High-strength low-alloy steel submerged-arc welding seam capping bead welding method

Abstract

The invention discloses a high-strength low-alloy steel submerged-arc welding seam capping bead welding method. The high-strength low-alloy steel submerged-arc welding seam capping bead welding methodincludes the following steps that 1, a groove is filled by adopting a conventional submerged arc welding process until the last two layers of weld beads are not filled; 2. 2, when welding of the lastlayer of weld bead is carried out, the edges of the two sides of the last layer of welding bead is controlled to both exceed the edges of the two sides of the original groove by a proper distance; 3,after filling of the last layer of weld bead is finished, a layer of tempering weld bead is additionally welded to the last layer of weld bead; and 4, grinding and removing of the tempering weld beadare carried out to make the welding seam flush with base metal. In the high-strength low-alloy steel submerged-arc welding seam capping bead welding method, the tempering weld bead is additionally arranged on the last layer of capping bead, so that grains in a coarse grain region of a heat affected zone generated by the last layer of the capping bead are refined, the texture performance of the capping bead is optimized, and the problem that conventional submerged-arc welding is adopted, as the coarse grain region of the heat affected zone on the joint surface cannot be subjected to temperingby subsequent weld beads to refine the grains and optimize the texture, the coarse grain region of the heat affected zone on the joint surface has cold cracks and reheat cracks and other defects is solved.

Description

technical field [0001] The invention relates to the technical field of welding technology, in particular to a method for covering weld bead welding of submerged arc welding seams of high-strength low-alloy steel materials. Background technique [0002] High-strength low-alloy steels (such as BHW35, 16MND5, 18MND5, SA-508Gr.3 Cl.2, SA-533B Cl.2, etc.) are widely used in boiler drums, chemical containers, civil nuclear power plant pressure vessels, and many It is used in the form of medium-thick plate or thick forging, and its welding is generally welded by automatic submerged arc welding. [0003] Due to the large thickness of the joints of this material, such materials are generally used for submerged arc welding with larger specifications such as φ4.0 or φ5.0. The welding current is large and the heat input is high. resulting in obvious coarse grains. [0004] The conventional submerged arc welding method of joints does not make special regulations on the cover welding of...

AI Technical Summary

Problems solved by technology

According to this method, the coarse-grained zone in the fusion zone produced by other welds except the last layer of weld can be reheated and tempered during subsequent weld bead welding, and the grains in the coarse-grained zone will be refined to a certain extent, and the microstructure and properties will be improved. It can be optimized to a certain extent, but the coarse-grained region of the fusion line produced by the last weld pass on the cover surface of the weld cannot be tempered by the subsequent weld pass, the coarse grains cannot be refined, and the structure cannot be improved. The toughness is poor, and the defect tendency of cold cracks and reheating cracks is obvious; when the joint base metal itself has poor toughness reserve, and because it is on the joint surface, the stress is the largest, and it is very easy to appear cold cracks and cracks in the weak link of the heat-affected zone. Defects such as reheat cracks

Images