Manufacturing method of x80 pipeline steel straight seam welded pipe

Abstract

The invention belongs to the field of manufacturing of mechanical equipment, and in particular, relates to a manufacturing method of an X80 pipeline steel straight welded pipe. The manufacturing method of the X80 pipeline steel straight welded pipe comprises the process steps of: preparation procedure, edge milling, UOE or JCOE process molding, prewelding, inner welding, outer welding, inspection procedure before diameter expansion, steel pipe diameter expansion, water pressure experiment and product inspection. The manufacturing method adopts a brand new design for a welding groove form, renewedly distributes the welding line energy of inner and outer welding beads, increases the welding line energy of the outer welding beads, and reduces the welding line energy of the inner welding beads. The reduction of the welding line energy of the inner welding beads can prominently reduce the size of grains in a critical coarse grain area of a heat affected zone to facilitate the distribution discretization of chained M-A components, and can reduce the size of the M-A components to obviously promote the toughness of the heat affected zone. In addition, although the filling quantity of the outer welding beads is increased, the welding speed can be guaranteed without reducing the production efficiency through adjusting such process parameters as welding current and voltage.

Description

technical field [0001] The invention belongs to the field of mechanical equipment manufacturing, and in particular relates to a method for manufacturing a straight seam submerged arc welded pipe, which is used for oil and gas transportation and is suitable for the manufacture of Φ1422mm×21.4mm X80 pipeline steel straight seam welded pipe. Background technique [0002] With the implementation of pipeline projects such as the West-to-East Gas Pipeline Project, pipeline steel has developed rapidly in China since 2000. At present, the manufacturing level of domestic pipeline steel has been at the forefront of the world. At this stage, the gas pipelines being laid are mainly made of X80 pipeline steel. The performance indicators of the X80 pipeline steel parent material currently produced can meet the standard requirements, but there are still many problems in the welding process; moreover, in oil and gas pipelines, the weld length accounts for a large proportion, so welding The...

AI Technical Summary

Problems solved by technology

The critical coarse-grained zone can lead to a significant decrease in the impact toughness of the welded heat-affected zone, making the overall performance of the welded joint lower than the requirements of the relevant standards. In actual production, most of the low values ​​in the Charpy impact test are below 50J

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