Method for manufacturing high-strength X80 steel spiral welded pipe

Abstract

The invention discloses a method for manufacturing a high-strength (X 80) steel spiral weld pipe. The weld pipe adopts a parent metal of X 80 rolled steel plate, and the chemical compositions of weld pipe are: 0.02 to 0.09 percent of C, 0.10 to 0.42 percent of Si, 1.50 to 1.85 percent of Mn, less than or equal to 0.022 percent of P, less than or equal to 0.005 percent of S, less than or equal to 0.45 percent of Cr, less than or equal to 0.50 percent of Ni, less than or equal to 0.30 percent of Cu, less than or equal to 0.35 percent of Mo, less than or equal to 0.025 percent of Ti, less than or equal to 0.11 percent of Nb, less than or equal to 0.06 percent of V, less than or equal to 0.06 percent of Al, less than or equal to 0.008 percent of N, less than or equal to 0.0005 percent of B, and less than or equal to 0.23 percent of Pcm. The manufacturing procedures includes: decoiling, leveling, edge milling, prebending, molding, internal welding, external welding, pipe end expending, hierarchical ultrasonic examination of parent metal, X-ray examination of welded seam, hydraulic pressure test, ultrasonic examination of welded seam, pipe end chamfering, finished product examination, etc. The (X 80) steel spiral weld pipe( ID: 1219mm, thickness:18.4mm) manufactured by the invention successfully solves the problem of poor stability and unsatisfactory welded seam performance, etc. in the manufacturing process of the high-strength (X 80) steel spiral weld pipe, thereby greatly improving the pass-rate and working efficiency.

Description

technical field [0001] The invention relates to a manufacturing technology of a spiral welded pipe, in particular to a manufacturing technology of a Φ1219×18.4mm high-strength X80 steel spiral welded pipe. Background technique [0002] Spiral welded steel pipe is made by spirally bending steel coils according to a certain radius of curvature and then welding them together along the gap between the steel plates. Spiral welded steel pipe has the advantages of low investment and various production varieties, so it has become the most widely used steel pipe manufacturing method in China. However, due to the limitations of its forming method and the relatively low strength of steel pipes for a long time, there are few productions of high-strength, thick-walled steel pipes. At present, the steel used in the steel pipes produced by spiral welded pipes are all X70 steel grade and below, and the maximum wall thickness is only 17.5mm. With the development o...

AI Technical Summary

Problems solved by technology

The current production method still has many problems in the production of high-strength, thick-walled spiral welded steel pipes. The main manifestations are: as the strength and wall thickness of the steel increase, the steel strip in the former, especially the belt on the delivery side The deformation of the steel edge is insufficient. At the same time, the edge trimming process commonly used at present will also cause the phenomenon of underflaring of the edge of the plate. If it is not corrected in the subsequent process, pouting and tightness in the forming seam will easily occur during the forming and occlusion during production. Defects such as outer looseness and misalignment may even cause fatal defects such as weld micro-cracks; problems such as crescent bends in the coil itself significantly affect the forming stability of the steel pipe, making the circumference and ellipticity of the steel pipe change greatly , can not effectively guarantee the stability of the steel pipe dimensions, which will have a certain impact on the on-site butt joint construction of the steel pipe; in addition, with the increase of the strength and wall thickness of the steel, the welding process becomes more difficult, and how to control the structure and performance of the weld A key issue that needs to be addressed