GMAW-Ar welding method for Q420B steel plate

Abstract

The invention provides a GMAW-Ar welding method for a Q420B steel plate. The GMAW-Ar welding method for the Q420B steel plate comprises the following steps: S1: making asymmetric X-shaped grooves in specimens, S2: grinding the groove surface and the periphery of the grooves within 20 mm with a grinding wheel machine, S3: assembling the ground specimens, S4: position welding the assembled specimens, S5: preheating the specimens by a flame heating method before welding, S6: welding the bottom by adopting the GMAW-Ar method, S7: carrying out welding through the GMAW-Ar method, S8: cleaning root of a bottom welding pass by carbon arc air gouging, S9: controlling the interlayer temperature between 150 and 200 DEG C by the flame heating method, S10: cleaning up slag and spatter during welding, and S11: detecting flaw. The GMAW-Ar welding method for the Q420B steel plate can effectively control the cold crack and the laminar tearing tendency and improve the welding quality.

Description

technical field [0001] The invention relates to a welding method, in particular to a GMAW-Ar welding method for a Q420B steel plate. Background technique [0002] Q420BB is a low-alloy high-strength structural steel. With the development of my country's industry, new high-strength structural steel represented by Q420B is widely used in the production and construction of building steel structures and large-span steel pipe towers for transmission lines. The difficulty of welding in steel structure engineering can be divided into four difficulty levels from A to D according to the carbon equivalent of steel in GB / 50661-2011. Usually, the weldability of steel is judged according to the carbon equivalent of steel. The greater the carbon equivalent of steel, the more The greater the tendency of weld cold cracks, the worse the welding performance, and the welding difficulty is relatively greater. [0003] However, due to the addition of strong carbide-forming elements such as V, T...

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Problems solved by technology

[0003] However, due to the addition of strong carbide-forming elements such as V, Ti, and Nb in Q420B low-alloy high-strength structural steel, it affects the performance of the weld and makes its welding performance not stable enough.

Since the content of each alloy element in the steel has slight changes in each batch, the carbon equivalent of Q420B also has slight changes, the range of which is between 0.45-0.47, and the welding difficulty belongs to C level. From the perspective of welding performance, Q420B It is more difficult to weld; from the analysis of the plate thickness of the components, the greater the plate thickness, the worse the performance of the steel plate in the Z direction, and the greater the welding shrinkage of the thick plate. Therefore, the Q420B steel plate is prone to lamellar tearing tendency during welding. lead to poor welding effect

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