Low-carbon high-nickel content 785 MPa grade gas shielded welding wire

Abstract

The invention belongs to the welding material field and mainly relates to low-carbon high nickel content 785 MPa grade gas shielded arc welding soldering wire which is used for high-tensile steel welding. The gas shielded arc welding soldering wire comprises components: 0.02-0.055% of C, less than or equal to 0.30% of Si, 0.6-0.9% of Mn, less than or equal to 0.80% of Cr, 6.8-8.0% of Ni, 0.45-0.60% of Mo, less than or equal to 0.035% of V, less than or equal to 0.075% of AI plus Ti, less than or equal to 0.04% of Re, and the rest of iron. The soldering wire adopts MIG welding, and can reach the following effects: (1) deposited metal and welding microstructure take bainite and martensite mixed microstructure as the main, have low phase transition temperature, can reduce the welding heat stress, thus reducing hydrogen induced cracking sensitivity; (2) deposited metal and welding microstructure contain a small quantity of remaining austenite and adverse transformation austenite; as this kind of austenite has high nickel content, moderate carbon content and strong stability, the austenite can become hydrogen trap to reduce diffusive hydrogen content and also can reduce the capability of diffusive hydrogen which assembles at the lower part of the last welding layer to form the hydrogen induced cracking through interlayer diffusion.

Description

Technical field [0001] The invention belongs to the field of welding materials, and mainly relates to a 785MPa gas shielded welding wire with low carbon and high nickel content, which is used for high-strength steel welding. Background technique [0002] MIG welding is the preferred welding method for welding high-strength steel with a yield strength greater than 700MPa. The welding method is usually equipped with MnNiCrMo welding wire with a medium nickel content (2 to 3%). Its typical representative is the US military standard MIL-E-23765-2E The components specified in MIL120S and MIL130S. Its advantages are: the alloy system has been used and verified in large quantities, the structure is a mid-temperature transformation structure, contains more acicular ferrite, and the weld metal has excellent strength, plasticity and toughness. The disadvantages are: single pass welding and multiple layers The problem of crack resistance of weld metal is more difficult to be solved when wel...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problem of poor crack resistance of high-strength steel weld metal, the gas shielded welding wire was developed by adopting the technical route of low-carbon and high-nickel alloying. The low carbon of ≤0.055% can effectively ensure that the carbon equivalent of the weld metal is in the low range, which is conducive to improving Its crack resistance is also conducive to obtaining low-carbon martensite with relatively good toughness and plasticity. The nickel content of 6.8-8.0% can provide sufficient solid solution strengthening on the one hand, and can reduce the transformation point on the other hand. At the same time, stable Retained austenite and reverse transformed austenite structure, further through the optimization of SiMnCrMo element content, can keep the weld metal structure as a martensitic bainite mixed structure, and obtain further strengthening, and its plasticity and toughness are uniform in excellent condition

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