Low-alloy high-strength steel welding method for improving plastic strain capacity

Abstract

The invention relates to a low-alloy high-strength steel welding method capable of improving plastic strain capacity, which comprises the following steps: selecting the same low-alloy high-strength steel plates for combination and butt joint, and the yield strength of the steel plates is less than or equal to 690MPa; a V-shaped groove is adopted, and a backing plate is arranged on the back of the groove; when the wall thickness of the steel plate is less than or equal to 15mm, the angle of the groove surface is 20-45 degrees, the assembling gap is 2-8mm, and the opening width of the assembled groove is 10-35mm; when the wall thickness of the steel plate is larger than 15 mm, the angle of the groove surface is 15-35 degrees, the assembling gap is 4-10 mm, and the opening width of the assembled groove is 15-50 mm; a solid-core welding wire consumable electrode gas shielded welding process is adopted, and protective gas is mixed gas of argon and carbon dioxide; the cosmetic welding material and the steel plate meet a relational expression; according to different wall thicknesses and groove widths, a welding bead arrangement mode and a welding wire swinging mode are selected; the welding current, the welding voltage, the welding speed, the welding wire diameter and the protective gas flow meet certain conditions. The fatigue performance of a welded joint can be improved, and the service life can be prolonged.

Description

technical field [0001] The invention relates to low-alloy high-strength steel welding technology, in particular to a low-alloy high-strength steel welding method for improving plastic strain capacity. Background technique [0002] Low-alloy high-strength steel is widely used in industrial fields such as construction machinery, marine structures, rail vehicles, and heavy energy equipment. It has good strength, toughness and weldability. Welding is the key technology and main process of on-site manufacturing. Due to the non-equilibrium heating and cooling of the welding process itself and the non-equilibrium solid-state phase transition caused by it, the performance of the welded joint is weakened, resulting in various problems in the process of manufacturing and service. Structural failure. Welded structures made of low-alloy high-strength steel are mostly used in alternating variable load occasions in these industrial fields. The bearing capacity of welded joints is much lo...

AI Technical Summary

Problems solved by technology

However, these methods basically belong to post-weld treatment technology, which requires on-line or off-line post-treatment of welded joints, which increases the production cycle and cost

Moreover, if the technical details of the post-weld treatment cannot be effectively controlled, it will lead to a decrease in the fatigue performance of the welded joint. source of fatigue cracks in the process to accelerate structural failure

[0005] Chinese patent 201210133441.X discloses a solid welding wire that improves the fatigue performance of high-strength steel welded joints in construction machinery. The weld metal forms alloy martensite to ensure strength, toughness and wear resistance. By adjusting the alloy composition, the welding residual tensile stress The fatigue strength reduction caused by this method is reduced to a minimum or zero to improve the fatigue strength of welded joints, but this type of welding material is designed for high Cr, Ni and carbon-free alloy components, the cost is very high, and the prospect of batch application is not yet clear

In addition, the increase of the alloy content will lead to poor spreadability of the welding bead on the cover surface, which is not conducive to the uniform and smooth transition of the weld toe, but will cause a decrease in fatigue performance

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