thelow-carbon CO2 gas protection welding wire. The design of the relatively low carbon content is adopted in the low-carbon CO2 gas protection welding wire, hardening and embrittlement of welding lines due to rapid cooling of ultra-low heat input welding are reduced, and the metal toughness of the welding lines is significantly improved without significantly increasing the metal strength of the welding lines.

Description

technical field [0001] The invention relates to a welding wire and a manufacturing method thereof, in particular to a gas shielded welding wire and a manufacturing method thereof. Background technique [0002] MMA automatic welding has the advantages of high welding efficiency, good welding quality and convenient operation. It is a welding method commonly used in various industrial fields. Inert gas (such as Ar and He), active gas (such as CO 2 ) or mixed gas (Ar+O 2 , Ar+CO 2 or multiple gas mixtures). Among them, CO 2 Gas shielded welding has the advantages of fast welding speed, large penetration depth and low cost, and is widely used in the industry. [0003] Generally, the heat input range of solid wire melting electrode gas shielded automatic welding is 0.5~1.5kJ / mm, and the ultra-low heat input of 0.25kJ / mm belongs to the extremely harsh welding process conditions. Accelerated metal cooling and severe non-equilibrium solid-state phase transformation will have an...

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Problems solved by technology

[0006] like figure 1 As shown, for API 5LX70M pipeline steel pipes, low-alloy steel commonly used AWS A 5.18ER70S-G gas-shielded solid wire is used for automatic welding with ultra-low heat input of 0.25kJ / mm (shielding gas is 80%Ar+20%CO 2 ), due to the rapid cooling after welding, unevenly distributed strip martensite and a large number of clustered M-A components appear in the weld metal, which leads to a serious decline in its toughness, and the single value of impact energy at -10°C is even lower than 35J, the CTOD fracture toughness value is generally lower than 0.1mm, and some are lower than 0.05mm

[0007] In addition, 80%Ar+20%CO 2 The mixed gas has the characteristics of argon arc. Although the welding process is stable and the spatter is small, due to the characteristics of the argon arc plasma energy distribution center is high and the periphery is low, the fusion ability of the edge of the groove is poor during rapid welding under the requirement of ultra-low heat input. The probability of non-fusion defects is high, and the welding process adjustment window is very narrow

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